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The effect of changes in certain determinants of ground upon the perception of Beta motion

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Title:
The effect of changes in certain determinants of ground upon the perception of Beta motion
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Hart, Herbert Carlton, 1926-
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English
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v, 48 leaves : ill. ; 28 cm.

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Subjects / Keywords:
Anticipation ( jstor )
Bees ( jstor )
Eyes ( jstor )
Gestalt theory ( jstor )
Graduates ( jstor )
Murals ( jstor )
Optics ( jstor )
Perception ( jstor )
Stripes ( jstor )
Visual perception ( jstor )
Dissertations, Academic -- Psychology -- UF ( lcsh )
Motion ( lcsh )
Movement, Psychology ( lcsh )
Perception ( lcsh )
Psychology thesis Ph. D ( lcsh )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

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Thesis:
Thesis--University of Florida.
Bibliography:
Bibliography: leaves 46-48.
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Also available online.
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Manuscript copy.
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Vita.
Statement of Responsibility:
by Herbert Carlton Hart.

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University of Florida
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THE EFFECT OF CHANGES IN CERTAIN

DETERMINANTS OF GROUND UPON THE

PERCEPTION OF BETA MOTION










By
HERBERT CARLTON HART


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY










UNIVERSITY OF FLORIDA
January, 1959
















ACKJDILZ~DGWnT3


The writer viLhea to expnss his aiacerest appreciatio to the

Chaiman of the Supervisory CoaMtes, Dr. 1. lone. Hse an

ufailiang source of Liepiration and a critical perso Le the formative

tape, and pave wtintLeLy of bhie tiLm. knovwled, and petieae La

guidiag the course of tbhi study.

Hauy thaaks are due the -here of the Supervisory Comittae,

Dre. A. IBarrett, J. C. Dixo, V. W. hruman, S. D. liackley, and

*. s. Webb.

Thaake arn &len due the any per.o.a wh, served ao subjects for

this experimat.



















TAKI or oo3ni


ACUIMJ- aIS . .


L1I W TABSL . .


Lii 01 3LLBTIUALO .O


Chapter

I. 1313 OICTIM


U. AmIATUB AM


UIII. SMLTS .


V. DISCUSIOU AN


V. sMmur. .


A1onz . . ..


*u33u~cg .. ...


Page
htp




iv



V


pacou* *9**




I CONKLUSXO-
cOOsmu


@5*o* S.


* 9e@5S



* S S S


itl
















LIST OF TAfl S


table pRo


l, Measurea of bets MoNtio Accordina to Ground
Propertle . . . * # * 25


l. Cousaiteacy of Grotd Iffects fr Lowr sad
OUpper Plb-rate Thr lelda, OptlIs Rate.
and RaMP of lot Noattios . . . .* 27


3. Aslysia of Variance for Variables Modifying
Lower Flah-rate Thrmwholdt Grounds x
Order of rsentatcot Z epLicaciocs . ,. 30


4. Alysis of Variace for Varlable s ModtEyia
OpCtlml FlMh-rate: Grounds X Order of
Presemtatto X Iplicatios *..... . . 32


5. Aalysis of Varance for Variables Nodifyilg
Upper Flasb-rato Throsbold: Grounds X
Order of Praoetatloa X IeplLicatlous . .. 33


6. AnasLysis t Varianc for Variable Modifyiag
Imp of Motion: Grounds I Order of
Preaemeaio X Itaplicatmo . * * . 34


7. Significance of the Differencas Betwee the
Mans of the Maosures of Bt Motion . .. 36

















LiST OF ILLUSTUA!INSS


FLVur


1. Block DLiarpmof th LLght Pfual .




2. Block DLaram of tW 5xpristm L Mm . . .
















CHAPIn I


IrIMODUCTIOI


The purpoee of this Study IS to investitate thb effects of

certati ehcaeatertics of* fixed oSuads upon the p ieptioi f lita-

type nutio. Ia perceptiom, fs re-rcouad ra Latt"Ohips have bee

aoii mad often reported beiever, thee Uot oft. Levgl. states, um

IIvi. prIceptioe (11, 29). Rely have they bet coerned with

liunre-xouI effects La a dyamic field s reprNesented by the phi-

pheeas (6). There tun beew Is specific lavetati.soei of fLued

vrteLs Pou4d effects o- the peroeptiLe of apparIt =iotie of the

eta-type.

T. neu mtion. Ia relatively iple perceptiom uhih is far-

reaching In its theoretical importanuce. If 0a 0 Is premeted with tw

flashig lights, the flash relNatioshLp betig uch that as oee light,

"A, OMea off, a iacoed liLht, "B", go"e os, the perception -y be that

of a mingle iht which wav froo the first position to chat of the

second (36). If the relacioship IS oetLattIMuos, i*.e., AM A .

As* the perception way be that of a mingle light which mve backwrd

sad arsurd between the tw positions. It my appear to mve Is a two-

41iumuloeml plans, or to & thes-diaimaLosal path. This to the StIa

s (33).

Then a e a nuaber of variables iuvlved as earlier eaxperinats

have shown (4, r1, 24). The fl ash rat la term of complete cyles
r.











per second (A o@, 1 off; A 0f|, am),p the duration of tiM pause, if any,

between A and iteasiaty of the stImluas lights duratioM of the
flasbh, mat of dark adaptatiLom prior to the prestation of the

l0hts. distance betweas the 14k.. Instructions to the 3. lmnth of

thO preeeatatioM, presence of fimar included as tihe fe of the

stimlus lights, and the btkacmd have all bees shoun to be impotraat

variable (1, 2, 16, 34. 37).

The relationship of pause tim betum the light, intemity, maad
spatial sMparatie were further lnvestiBted by torts (15). The foeal

etatmeat is &nI a- Kort's Low. although om of his findings have

recently bee questioned (6). Lorte founa that a short tim inaterval

bteam the two ezxposures, a los distaac bot a the timulus lights,

and a I latensity of stmulus lights made perception of the pihmo-mu

difficult. o ow of those conditions acts i iLtolf; rather, then it

asm important iteraction betwe the variables. Corbin (4) showed in

his experimts that a long distance betMeem the lights ca be bridged

by a long peae time.

There abm bean a mbar of theories atteptian to eplaia

apparent motion. Among the earliest of these ms the ey-movemmt

theory Which stated that the movemat of the eye and their musculature

aeceounted f the perception of the motion. Iwomver. Guilford and

NelsoMn (12) showed that there me -s ialuficant correlationa betwm

tha nport of apparsent motion and the photographic record of eyt mom-

mets durian the report. Wendt (35) shoed that during the perception

of apparent motion., the eyes vwr eagaged la fixating objects just as in

tbhe perception of real movmt.











Imer (7) proposed la 1875 retial mural theory to account
for both real ad apparenat motio. It LnvoLvd the lanteractloa betwe

elements la the rtiLe whn the eliemets 1 uCeesilvely stimuiLaed.

This lateractioe n md sv to mot tate o cot minus prmcpt the *tim-

latiom of1 the serie of dcLfrte pointsl tI re tiame. Nommvr, fth

fiadLas that apparent motion toek plae mum oe stimlus wus prosemud

to m e y ad another stimale to the other eye effectively vitiated

this theory, e then e would aot possibly be a7y timl murl Luater-

actio uwader these cmditioms (S. 31). Werthelmr (36) proposed the

mat step La umodlfilatiou of Bmar's theory. Me planed the mer smey

Lateractioa cntrally, Ia the cerebm l corts, rather then peripherally.

la the retimea.

There have beem a maser of experiments performed min only oa

eye. using both eyes tolgther, and vuia both eyes separately (6, 31).
The" a&lad "t ubetatlcUtiq or xfutiag the mMml Interactla theories.

If both stimulis Litht an presented blaoularly, theIa Lateractioa of

tle geMerated mMnIral ilds could take place at ay poal a low the

visual cortieopetal patimay: the retiLm, the optic shasm, the

latecal Placulate muclei, the optic adiatino, r tI d triate cetem

(Inrmm 's area 17). or ~ ina the monm rwto abortical struetu s

(23., 32). 8 larly, the presenace of the stimulus ligts a em eoy
would rule cut e-half of the peripheraml mi system, but wmuld mon

rult out any of the more central structures because of the hemidesus"

"atae of the optic tract at the level o the optic ehih-m. But by
prsnt Lag ome lit to Osi eye sad mother Iiht to the other ey,

oy17 the central atructurm could be iWmolvod in the Mavn lateactio (37).












Gw lli (8) investicated the affects of heteroaymsu and

boamymous stiaulaton of the etrate eartex isa a attempt to awer

thisU problem of interaction. By hateqrommws stimltIoa he mast

presatiag the st*mlus lights 1 sueb a mamer as Co stlimlate the

striate corta In both bhmispheros. Hoemayu *tisilatim occurred

aim timalatloa took place in oaly am hemisphereo. He ued a spit-

fiald technic by m Mas of baif-Uvered mirrors. presated dlfferest

stimulL to each eye. Undsaryia this techic ts the esumpie n of

spatiaL projection of real setimulastion thr uch the optic cklasm, the

lateral atLculats bodies, the optic radlUtioue, ad the striate corte.,

vwith the preservation pattearnilag La all thoam stnotureas (23). Umdr

those oadtioans, be fouad tkht his sw the Largest mouna of

appaxmat sntiou under th koaaymous coudltlon. N asceribed Wis

fimdlfa to the Ianteractiout of equal fields taking place ia the ortez,

nd not in the subcortial structures of visual corticoptal path.-

wua. However, &s findlags won queioned hy Smith (31).

SaiLth (JR) presented his a with tw lights whieh wen monted

8 a beadband. The lights wo adjusted ina suek a r that tO

iLmps fomad by the lights vt on the oxtrem easel borders of the

rtiaLase. OnaLy M Lighit eouid be ses by either y7e. Tils mad of

proesetatioa resulted A the stimiaLation of the extreme borders f the

striate corte, bordring onm the alcarL=m flssure. This stimlatioa

tha pSv the mzimm possible separatioa o5 the *eso of stimlatile

of the cerebral cortx. Nievrtheless, be obtained from his sed

perception of appamnt mutim on e interpreted his findaigs liag

out nural fIljaid interactions on both the periphelnL sad central levels.











Because of the peculiar spatial projection La the optic chiasm, be

felt that the requtred intsrctioa could aot hav taken pLace at that

lol. Nromover, be iaterpreted hib fiadimp as cotadLctiaS O

usual Gestalt theory of apparent ntieoa. The later study by Corbia

(4) my provide a better frame of rfremnce for the interpretatioa of

these findip them that used by Smith himself.

Corbin (4) presented his Os with the stimulus lights amuapd

as 'roato-lmmllel time at various distances, and than praise d tibm

wUbh *Sallar lines slated at 60 froxm tb vrtical. By so sLaatiag

the UIs., teM actual retiaal separation of the stimulus lig ts Laiolvd

oly half the distance start in the scoad as La the first prmsatatios.

l obtaineMd the ams tim threshold with both types of preseuttioL .

Thmse throebald should has dropped markedly in the second presea-

tatios because of teb lessened spatial separation, if Kort' Law hold.

s interprets hbls fiadlais s being quite difficult to reconcile with

Werthelmer's (3) theory of isouqrphLa which sem to dmand as actual

pkyical separatioa of the area of stimulation iLa t cortex that

rBpeMlal thb analog of the physical separation of tbh stJAll La


Wht does sm important in th interpretatioa of these fiUdin

i that it is mot the physical separation of the areas of tmilatioa but

rather heM parcaptual separation which governs the limma obtained.

This reinterpretation of the fiadiang would briag th. into consomme

with the Gstalt tbaory. Illis (6) considers the pbahnomeon a *fuctie.

of the stire field as a4 integrated Gestalt. It is aot the product of

say me variable i _cuo. Horeover, he would apply this theory











equally to the neural fields of the central nervous system wll ae

the perceptual field. The satinre sale, thm, from the extermal

tUmaulus field those the recepMton, the orticopetal machiLniame, and

the cortenx itself, all enter iLato the final perception: those topther

constitute the fuactioaal wole.

Ts effect of the pound upoa the peroeptiua of f4pm. con-

talaMd wiLthi that found has had a lona history Is psychology, but ba

bee uplored ret exteusively by the Gestalt writers (6). early work

Included that of hiba (28), Gocttlehldt (10, U11). ad Koffia (16, 17).

I generaMl, Rubin woaksd upon the effects is prceptioa of the n-

versibLe iure-grouad Ulusioms. Gottschaldt did miet of his wek

with coanscelmnt of fip tn ground. Those effects wnre all It stati

fields b-w r. Kofka dealt to with the effect of groud is

dynamic fields, as is the pereptioa of apparent meotlon. We will

detail tw approaches hes: that of Duacksr (5) and one of Roffka's
(16) which deal with the dymmic field percept.

Duackar's work dealt with Induced viation the perception of

motion produced Is on. figure by the votioa of another to the field,
and the itiLo prodced is the fpas by the Uou of theI field slinet

which it we semm. In his experiment, Ih emosed sucoessiwely by MameM
of a tacbhtoocops tw rectanles with dot placed upon theam. Tbhe dots

alao uws superiposed t successive presmLations, first in ose ad

themn i a second reeta m I another series of xer nts,

neither the daot nor the rectangles wre superiposd. His f dimp

iLndicated that the fixated figure us the oa e museeptibls to the jauctumoe

of moti.e. Te eaclosed, rather than the aenclosag fif4upre, showed the











greater tendency toward induced motion. It seem reasonable to

interpret his findings as dealing with fiure-ground relationships.

The fixated figure can be considered to be is sharp focus. the non-

fixated figure less so. The one is s en so figure, while the other

tmds to become ground. His findings tihmn indicate hat tiM gtound is

stable, but that the figure is susceptible to the induction of mtioam.

The ground my be considered to form an anchor for the figure: the

figure tos seM to mv against a ground. If the fixated figun is the

enclosing figure, timhen notion is less likely to be Induced. This soom

to indicate that the enclosing figure, altbough fixated, is yet sem as

rouad, ead mot es figure. Bowver, this laterprettio seme the mot

logical onMe in toem of the GestaLt priaciLple of jflsm. Barta a

(13), while he discussed the experlat, does not answer this laterpre-

tatioa, ner does Duacker.

The experiment .moffM (16) performned se Sn refutation of Liake's

(20, 21) earlier otrk. Links'* wore presented with a peuiaphere

(a semitircla with a depressed cmter, the arm pointing up) an which

wa drw a dot. In a succaesioa of presentatios. tbe dot -me placed

to a sert"e of interoodiate positious around the perLspbate. The

perception wa that of a dot tolling around L a a semicircle ag eiot a

find groad. Linsw int rpreted his findings a being t o interpretation

of the percept by the R based upon hbs past experiese.a, e.g., s*uch as

sMing a ball roll around the inside of a bowl. Apparent motiom.

for Links. uws aot a given fact, but was ifaerred from past experience.

Koff&a (16), in a nst reersal of the experimut, refuted

Links's interpretation but confirmed his finding. Koffka presented











his f witVh a sitomilar deiga, but with the apex of the portsphro

pointing upurnd th am dGUmmrd. The perception reported by his

t we Mactly the am an those reported by Ldmhoe but. of course,

past perLance could not now be considered a basis Cor the percept.

Res", Koffka considered apparent motioa & given, not a learned, fact.
Koffs mat further, howevr. Re preated his with tihe dote in

eectly the som position a before, but without the peripbere. Thls

tme the percept se of a series of dots Jumpiag about teboy no longer

rolled smoothly fnm one position to the nsxt. He interpreted his

findings mania perception Is a fuaction of the Sn field, eand

not of ae part of the field without consideratio of the reminder.

Tbhse experLmets ahow without question that theN an definite

effects upoa the pecption of apparent motloa of tha changes in the

ground against wbich thM figure to seen. This hans, of course, beb

hknm a long tim in the otdto uf perception of statc fields. brly

investigation noted that soe figure properties to farm perception of

apparently mvitn objects wvrt influential i perception. Reicheaberg'

study (27) indicates that in the duration of perceived motion significant

difreaces between ll cobinationM of figiire patterns wore not obo

tained. Neitbor in toem of mosa timL for perceived notios nor in

total tiUse of perceived motto. of two lighted figures t otioa mws form

significant variable. In analysis of man time for perception of

.e lbtoed figure i motimo, e.g, optiml emovemmt, tom ms spiifi.

cant in the Y tet. An F test for analysis of variance of total tie

of perceived motion mw not sigaificant. Thus, fiure Lo important it

som mweuremets of apparent motion hut soet in all.











If the figures an differwat in fore or In color, thiW differ-

ea May becaa as important variable la the perception of apparent

motion. orlausky (25) explored thbase variables. e found that if

the stinulus lights an show ia the fogb of two arnwm poiLting in tahe

see direction, nation o easily eam by met As; it is quite cm-

polling. sad ito vry maLlitic. lot if me arxo points to the right

ad the other to the left, it becomes mch unre difficult to perceived

apparent otiLo, ad it is easily lost. Mor tiw nmt be allowed

between flashes (iL., by increasLno the pause tim or by decreasing

the floah rate) if appaent motion to to be seen. Ives so, # con-

siderable uber of a caunot obtain Seod motion under thes coaditias.

Ill, s (6) epLais thi pb o enom m under the hbeadig of I iign and

of commn destiny. oichbeberg (261, 27) carried out as additional

study La this arm. lts findings in general confirmed teose of

Orlansky although he used wry different stimius figures.

ThIM phsMenoe of apparent notion o ast limited entirely to

the use of alternate lighted reas, although this mnde of presentatio

huas been the -at common t heU past (33). Dwos (3) fouad that a

similar phoomms s obtaineod in the perception of rel motion under

cartris oaditions. broin used a cotiLeoua strip of paper to whichL

black reactagles had ben applied, *ad wvariad the speed of rectangles

mving past a slot, A muak coacealed the reniador of the strip.

The o2 observed the wavemnt. Woa tbhe paper me an ig at a high rat

of speed past the slot, the rectangles mre perceived as a contiauoue

bad of grey. At low speeds, the rectagles wave reported as mving











to tlb direction of their real motio. Al certain iatowemdiate speeds,

the it reported the rectangles movin Lu a direction oegsitf to tlw

direction t their objective mmomt. srm iLaterpftd hIU fidin"p

correctly as a trum aoXvle of apprent motion.

The purpose of the present study is to investigate thel effects

of cetala doterminams of pond upoe the percmpptio of beta uiom.

It bae been obho In a mber of esperilmna that grouad be* ea

important effect sm the percept. There are a number of determinants

of ground and figur relatloemhips detailed by tbs Gestalt writer.

Amons the principles determiing the peroept of figure an tbose of

clearness: the figure is more sharply defined thabs io the round.

The ounad is the to" distinct of the tw, sad toeds to be Iwpred in

reports of the percept. The figure to *a Interesting or lively then

theb ground, sad ea to stand out from the around; h ground seam

to continue behind and to be hidden by tbe figure. These principle

are rouped under the genel leading of 2,MB: the smaMingfulese

of tlb parts of the percept (6, 16).

A ascoand principle to that of coams destiny: the figures ad

the pound sem to @hare an *nd comam to both. Tbhio, If vertically

barred ground is presented apnlt which eta s tieo i to be seem,

thee vertical ber caa be thought to bar. a comwa deatimy with the

prc"pt of apparent wotio (6, 16). Under tl principle of "M M a.

mehk a ground should farm & barrier to lb coatinuerd perception of

appnat motion because it force theb apparently vig stimulus lihbts

to cross successively a series of dark and light stripes. Conversely,

a ground which contains strips of light sad dark armnd hborimtally












so that the stripes lie parallel to tbhe anticipated path of apparent

motioe abould facilitate the percept by brnina pethiwys. A similar

percept seem to have occurred in KItoffaae (16) experictnt.

A third principle with which this experimst deals t he

Gestalt principle of iaoiorphbiam the represeetatLoea A mural olemats

of the memory stimlua with preservation of the Geatalt of that timaulus

felid (6, 16). Thus, trauslating the previously presented umodel ato

iLomrpbic term, one would expect that the vertically barred rouad

would stimulate *electively mural elemats, aud that there would be

preservautio of its for lu the patternaing of tbhe atimlatioa. For

eu.mple, such a ground as the vertically barred oa discussed previously,

would set up alternating bends of oecitatios and quieceace in the

striate cortax Lu a exact laog of the original stimulus. Such

conteinauLng stimulus as iso presented by Beta notion would produce an

interacttting moeural field u*h that a continuous band f excLtatiLo

would cross *ad recross the cerebral cortex to exact mural repmsen-

tation of*I the percept of the notion as reported by theb 0.

If the interaction of eural fields st up by the stimulus lights

is neceaary for the percept of apparent otiaon to take place as to

demaded by the Gestalt theory, than it seem likely under the primeiples

Just outlined that certain types of cortical field should act to in-

hibit or to facilitate the perception of apparent motion. In liine

with a Gestalt theory of apparent motion. bade of qhuiuse& f r# o*

citation should be set up in the cortex (strictly speaking, In the

Meuroa making up the cortex) by tbhat round corresponding to tbe











arnrinmt presented by that grtod In visual space, sad these hypo-

thatical band should have am iLerutat effect 0o the perception of

apparent notion (2, 23).

A positLon for the doriLwtou of thNee hypothasese a boom

eatablishbed. The next se top to desip an e xperimat to teat them.

fint, Ut my be anticipated that the nom-figured, i.., plain, ground

will provide the least itearference with apparent motion. It Wil do

this because, uider the principle of ismorphiom, it will consist only

of uniforly excited oaronme. Scause it pose so barrier to the

perceptCioea of apparenat uotio, it is anticipated that it will provide

tbhe larpt flash-ate romi of apparent nation. If the upper flash-

rate threshold or apparent motion t measured, it should follow that

this value Ib increased: the I is able to perceive apparent motion at

a higher flashb-rete before it breaks dowam. It should also follow that

the 9 could perceive apparent notion at lowar flash-rate: the lower

flash rate lilm should be decreased. The net result should be ao

iLncrose i& the reap of flaab-rate. within which apparent motioa my

be perceived.

Secoedly, if a vertically bared ovmnd against whieh apparent

motLio to to be seen to used, it ito anticipated that such a p und

should for a barrier to the perception of apparent anlion. IS tahe

cortx, under the principle of isourphbism, it tois expected that alter-

mattg hands of excitatioa and quiesace correspoadian to the altermatLmg

bands of dark and light oan the ground would be aset up. Since a hori-

Mitally moving iht is produced In tho apparent motion apparatus.

thti mao that the hbaond of excitation sot up by such a percept In











aim qlna mural iold is flbored to croes the altermatiq badm of

Saleeatl asd quiescemne a the ortew It Li aaticipaed, the, unador

the prImc4ples of mual uevition, that thi should reqauira -re mergy.

It my h expected that tie up of flaeh-catem within which apparent

Motio e0 ie my be restricted if both of thN operate ina coajuactona.

This restrclttion should take place by raisls the lowr tluh-race threshold,

mod Lovering the upper lima.

Thirdly, borimonally barred grounds my be ued, fumthiag the

pound agsinet which the apparent meion Lto to be en. Thbe should

then set up LA the cortex ms a mnalog of the epetial mrageat of the

original dtiaulu. Accordio'gly, the bade of excitation created by t

etiulas lihts of the heta oetoa apparatus will h arranged parallel

to tham baade of eaxcitates and quiescanco. It would h expected,

thae, under the priaciplae already stated, that theam bad should for

perceptual pathMays aloes which te percept my trawl; thus, the pare

mcaptima of appareat iotion undor this coditiom should he faclitated.

This facilitation my appear as an increase A tohe flash-rate ramp

within which the eta-type mema my take plaee. Thi tIcremaeo thea

ramp should occur because such facilitation will toad to lower tbha

lower flaabh-rate threshold, and to raise the uppor flaah-rate linm.

To sumariLe these hypotbaese, them, it s anticipated that
(1) the greatest rang of flaeb-ratesa v itbia which apparent notio caa

be perceived will b of the non-fipurad ground; (2) the wvertically

barred ground will inmhibit to the latest extent thea perception of

apparent motion; and (3) the borimonusally barred ground will occupy a

inteamdiast position betwae those two.















caiRM U


APmiUTUI A noc uu



Thu apparatus divides into the flowiang: the electroaic witch,

the stimulus lihtsa ad around, and the recording aquipmat.

Ieta smatin a ,-e to,. --This part .5 the apparatus eoaslsted of
an electromlc witch controlLing two Sylvanla IUL30B electoaic glow

tube, the stimulus light sources. The witch used ms described by

Sacer (30). It I a wide-bod, bighlSaia patode r-f amplifier is n

mltivibator circuit. The Sptin sipals pndaued are sqmm, hlwint

negligible rise ad decay time. Cathode coupling 1 s used to the

U134 tubes to prmrvem this mvo-fm. The circuit Is tabu to I

kilocycles (kc); it i aormally operated vall withA thi a arga

Svnal flash-ns r000 an provided iLa thel control witch, giving

Mates from 02 flasheI per acoed (f/s) to 30.5 Lf/.

The second portion of thei appantum included tihe stimlu

lights, tbhe equipment used to support ad illuminate the groad, the

Ies associated withl tim 11130 tubes, ad the diffLuai saeuns. The

Sylvania 3113B lov tubes provide sharp respoao up to the Iaml-

tiso value of the tube wich to approzinately 13 kc. the actual

decay N rise time of tde liht stimulus iso a th ordar .5 2 to 3 miero-

eg. The llght output of the tube varies linearLy as the plate currat.












At approimtely 35 Uilla-aras (m.) it yields approximtely a daylight
spectra. As tahe plat" urmat to deemased, the ematted light hifta

toward the long wmve-length sad of the aptrna, L.a., Ceowaerd sth rode.

Firin of theM tub bmeeusa emratIe below S a plate curat. The

britaessO of thel tm tubes o equated pyeholoSiLally, rather than

by mwchig plate currnMts. It we found dtht slight diffrence be-

t tubes La IW* output at identical plato umnats preclude the

ua* of plate current meamuremnts aloM beiob used to equate the Lights.

Plate curretacs ta this study ware hbld btmem 12 aad 15 ma. XA

mating te 1113 2 tub" ta thae Litib paeal, a less system ae used

to provide parallel smissio of the light rays on the diffuiag areas.

As aperture w desal4md to limit the vLoual aale subtaonded by the

stimulus lights to 5 at ons after (a.) from bhs f; h owamver, due to

diffusiaOn thowh) the poumd Bglass *Cea the eal4 approximately

8, as masunred at the outer limit of the diug of light.

Three grounds waa oonstructed for am Ja this study. Oue was

plain, t.*, am-fisred. A sasoad comsisted of parallel, opaque and
traaslucet 7 us. stripes t a horilontal a-mst altarastely

played. Thi third ma constructed with stripes of am width altar,

matag opaque and transluceat varti al beads. These ground wn

coustructad by ult.i 7 a. strips of black construction paper spaced
at 7 01. to Tealex taSla paper. The black stripes wMr quit* opaque,

wry sha p. and of oqual width throughout their lsgth. The Veaox
traeinag paper provided a Braialess, tranlucent area thmuh which ma
prjeated the liaht from the 11i305 tubes, and the lifht used to











lmed s do grm uds. Tbmss agre ware Maloeed in a havy card-
board fIr The smuad amw all 26.6* a by 31.9 a&, mbtimadiu
o.? mgn aL md 13.P borimual veal magle at a. r am to i.

Thbe fproseds ae Osed i a slid. to the frost of 0 lig t-
ti4t bo. Uwehh coutaimd, ta AdditiMo to tm I11U 30 edwe mad their
less yr e mid aperture, a 26.8 a by 31.9 a mrdU-tesa dig-
&a&l creeam and two 15 wtt lnsdeaogmt bulbs, Sd ia color ad
tubular l shape, hic- -ae mame" aertically t m Mid. of the
scese. The brihemt s of ground illumlatia s eotsalled by
vryiq the voltage aere the tubular lim by mMs of a tarite tmew
trier. ThM Vltags miastaimed t rwelts (v.) thoughoi theo Study.
SIlulmiti rs ed for tihe grag in sadrs to manteia te *'s
dafk adaptation a stable leavl (29. 38).
The aentirea Light pMaml the ponad mpport, ad the a's china
rMest ve iaelosed to ltiht-tight tum1l emited am optical bmaek.
thbS disease Er. ta n o th tight p tso t 's ea. net s mainsaind
at om a A block lgdiam of the Ight pastl is sam In Fi. 1.
ThM optical aent, so l's boeoth, ad the emsia m en *al
MpabtsJ flat black to beorb tLght. CeoMldeble can Ms taes to
prwvest tiht IkA fm thd A'o bootab.-necsesriLly illumimeted in
the cours of the eMperinat-or fram satoe al sources. Lamg memld
euramlly wVry so edaptLaim level of the f Aiocn thw course of th
epartimat. It should be oad, hbowevr, that the smm detloN of
mtlam perceived drnoc psrtod looeer them 4 tmi. of dsk *dpsetieon
ito Vatively content (36) sad oa duration ie ot sipalficaely
ehbmnd by Cbmame to llittamtas witbi the mam emd (30). A




















A
B

C




D


1.-- --


(


)-E


Legend:
A R1130B Stimulus Light
B Ground (Horizontally Barred
Ground Illustrated)
C Light Panel Support
D Optic Bench
E Chin Rest

Fig. l.--Block Diagram of the Light Panel


'7


. -F X - -~1 --
^ U;,,-....!^,^ >-.i^"l;'L .,.*;- or-* *.' .,^t











block diagrm of the roM and apparatus Ia horn in Fig. 2.

Reordina amarstuOI.-A toelwaphic key vus Smted comvsulatly
tor a 0 within th optical beach tumel sad comoactted through a
suitable por supply to the recording relay of a Geobmad mardpsperp

taps siLal reordur. The a placed diati tive siPMl. the taps at
tLe begialng and sad of each trial. Thae Ure used to locate aeh

trial. During a trial, 9 pressed the key d6 as lts as be s
perceiving ea mtion. Siacs t3 paper tap mu fbd throash the
rcorder at a coasctat speed. ditaA aloneS the taps M traeelated

to tlm and t asmwunt of appasrent motm reported oader each coeditioan

ma them cnuted.



Observers eoasisated of 36 younia adults of eollep 4p who ahoaed
o obvious sips of brat damip.
lack uas given iatrucetLon and several erlentatioa trials

prier to th beSailnag of the experlent proper, Darln this period
m ground or rate used in the eiperimeat wa prested to the 2, It

was found chat met had considerabLe difficulty Ia diffsrstiating
lets motion from the stadowmiom pheo-aon at the hilhbr flash-rates.
Cosidemable training a B oued necessary for tahe Co n m r a
accufsrafte reliable report of his perceptions. During thee orientation
trials, the ft an instructed In the use of the toLegaph key con-
trolling the Gacrrand recorder.
ach was given four ail. of dark adaptatim prior to the
beginning of the axperimat proper.


















----I E



__- _- -- --I
I







GI










H




I


Legend: A
B
C
D
E
F
G
H
I


Electronic Control Switch
Gerbrand Paper Tape Recorder
E's Position
Light Tight Equipment Booth
Stimulus Light Panel
Gerbrand Recorder Control Key
Optic Bench
Chin Rest
O's Position


Fig. 2.--Block Diagram of the Experimental Room


r




B





C



D












Of Necesity, te istructleeu wnre varied ta coa t for sch
fo, fr some mrs or familiar thua oteMrs with the phbmmmonc. In *&1
caes, the semntial Aa r costant. Nore acoumt reults
anre obtaiined by equaliiag the practice effects am n ackh j we
almed to beco thoroughly faUliar with the char acteristics of atas

otiton at ecb flash-rate. Although the coatefnt of the imtructtiom
wms varied with these f. the construction wus desimed to Ilmtill a
similar UI& n Seach Following this period5 the eparlautel

obmservaton begaa.

re wn asipe4d to a Greco-Lttia Square ia sriatim order (19).
(Se Apoendix A.) Altbiouh Glbmert (9) had shows practice my be of

eom imortanc In th perception of apparent otia, a mon mNcamt
study by Leichenberg (27) ladicated that meaa duatiaa of mthos os

mat sigificastly different during throe successive practice perlods.
Bwr. teM ue of this type of expOrlMMtal delga provides a control

of thiB variable, sn-e ea ch round as preseted ia each ordered pUsitto

sa equal muter of times.
The use of this experimental deasip also provided the mcedule
for the presnomtatioa of all grounds to the k0 The prmertatio of
each ground then was of a desceading and ascandiLa series of ami flaeb-
rates. These rates were 0.4, 1.5, 2.5, 3.5, 4.5. 5.5. 6.5, 7.S, and
8,5 f/s. Th use of couaterbalaaced series ras daJalpd to prelude
any eyeteattc error on the part of the I due to aticipatioa or

pereveration (39). All 21 wre given these series for each ground.
TihM, obsmrved a total of 18 periods for each ground, or a total of 54











time for tbo thre Srounds.

During each trial, the .0 w Itructed to hold the teleraphic

key dn during the tim e he perciving Beta motioa, and to rebs

it iem the perceptio mas of two Llhs flashieg, -m fixd light -

with the othe off iL ecyet, or the shedwemotion phmmsn. Ite eM

of the key I this maer placd a ditincti mrcord of Bet motion

p.o tbm GOrbracd tape. Siace the tape o drive& at a constat sped,

simple trnafonmeLio comart distance almg the tape to time

meusImISt. Each ainute trial of notio a thm covered to a per

cent tim by the equation:


(100)


In whch to is the ammunt of apparent motion each subject pmrcetivd

during a trial, do, is the di.taaca along the tape during which he

held the ay dews (mu perceiving noion), and Dsm Is the total distance

aLog the tap. of each trial (tiLma), The product to pressed as a

preetap of the tin l which appreut utoti as perceiwd.















Cut" III


Bach ms presetd all of the tm e arouade. The order of
presetation ibm .o th Oraco-Latia quare (Appendia A). Elm

flah-zneus, ar ngod in scmdiang ad deeeadi a serio, mn umad to

dateinam the upper ad lower theobolde, opetlml flb-ate, ad tO e

raIp. Thei four obmratioual wriables coutituted the masue of

te f2* pemreptlon of apparent ties used iAn this tudy. Th mount
of bte untio em at rch rate sad for eae Pround w dtemrInd fxw

m -iurm t take twro tbhe Gerbrad aed-paper-tae and thM convrtod

to tim. Thee iwasure mo etored ia a table ukhich wa used to

datenmlne tI tbrosholde by liear Inaterpolatioa. Optimil otio wa

derived rins the table asa modal emo* The raw was derived as th
difireace between t upper ad lo er threholds; it thue repwisets a

flasrate nrp within uhich apparent Iotioa my be perceived uader

thbse coaditioa. Is dieteiLai. the thresbolds, the 50 per seat ima

'm used.

Several criefria won found necessary in *cremula the data.
It m considered sueatial that each 9 ee lon for. at lest half the

tiU seO w rate. A second cgiterion wae that alhold be able to
report coaiste aly. Thus, n 0 who exceeded te tbre hold, eaetimed

for flaehbrate above the threahold. end the a less thaa 50 par mast
Uotl.o, only return Above the threabhold, wa eaoidered met to bave

22











11llomd the directioas, M liminated fni the study. for ost

I LOt go, the study, a replacemat j ws completed. Th criteria
for tOe rplagemint 3 Mre the s-aa for the orisinml 3. ad the new

Ses placed in the m Cell of the meoe-Latl Sqmuaem.

T upper end lowr flauhmen theWholds. optIml flasb-ate,
and the rap within which Betsa ,ati Is e constituted the maMsM

used ia this study. The lo- flas -nate threshold for BSet atlon is
defined as that rats blow which th reports less than SO per cent
apparent atlon, Below tchrashold, psychologically, the peoept break

dawm nuto two lIsh which are alternately illuinalaed. Piilarly, th
upper flash-rate threshabold my be defined as tht rcate ave which lets
aotLoa is not sen. Tor this study, "not seema" l defined as a report
of Bata atioa for iss than half the tim LA any m trial. Apia, a

the tbroabold the typical Set mtion percept is replaced by a. entirely
diffiberaat Me; ta this ca. aJ reports seeing tuwn lights which ara
alultameously a anad flickering.
optimal flasb-ate is defined as that rata wich produce the
reatest repotted amuat of lets tioa, eaxpresosd a perocetap of

the total. Thee, it is a rate at which thbe atla i seem mat cam
tiauoesly by the. ad to owLa b the mtloa mat early approaches the

percept of real antioa.
The statistical aalysis of the data included tea coutatlom
of the mas for all the groups for the three gund, the standard
deviatioans of the distrlbutieons, the standard errors of the mama,
Parsoa product'-umnmat correlatioa coetfficia.ts, ratioes based oa th
correlatiom coaefficients, ad four coaplez saslysem of wariance (19, 2),











The me aen coi.ted accordln to the tmndard fomula sglven

in Hcm:ar (22) and are report in Table 1. for the lowr fliah-rate

threshold, the o rate my be latrpreted at that value below which

Beta maotLon is ot e Thus, ar the Man-fiaund Pound, the wvle

is 1.71 f/E. Th value of te low i r Lia or the vertically barred

ronad ia 1.77 f/, aS for the horlaatally barred ground. 1.75 f/s.

The upper ehruhbold's om value my7 be iaterpreted being tat value

above which Beta notion i aot s For the a-figurd ground, this

value Is 5.26 f/ls %bile for the horisontally barred ounad it is 4.68 C/s.

and for the vertically barred ground it ia 4.62 f/s.

The optimal rte ba been dfind as the rate at which the 0

sew the greatest per eont tie of appunt sciatm, using the udal value.

For the non-fiured gmound, this wa 3.21 f/I. for the horLsonutally

barred around, thi value as 3.10 f/s, while he fo t vertilcally bared

ground It we 2.93 f/a. It we at these values that moat ft iw se

largest amu t of apparent a t oa.

The ravp, the dIffe nce betee the upper and lower llmW,

smuries ose a single aliue the reap of rates in ehi. study at which

Bets ntio ma eeno. Thee rnps, al.o reported in Tblo 1, Jor the

on-filgured ground as 3.55 f/s, for the vertically barred grpoud a

2.85 f/1s, ile that for the horiamtelly bred gromud us 2.93 f/s.

It wa desired to obtain eaMn estate of the dispersio around

these values. To evaluate this, the standard errors of the Mana on

coqutod (19, 22). Thae gie as ntimta of value withi which, at

a stated fiduchal limit, the true mao of the universe of mans gre

which thes obtainMd mes Ian daw. gettiag these idacial litt













NIASUM OF 3A urIm AICOMDIN TO 6m IUINU


of-fliuvd 0oui d 36 5.26 1.07 0.18
Iriamtal 36 4.68 1.44 0.24

Vertical 36 4.62 1.46 0.24




oanfiword Ground 36 3.21 0.66 0.14

PArlaim l 36 3.10 1.00 0.17

Vertical 36 2.93 0.80 0.13




esM-fLikrd Gramd 36 1.71 0.70 0.12

ainMstl 36 1.75 0.60 0.10

Vertical 36 1.77 0.66 O.11




Uoi-EpIred G0ouad 36 3.55 1.36 0.23

Borlweal 36 2.93 1.67 0.28

Vertical 36 2.65 1.62 0.27










at I d", it my be stated tt tewm true ma rat for the upper
turesold of the ue-flred Pim"d m 5.26 /s*, 0.1 f/ie. Tno
lwer threbold me 1.71 ti/, i 0.12 flie, and the uao optiml rate wu
3.21 f/. I 0.14 f/i. The mop *I e atM witbhia hie appaeet atisom
iL es sM 3.55 L/oe 0.23 f/i. Similar staemnts M y 0 mbade for
the mean irate f upper tnreseolds, lower thresholds, optlml utots
Mand the ans of ates vithiba vhich apprame a ou e seem fUw toe
ether srmdI.o
The stadard dvliatiome of the diatrihutlom for te various
pomedd sad measures of otsa mtim .mN computed ccordiaf to tw
standard mtbod ivwen a Itdemr (22). Tb.. values a suam rsed La
TAble 1. Thus, to tih upper threshold of tlhe mmo- iSuNd oummd, td
mo om 5. fi/g. 1 1.07 fi/. Similar iaterpetatlml hold for thm
other values *d fr teM various prumd.
The nmerb of| eaterLg Late thes emputatioms ms, la 1 all
condition 36.
Iamios puodnse-mm t com latio coefLtlets betenoM pain of
s s 19 coupfted according to McHImr's (2n) mdal mad an
reported to Table 2. Tha my be sterpNted as msuroe of tho e-
slstemey with lch theo J reported frn. one mauMe tm amhoter fbr th
wVarious Ponad. They ae ia a maI a mamsv of the stuiabLty of
to measures thlmwlv if it am be assmed that Wt mwne egsggtemt
Sa their reports. Presmbly, perfectly stable mes*M. egfficmsat
of 1.00. should yield the em performed value irmpetive of tho
coditio s unter Ihick it operates. Any Laeo istegy tbm mild be
diverpace owmrd sero Itm thie correlation. As my be sem from te














TAKSL 2
waxer or t oassvtwna
CAMR-In 0W omu2 aHM Ot LOW AMD UPU
PLU O-MIA TBaOURMI ONtiiL d H. AMR RON
OF UIA 0IXOII


MNeasure Ground Vertical lorLsctul
6road Gcrmd


Lower Flashb-Rate Threshold Non-figuroed 0. 72*0 0.64**

Vertical 0.630*


Optimal Flasb-tate NHo-fipurd 0.41* 0.02

Vertical a 0.48*


Upper Flash-Rate Threshold Nom-figured 0.533** 0.53"

Vertical 0.56*


Ungp of Notion Ron- figured 0.53** 0.53)*

Vertical a 0.62"


*Slignificant at the 0.01 level of coafideaco, df 36.

4flipaificant at the 0.001 Level of coufidsacA. df : 36.











table, tbaeem measures are fairly stable with only mM oxceptios. This

*saptilou occurs at the optimal rate for the mo fiuNred grouad

correlated with the a' reports for th horlsontal $round. Vrm the

other coeffliuens for ths murs., it will be sa that they. while

signLficaat, ar significant only a *uch lower level of comfitdeace
than a1e thu coefficienmt for the other masurea. t would appear, themn,

that this to the least stable of the m=&ures used. It should be

rgmutred tt this mwssure we computed fram a odl muber of the

per *eat of tionis eem. It we thus based u"a only oa scoTe for

each _0 the tkcmdboLd values mee basod ups trem vluws by msn of

a limear interpolation Egos the dots as entered Ana computatsio table.

It ws oed that bo iasu ubility ishbeat in uaeia only om seomn U

probably Indieative of the oureg of this iscomaiteey of the g*s

report. It my be co eeludod, thaee, that this Ineosiseacy my be ms

artifct of the mhtbod of coputin thUs msure. It my be further

aomluded that the other asues are relatively stable.

ThM barSoO pcodut-mmst comlatiM ionS f ficieMts r urther

evaluated by mes of the A ratio. TMh fOml praseted is Mas"

(22) wee u"ed TbMe orrelati coefflueimts w tested iit the

sull byWivats (that thoe R we sigo ifiSeat diffnwms btwee the

obtained corelaion coefficieMs and ern). In all but the m case

already noted, the null hypothesis we rejected at the .01 leeL of

eofidence oa better.

rout couples amalyee of varianc waere completed efor this stwdy

(19l). Ia *ush of tbome thar rs three fixed and No randomly di .
twibuted variable. Tbhee analyses were desired to fix tbhe meO of











Wriasc of tW msaunm. Ascolding t the .prlmmaL delMp umd,

the m4itfLca"e of the ftetes eueld h ewL etd e three soue-e:

the xouads, the order of ipsetatia. mned the buhbl Late"ac.tim of

the doadA ude order of peesatioa. the ummea Iomer t"h hold,

upper cubxehvld, optimti nts. sad a1p of aste vitbia whicbrh ket
ti a e mes, man all dse4igated sa depeadet WMriable; seek

MUsea provided epanst Mlyie of Varisae. AGroumnd ee order

of aemletton two of the thrin dimaeiomo, Mn find varltabi.

The third wrlate wee t ade. vaiirable, replicaios This types of

diw4p pmmiai the evLuwAet ofe the rounds, of the ordr of pm-

en6taLon of the roaade (pctiLoe), ad of the iatmnetiloe of theme

two. vaLuslotia of Indvidual dLibnmmum As ao obtelabte. It -a

esumed that iadlvtdual d& eH aem would e renadmly distributed sad

would theeforn et sme as tportant comtrIbtitasoto ta rialaeo Is

this deai*. Slace thee we oly -m admivLdual aomiped to esb c ll

wader tWhi Iurlatal diaa, v.ithla cell vwlamr e w men.

The ixrst of then aMlywes, that of the lamr thbehoLd by
proumws by order of pneuataclo by neplicatioan, o prMsated Aa Table 3.

It Is OvldeMt that then o e eo tatisatically sisfi8cfa sources of

variace betams the wrables. It my be Cacluded that graoMd ma

not SWalfiaut variable Ia the detemaLnmeti of Bata tles for the

maumm ud at the leor threshold.

It bshUld aleo be notd that there 6 N t0 etotcalMly stoi-
fi3t pcactLce effects (order of prentat ion). ZTime control of

praretie effects by asailpmmts of i ta erlatim order to Geno-

Latin Square affective.
















TA 3

AMLTSU OF VARUI FM VAM&M NfOSZW IOMB
%R4A?-T r TUSMUl: GMOmS X OUG Of
vinsraM I UMATIHmi


L... l Il1 4 a I .
gat.o *


Groumda (a) 0.07


Oarf at ftese.katio (0) 1.54


Replicationu (8) 6.30


0 1 0 0.37

a X R 2.47


0 t a8.35


SX 0 X 6.78

VMttS Calls 0.00


total 45.88


2 0.04 /"u .36


a 0.77 moino/O .6


11 0.57 -


4 0.09 ,gMo/ a .60 .
4 O, .0 -

22 0.11


22 1.29 -


44 0.15 -



07

107 -











TMe Eflets of order of pneemtatda ad of the greed upoa the

ar--aumt of optiseL fLahb-ce,@ of apparent mion an preeted in

t*bLe 4. It my be ea that ate oR the wvriable approached tatsUti-

cal eitLfieeo. ThlmboN, neither eAder O. pseetttoL mor grMed

me a lpificaat nurse of varlloa ia the doteairlMtia of this

mene Sf Iota-type of apparent notion.

The third an lysis of vlace is prese m d A table 5, lbs

Lind wVriablee wm Order of preesmat ie and peeod, apleaetlMe

fomd a readomily distributled variable. The upper flas-zta thrhbold

of leta ntle "a 0e depedment wvarisbLe. A my t neao ve the

table, the pouae wmm si*lificaL t oeres of variesee upo the Seta

moete at if t upper th, Ihold (jt < .01). It my be eConcluded that the

groat.e wn a lipfiiact deteriminat of this mean. A pdn. tiw

oerdr of presestatlm (practice effect) wa no6 t el tatleast sorse of

wartaceM, nor te e iaca L ctiemetu. Th pound aloea lor tm ajmr

ensures of wVariance.

Thte t analysis of variance ao the rtup of otes within hich

IesU tla U" Iose I presented Is Table Of the sources of vri-

me i thio mWn of oet Motion only tha pomad wenr tatistically
alplfican Q < 0.023). It should agiaM be mnted that thte w as

*taistitiLey aignificant variatio attributable to tbhe order of

proeentai of dse roMads. We we the inatactlon of the puad ad
oeder of preseatio.. statietically significant. F this it wme

eocluded that the practice effoets n effectively controlled to etis

emperlmntal deslg.

A series of 1 ratios, corrected according to cmemr's (22)

















ThL 4

AL.Y3IS OF tUUAE M 1 AIA&U2LBS MODIFYl
0o]DiL rIMU-5AM : GOom I OR= o
MWnLUN Oi a MPLIA2IOUS


Sourer ** d -e ? ,T J
I
0110~~~~ Mozot 0WmN -


Groumad (a)


O1l.t1 of ?wa tatou
(0)

m0, Lust am


a x 0

* X 0





*J X X ft


vlitbin Calls


Total


1.40



0.06


U.J0





12.71


35.80


23.54


0.00


67.06


2 O.?o ,/m


2
X



4


2I


22


44


0


107


1.21


0.03 moo/sn 0.02


1.07 0


O.4 o 0,-1





1.63 ,
0.4 maom, 0.4


0.54




* a a


*

al















TALUi S

AMULYIUS Of AXUK3 M VAZUDLM UDDIPTIMWl
OWR FLMm*UT Tin-OLD: OBOO X
M OF PR1SBRATTM X RUPLCATbM



Source as 49 gS
MUiG. .


Grommdm (0)


O*dar of Neuetatlom (0


aopllecalma (t)


a X 0



0 X R
a x a




a 1 0 x a


Ltlina Cella


Total


8.90 2 4.45 "/-gl s.M6


) 0.80 0.40 MO/,OR 0.10


45.90 U 4.17 .


4.16 4 1.04 ,O/O 1.17


16.61 22 0.76


87.32 22 3.97 *


39.04 44 0.89


0.00 0 -

202.73 107 *


0.01


*















TABLE 6

AULT8YS OF VAJAiUMC VAUIMS NO.1rn MW I Mf :
GKBD X t OSB P'JItT nSSS x0 XRX.IC4TWS
w02=1 ov MUIT IOU I taUJUIVU



ratio
*wrc*~L M J^ ^

. . X ; 2 . ... . . . . .. . . . . . . . .i 2 .


Gmuds (a)


Ord" of Presestato (


Uaplicatloao (a)


0 X 0




0 X 11


a X 0 X a


WirthLa Calls


Total


11.07 2 5.54 Utbu s 565 0.025


0) 1.37 0.68 MO/M1 0.11


50.10 11 4,.55 -


4.92 4 1.23 /1. 05 -


21.51 2* 0.98 0


132.13 22 6.01


51.49 44 1.17


0.00 0 -


272.61 107 -












ibnmLte br comsrltlou u cequted to detenme the ia fletficce of
dif fm between th memos of the Uameuf o let muoti. Theu
anre presented in Table 7, Tbeem a e siIficant (C < .01).
Two re at the umpr trotsMLd btmu the mea-flpond d th verti-
cally bared pmed, ad betwmes the se-figured amd tte hborlatelstly
barred 8rmad. The third wu for the mug of matm betwas. the
noe-figurd and the vrtically barrd peued. Two other I ratloes n
significant ( <' .05). for the lower lims ta he ialflcant A& w
betM the vet tcatlly barred mad te umfisgured ground. For te
sna of oties tiM l4pifcat I wae b -P-us thebr horimtally barred
aud th meom-ftiud reued. Por thu other j stleo, the mal p-
thesis umt be acoptod, mand it onmeltud tit thlt grounds va
mot statLecieelly ogaifticant mourn of varianmce or the maw test.

















TANS3 7

IUWIC&CI or TIE DRIIUU suW5N TI= mm 0?
8m ~cs w Diumwset w Wmm ri n or
f ~dm/ MAB 8rS xU0HOrio


emesre Gxomud VerticAl noriLmmtal
Ground Grmnd
i 2 Z l 2_ 2" _ 12 2_2 2 i ; . ." i _: _' . .. . .......... .. ........ ... . .. . ..


Loer Flasb-mate Thehold





Op lmil rlab-te






Upper frlahborate Tbreshold





Rap of notion


Noa* lW"Vd

Vertical





Vertical






Vertical



Nom-fivred

Vertical


2.140*

o



1.87
C




3.0Q2

*



3.02*


1.33

0.71



0.50

1.06




2.76*

0.26



2.46**

0.46


*Snifimcant at the 0.01 ilmi of coefldauc, 4U 36.

*$4aPificant at the 0.05 levl of coufidomee, df S 36.















caPrn iv


DISCUSSICE AMD CONCLUSIO5

The over-all effect of chamA ig roued for the upper threshold
s" s4Lfcamat statistically. This m7 be intarpmsted as that the
grounds 4 chamW me o Iai t of seta wtiLo. The difftnemca betas

the eonfigured and te borisameally barmed, a4d the mm-fiSwred ad
theM vertically barred gounads, we *alpificat. It me Sfeued that

the men flmb-ate for the mo-iLpmued grand we 5.26 f/s, ile the
hmriaotal d vertical rounds wae 4.60 f/s aed 4.0 f/, rempectively.

In mintalsam moti e pereepelom higher rate f tlon msw tolerated

by the for the plain isn coqaprime with the figued renda. Thaee
diffterames wre etatiatially aignificant. The finding is comeesan

with the hypothesis that mren mtloa my be obtained freom the ao-
flrP d the from the fgigud rouadD. The hypothsis tea there muld

be a differenatial percfptlm of Bata motia fr th horioastally barred
as compared with the vertically barred ground a rejected.

The other dapedent variable for wbLch groud ma ai4nficamt
-m rMap. The rap as odifled miatly by the olevetion of raete in
thbe uppotr Imit, There a o s -uatitlaically siguificaat diffeesace
between the mas of th nmaures for the Svonada at the lover thrsehold

mor in the optlial flnabsh-mt. Th are a statestically si4pLficat

differemaocem between the hboriaoscally barred ad the vertically barred
grounds.











AMoter ftIftl of iptnumoe me the comusiltcy of Smund

effects for the msures of Beta motieso TIMhe Pest p.ee"t-mmamt
cevaltiLoa ceeofct-f vas oileIasft. Fer sewvaL maotes,

emept fr oe-tala p ed ffieoe sa eoptima wats, do obtalmd j betwmn
the rn-figured aed wrtically bamd gwed, sod hbetwe e wvirtleally

sed boheoteUally barred gpMumdA s esignificat beymd Ow I per ant
lewl of cemflideme. Oly thei corrmlatlon between t nmm f1i4red mad

the boret-ally barred pmudel for optiml aflash-rate m w o swie lflo

cot statlLstieally. Hoeowor, te highest WM eObtalmed t te iLoar

thbehaeLl. it my be laterpcefd as adtcatinat that the k we met corm-
isteMt at the lwr tdhreshoL. Thou sek mm ot e LeteM t af t dt

optimal flaebh-mate us n.

it would apa. thes, tIs he bi of thMse results, that a
flaeh-rate smt brw a ecrtala ai.imm to be percelid as apparet

mtLen under the peinm-tes hat he bw h use A* this st*uy. The

vry ih somaiLter y .o thO Je' 'Otport at the lomwr threshold slpi-

imed ( mee t %) h ete tat property of thi taimmf Those
psd eB as Ip o ofv lt efect e tO loer theshold. Oi ths be uos,

it sms mt reasonble that moe sbhld look fwr a phyLolosteai tether
thean a perceptual epla ation. tuo uierstamd thi"s portion the

Phmenomn (2).

IS cawetuctiu a pbYeiolo0,cAl model to account fb thLs part
of thbe fladla, a*a hypothoeesi of a smwation of anurl lopulss taking
plaes ia the cerbral cotex vae ausmd. On the baisL of avaLable

evltdmaNo Chi M safe assumption (2, 23). Now, tm trhe eye is












presented with two altermatiag stimulus libhts fomia the basis few
Bata mtism, te ligSht frA each of thbse lihbts fallia the =etina

wentesa m ounal impulse uhich is the tranmitted alag th e visual
patbusy to the visual Corte x, near rtoduma's area J (23). the

evidenMce Indicates that each time the light flnihe, tain of aorti-

eopstl moral Impulses is Wmrated, &ad preumbly ead i theb

viimal corftex. According to L, de ob's (23) statistleIa model of the

viAsal patlmy, these Impulss my be retaiMed to discrete pathmys by

tho procis of untiasti sa d ainhiblitioa. The model Masses thtt *

relatively stroa Imapulse is Messay to fire po&s-eyaoptic, Corti-

copetAl sutoe; this strength of mpales my he called the "noemTl" oe.

Tho neural nt of the retlnee ad cortex are comected by se ries of

mourms. A impulse, radiating long thes bracles, my not haew

the treoath necessary to fire ser than one, directly ceemtod post-

synaptic neuros. A maunm barely dischari above thresbeld althavo

impingtn eotbers my met tire tbhm This procesina emvs to pw

erv the discrete -turn of the original stiaulius object.

Houre, the ondal assm both tporal mad spatial mstim.
The first assumptio states tt, t I f o mural Impulesm dictsrziag

om a poet-syaptli area's dsmdriteM ia 4 particular temporal order,
and neither of htch a In themels af sufficient Steity ato fin

th pot-sayMptiLc Muan, a smulat my produce a upsrthrehold
inteneity ad fin thbe Moarea. The coed asq1tas of spatial

u tlmtion states that given twe ubh hld Impulss *5beh arrivw e

sepmarate dedrites of thei peost-symapeis maso. at ta same tima, my












MMtItS through CAs post-synptic amUM, and thus fire It. Zt esee

probable that this forn of summtio (spatial) ina th visual Syet

operates to provide s smoch, filledia proJectLoam of the *xantuml

sUmtiMuls field, while h first, tempf al summtlin, opemts to provide

* smoth, coatuou percept of retL matio a the e ternal stimlua

field.

In this mldal, as te stimulus lights far eota mottoi ae

driven at a very low flash-rat. e.g., about I f/a, a wove of ezeitcatoa

to sat up in the retina br eh flash of each 1ht. ThLsp, An turn,

fires tbhe succeeding corticopetal atosm, amd the ISpulse ewatually

ads a the cortical anero Bat there to aSt a sartae of imnlass

set up which Impiange on tb dendrites of the sdjacsst cortical earu s

ia the visual striate area. With such a low ras of flae g, these do

set gae tBhe sequenace apparently sded4 far mmatioa to take place; Mot

are the twco timnlus lights close enaouh together spatla lly o that the

impulses aeued by the stiaslacion of the retina impqo an the sem

aterasunciLe aumaS. As hs lash-rame aincreased, do Ipinment of

these impulses a adjacant amsumos becAmes mrsn and msm equt;

finally, a rate is remhAd which alLows teporal summtims to tate

place. Thm tbhe ara of stimlatiom is sped a little, aed other

sets of intet uactaL UnUcous begin to be gives on subtehbotLd tima-

ltion. As the flash-rate is further tncressed, the em sbmeiss tan

volves mt sad am neuonms. A locs of esciteaciLoa is at up. Ae this
loc As o larged with Increasing flusb-cate., it my begis to Isto eact

with tbhe Locus wbich he beem e up by the similatiom of theo emcd












stimluo light. really, he tw loot la tho usual corax Interact

through a "baWa of imeom betime t- ad 9- 1os t dancdte pl"Its

an present. The percept under thawe Coditloams my be f a siagle

liht Wich wiags back a4 rSths, ftlwi toa Its tajectory the bnd

of stimulatioa wlhA hbe been easoed by the inteactiom of the local

up by MdA liht.

This neurally orulated eaplaaatioa se. to tit the fects oebo

taimed ia tis estly for tO lamr flash-m:. thresold. Zt is cea-

eas" with h Iladlig of th hijhest correlation eaefficlete at the

low flab-rca threeoLd. After all, th asaeVMs sysPtM s eM -

to bh ra mtr stabla tirb comteAe wuder which mtstia. sm take
place (23). The Interpretatioa sapes to be In areaat vwitb the

aalisee of vrisaaoe the & toot luadiLap both of hich shew that

then IS ma sinificaMt d411fvema. for paouad at the lomr flasret .

threshold; U is flaeb-ate hich uL tohe loportant paruminter, and t

the pactterniag of tOe rounds throubh which tthe at motion takes pla.

It Sl, thmg, a neal. nst a perceptual, pbnoMen uieh takes place

at tbhe lomr toeshold.

On te upper limit of apparmt otiontl there afn stAistt lly

s*lfaleat difuresC la the m ss *I the namoio seen aiast the

fhxd urmmds used In this study. Thae dIfftnacem an sock case

balee tO l 9iured a4d the mm-fiured ground. In coaperlas directly

the obtaed mmns otr this esur of apparent wi aoclan., It e emund

that Mrs motion Ie seen e the non-fipred coepnd to the figured

grounds. It was arlier hypoth"Ied that ths m=iht take place s tho











baiats of (ismorpkic] projfct&L. of the stlmLus pound to the cortes

ina such a way that the moEiaed pomd would preset the psa"t

possible muoiber of altormative ptbmYs by uhih apparent mWtIO. could
take place. Tberefor, -on metio should be soM ona this th m on the

other tao poumd. Vhbether or mot th n may be strict "tsMowphUi' of

the vsual pnmMd ia All It particular my7 not be i rprtd dirOCetly

froam ths study. But by attachl the strties of epoque paper to the
proundh the illuminatecd aea 0MJ reduced. One oeplamtlo of the

itdlop my be that summation fubctlae at ad beyond the upper flas.

rte throebold ona temporal basis aLoo. Ve(l defined liU flickeL-
USg almost sialtam ously produce two seMusatio. Smmtioen by area
providing these ames are spacally sepcraod. fails to link the aw

defined brigbiuas lvels together Into motion peresptloa. la varying

tIb Iatensity ter the stIUtlus lights. Smucr (30) found that latesity

did mot affect the am duration of mtioe. It sMem ressmelbe to

relate this fct to this problem. rertepe gzouad latnmity, aot a

sifglicant varlable ha itselI, could eonso only 40 a smtial tvariable

if it operated at all. The higher stiulaltion rate, ith eumetloa sa

a temporal basis at the cortical level, produced two flickering lighLfM
and tihe upper limit h reality reprsemRs a lovr fusiola threobld of a

special type. The ground propert le oren upposdly efective a
possibly altering ftusio in term of temporal mmnmLeai. TMe study
suggWsts a central moasitiaeion oa e temporal basis at the upper mrgia
of notion- motion thresholds. The hypothesisa of temporal sm tilo

advanced by Borne, et a) (15), is partially supported in this study.















CdAM V


Tu figured grumade, -e vertically barred iat a second bort-
oatally barred, ad a noea-flamd grmmd were ueOd to dartermi the

Mn upper ad lowe faMb-ate tbrwsholds, as optiml ra, s.d the

ramn of flaeihrates within wIrch lota appretc nioan my be ams.

en"ral byotpb0tes a developed (1) theben maould be Little nation

esem with the vrticaLly barred ground, it serving a a perceptual

barrier to the production of apparent noticoa; (2) that the horLmmtally

barred rand should have -m intermediate aounat of apparent mttLea,

the hborontal batsn pValll to the path to be takme by tthe goe notice

fursiehli perceptual pathway for notion; and (3) tht the as&-

fipUtrd around, by providiLna the largst free area, should provide tohe

maxima aut of epparenat motion,

The resulting mseurs wnre subjected to mevoral tatistical
analyses cesiating of the manj, to standard deviation, the standard

errors of the mMn. Pearson product-ment cormlatiom cooefficiets

betMeen pairs of the measures, ratios to evmlua the igsificamce of

the difference beotwas the obtained mmn, sad four cmale. amlyes

of variance to evaluate the over-all ipnificance of theo sources of

variance, and j ratios corrected fer correlatio to value the

diffeenuces betema the mass of cte measures of apparenaat otLo, for

36fA.











It ms found that no statitically sinificant differences

obtained between the grounds on the lower threshold, and for the opti-

ml fLaeb-rats. Statistically slgificamt differeMces wre found at

the upper threshold and for the ran"e within which Beta motion my be

sema between the figured and the on-f figured grounds used to this study.

Mo statisticalLy significant differenceAs wero obtained between the

baorLionmtlly ad vertically barred grounds. Statcistically significant

we re found betumn all the pairs of manurea except for the optimal

flaash-rate. This finding wea related to the coasistency of 0a reports

and thus of the stability of the manure8 used. The finding of

statistically ignificant differences between the figured and the us-

figured grounds at the upper threshold wre related to a theory of

asutLon based en: (1) flash-rate, and (2) the area estimated.

(This finding wa also related to L. do No's theory of the statiatlcal

nature of discrete etimulati on n the viLsual pethMys.)

A Gestalt interpretation of Beta-type apparent motiona an the

bassist of Mfg and of isouwrphim was questioned. Temporal

processes at a central locus or loci my more readily be used for motion

and fLicker-fusioa interpretations.
















APVUMUIX A


GIAECO-LATIN SQUARE MhSIN


Order of IBackrad: subjects
Premrtat ------------------------ --m...
PLain Verticai HorLaomutal


2 I 2 3 1. 4, 7, l,
(Plain, 13, 16, Lg,
Vertical, 22, 25, 28,
bortLaotal) 31, 34. 7A.
25A.*

2 2 ? 1 2 8, 8 ,I
(ori.mtal, L4, 17. 20,
Plain, 23, 26, 29,
Vricl) 32 35, IlA,
Vertical) 20A.


3 3 1 2 3, 6 9, 12,
(Vertical, IS, s18, 21,
orCoMtal. I24, 27, 30,
Plaln) *33. A36,
11, 27A.


tufflx LUdicates renplac-m t subject.















1135u1c55

1. Bartley, S. H. The relation of retiLal i11lLuatia to the
exparinBc of MveSnt. J. lAmE. hi .i.., 1036, IJ. 475-455.

2. Sartley, S. 1. Vision. A StIdy of Its aiLs. Bew York: Van
Esstrand. 1941.

3. Brosn, J. T. Thresholds for visual mvement. ichol. Ferech.,
1931 J&, 240-266.

4. Corbia, U. U. The perception of roupin i apparent movement in
viual depth. Arch Ptncbol1. M. Y. No. 273.

5. Duacker, K. Uber Ludusiorte Bovieupa (Eta Beitrag our Thoorie
optiLach Vahbrrao aier Bivesuag). ftycbol. forech., 1929, ,
150-259.

6. lli is, V. 0. A Source Book of G ftalt Psvctlo.y. New York:
harcourt, SBnce, 1935.

7. xtar, S. KxpeirLmaalle Uhtersucbusaaen det eanfeachsa psychischnA
Pocess. Ill: Abbandlug: tOr permonlictela Gleicums asiter
Tbeil. flua. &Archb. l. nyiol., 1875. U, 403-432.

8. Gouarali,. J. A. Apparent w -m at to relation to heayMu and
beteayMuus stimulation of the cerebral hemispbhres. JME,
Z MI. It",. af 592-59.
t. Gilbert, G. N. DynauLc peychophysics and the phi pbenamon..
Arch. Pychl NU. ., No. 237.

10. ottschabldt, K. It: Uber des Iuflums der Irfahrun8 auf die
Uahmnmes n von Fiurem. P. cbol rych., L92G6. ., 261-317.

11. Gottscheldt, K. IIt Uber den KLnfluss der rfahbrun auf die
wahtmmaMs wovn Firens bD jl; goZo ..- 19293* 1,. 1-87.

12. Guilford, J. I. and Hlson, ,* Lys mveiunts and the phi-
pheasomMon. J, hyc ., 1929, .j, 595-606.

13. artrams, 0. V. Gestlt fvcbolo; A Surveym of Facts and
P.!ncpj-. Ne York; Ronald, 1935. Pp. 23-30; 125-126.
14. Hartmu n, L. see Vareclmisuapproblems. >,Ynn Frolch.9
1923, 2. 319-396.

46











15. orne, 1P., Wilson, S. R., Saucer t, T., and esichbnberg, 1.
Temporal summatioa as a thoreticul basis of apparent nation.
Paper read at Southeast Psychol. Assoc. (Physiol. Sec.),
AtlantaI, ay, 1955.

16. Cofta, K. Uber den emschen Kreiabognversuch. In Koffka, I.,
Klein.e Nitsagteui aus *w Peycholoiachmen Instltut dir
Univermitat GCeisa. Pmnhel. fuorch., 1922, 3, 144-155.

17. Koffka, K. FrtacisLes of Gestalt PTvcholoe. w' York:
Harcourt, Brace, 1935.

18. torte, A. KineustoskopLche untersuchkngn. Zeit. f. ?sychol.,
1915, 72, 193-296.

19. Lindquist, 3. 7. Dnjitn and AMilyais ol gxertjnM in &yYchoPoay
and Iducatitoo. Boston: Houghton, NIfflin, 1953. Pp. 220-244;
253-265.

20. Links, P. Die Stroboakopischen Tumaclbsugsn and des Problem vn
Seweums. ychboL. Stud., 1907, 3, 523-524.

21. Liak*, P. Gruadman der WehrEhMmlehr t. Munich: 3. Reinahardt,
1918. Pp. 269-360.

22. Mcemar, Q. PsybcholoIical StatiLstic. 2d Ed. New York: Wiley,
1955.

23. Norgsa, C. T., aad Utsllar, 3. Phytiolofelcei PsichllonM. 2d ad.
New Yorkt: WmAcr-HLL, 1950. Pp. 67-74; 77-79.

24. Neff, W. S. A critical iavestigtLon *of the visual apprsehension
of wmm AM. J. i f hlol., 1936, 4", 1-42.

25. Orlansky, J. The effect of similarity and difference in aore oa
apparent visual mvewmat. Arch. Psacbol. 1. YT. no. 246.

S26. Raicbenberg, N. Apparent motion as a function of form. Un-
published N. A. Thesis, Department of Psychology, University
of Florida, 1953.

27. Rsichenberg, N. Apparent motion as a function of insctructiaa,
fori and rate of stLtulation. UnpubliLhed Ph.D. Dissrtation,
Department of Psychology, University of Florida, 1957.

28. Lubia, 3. VisueIle WahrbmuosMns Fijuren. Copenhaea:
Gyldeanalska, 1921.

29. Saucer, t. T. The effect of dark adaptation upon the perception
of apparent motion. Unpublished K. A. Tbhsis, Department of
Psychology, University of Florida, 1950.











'30. Sauctr, ft T. The effect of rate Oad eiery upon the perception
of apparent nation. Upubliftshed Ph. D. Dissertation, Departmnt
of Psychology, University of rlorida, 1954.

31. Smith. KIt. Visual apparet u menat is the abeance of muraL
interaction. A.. J. ZM l.. L948, j1. 73-78.

32. Smith., K. U. The mural canton concerned in the mdiation of
apparent mIsMat visioa. 3 Kumr. b Zclfl.. 1940, A. 443-4.

33. Stratton. G. The psychology of cha : heow to the perception
of movemet related to that of succeo ion. zRnrcl-l "o, 19LL,
f, 262-293.

34. Vernon, D.. A Further tuy VislI ?ereutioo. CmbrLdup:
University fre, 1952. Pp. 46-73; 149-153.

335. endt, P, 1. Development of as eye ca fr f e with motion
pictures. ]Z 9kL. Ur.M, Io, l-. 339.

36. VeWorthelaer, Kixperimentlle Studioen ber de Sohen voa
mlpwwgen. ZoA. I. PuvetI., 1912, a., 16L-265.

37. Wilson, 3. L The relation hips betom susuce of cortical
activity and masures of apparent atioa. UapubLiOeed I. A,
Thesis, Departmnt of PeychDlopy, Uaniversity of Florida, 1955.

38. Wilson. S. IL. ate and dark adaptatio as deteindants of appaarent
notion. Umpublished Ph D. Dissertation, Departumst of
Psycbology, 1957.
39. Woodvorth, f. S., and Sbchloaberg, . Imx;IfLkb PcholZgu.
Rev. ed. ISw York: Holt, 1954. I. 375.
















DISARIKAL Ims


The writer wea born a March 2, 19l26. at Irotoc, Ohio. He

pursued his undergraduate studies at the University of Fltorida, re-

caiving the B.A. degree June 7, 1954. s entered the Graduate SchooL

at the Ualveraity of Florida, receiving the N.A. degree ia the Collep

of Arts aad Scince, Departant .5 Psychology, June 4, 1956.

et has served as graduate asitaetC ina th Departai t of

Payehology, sa research and Laboratory assistant from Septeor, 1955,

to September, 1957, wbon be received a FeLLowuship under the Vocationaal

ehabilltatlon Traitmeaehip program. He t curmrantly serving a a

trainee la the Veteran's Administration program iu Vychology.

In 1955 be elected to th leta chapter. Alpha Kapp Dlta,,

Honorary Sociology Fraternity. In 1956 be was elected o mmberahlp

in the Florida Psychological Aasoctatioa. He as elected to associate

nemberehip is the Amrican Peychological Associatioe to 1958.












This dissertation me prepared under thb direction tof the

Chainm of the SuprviLory CoMiLtLe and ha been approved by 1ll

-mso o of the committee. It we submitted to the DUm of the ColLop

of Arts and Sciences and to the Gnradue Council and us approved as

partial fuLfLlLOnt of the requiremens for the dgre Doctor of

lhiioeophy.

January 31, 1959


Dean Colle of Arts sad sciences



Dean, Graduate ScheoL

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5
tecauM o the poculiar spatial projection la the optic chiasms, ha
fait that the require4 Interaction could not have taken place at that
level. Moreover, he Interpreted his findings as contradictlag the
usual Gestalt theory of apparent notion. The later study by Corbin
(4) nay prvida a better frane of reference for the Interpretation of
these findings than that used by Snlth hinself.
Corbin (4) presented his Os with the stiaulus lights arranged
as fronto-parallel lines at various distances, and than presented than
with stellar lines slanted at 60 iron the vertical. By so slanting
the lines, the actual retinal separation of the stiaulus lights Involved
only half the distance apart In the second as In the first presentation.
Be obtained the same tins thresholds with both types of presentations.
Thsse thresholds should have dropped markedly In the second presen
tation because of ths lessened spatial separation, if Korte's Laws hold.
Be Interprets his findings as being quite difficult to reconcile with
Wertheimer's (34) theory of isomorphism which seeas to demand an actual
physical separation of the areas of stinulatIon In the cortex that
represents the analog of the physical separation of the stteull In
space.
What does seen important In the interpretation of these findings
is that It Is not the physical separation of the areas of stimulation but
rather the perceptual separation uhich governs the 1 teens obtained.
This reinterpretation of the findings would bring them into consonance
with ths Gestolt theory. Kills (4) considers the phenomenon n function
of the entice field as aa integrated Gestalt. It Is not ths product of
say one variable in vacuo. Moreover, he would apply this theory


CHAfTXR Ill
RlfiUI
Each 0 mm presentad ell of the three grounds. The order of
presentation is shone is the Grseco-Lstin Square (Appendix A). line
flash-retea, amused in ascending and descending series, ere used to
determine the upper sad lower thresholds, optimal flesh-rete, end the
range* These four observational variables constituted the Measures of
the g'e perception of apparent Motion used in this study. The sMoant
of Bets Motion seen at each rate and for sash ground ues date mined fron
Measurements taken from the Garb rand waned- paper* tape and then converted
to time. Those Measures were entered in a table which mss used to
determine the thresholds by linear interpolation. Optimel notion was
derived from the table aa a nodal score. The range woe derived aa the
difference between the upper end lower thresholds{ it thus represents a
flash-rate range within which apparent notion nay be perceived under
these conditions. In determining the thresholds, ths 50 per cent linen
was used.
Several criteria were found necessery in screening the data.
It was considered essential that each g see notion for at least half the
tins for one rate. A second criterion was that g should be able to
report consistently. Thus, an g who exceedsd the threshold, continued
for e flash-rate above the threshold, and then sew Ism than SO per cent
notion, only to return shows the threshold, was considered not to have
22


LIST or TABUS
Tabli nag*
1. Measures of Beta Met lee According to Ground
Properties . 25
2. Consistency of Ground Effects for Lower and
Upper Fleeb*rate Thresholds, Optlael Beta,
and Benge of Beta Metioa 27
3. Analysis of Variance for Variables Modifying
Lower Flash-rate Threshold: Grounds X
Order of Presentation X Replications ...... 30
4. Analysis of Variance for Variables Modifying
Optlael Plash-rate: Grounds X Order of
Presentation X Replications 32
5. Analysis of Variance for Variables Modifying
Upper Plash-rate Threshold! Grounds X
Order of Presentation X Replications 33
6. Analysis of Variance for Variablaa Modifying
Bangs ef Motion: Grounds X Order of
Presentation X Replications 34
7. Significance of the Differences Betunen the
Means of the Measures of Beta Motion 34
iv


13
MMtiag Mural fluida la oread to cross the alternating hunda o
excitation aad quiescence la the cortea. It la anticipated, than, under
the principles of neural ananattoa, that this should require noca energy.
It nay ha expected that the range of flash-rates within which apparent
notion la seen nay ha restricted if both of these operate la conjunction.
s
This restriction should take place by raising the lower flash-rate threshold,
aad lowering the upper linen.
thirdly, horiaoatally barred grounds nay be used, furnishing the
ground against which the apparent notion is to be seen. These should
than set up in the cortex on analog of the spatial arrangsnant of the
original stiaulus. Accordingly, the bands of excitation created by the
stimulus lights of the Beta notion apparatus will he arranged parallel
to these bands of excitation and quiescence. It would be expected,
then, under the principles already stated, that these beads should fom
perceptual pathways along which the percept nay travel; thus, the per
ception of apparent notion under this condition should be facilitated.
This facilitation nay appear as an increase in the flash-rate range
within which tbs Beta-type notion nay take place. This increase in the
ranga should occur because such facilitation will tend to lower the
lower flash-rate threshold, and to raise the upper flash-rate linen.
To sunaerise these hypotheses, then, it is anticipated that
(1) the greatest range of flash-rates within which apparent notion can
be perceived will be of the non-figured ground; (2) the vertically
barred ground will inhibit to the greatest extent the perception of
apparent notion; and (3) the horiaontally barred ground will occupy an
intarnediate position between these two.


28
table. these MMum an fairly atabla with only om exception. This
exception occurs at tha optimal rata far tba non-figurad ground
corralatad with tba Os' raporta for tha horlsootal ground. From tba
otbar coafflclaata for this aaaaun, It will ba aaaa that tbay, wbila
aignifleant, an aignlleant only at a much lowar laval of confidanca
than an tba coafflclaata for tba otbar neasums. Zt would appear, than,
that thla la tba laaat atabla of tba aaaauna uaad. It ahould ba
raaaaband that thla waaaun waa cowputad frow a nodal nunbar of tba
par cant of notion aaan. It waa thua baaad upon only one aeon for
aacb 0, tba threshold values wan baaad upon three values by naans af
a linear Interpolation fren tba data as entered In a computation table.
Xt waa noted that tba Instability Inherent la using only one scon la
probably Indicative of tba source af this Inconsistency of tha 'a
report. Xt nay be concluded, then, that this inconsistency nay be an
artifact of tba wsthod of computing this naaaun. Xt nay be further
conciudad that the other naapurea an nlatively stable.
The Fearaon prodoet*moawet comistin coefficients wan further
evaluated by anana af tba | ratio* Tba formula presented la Melonar
(22) was used. These comistin coefficients nan tested against tbs
null b)fcOwsla (that than was no significant difference between tbs
obtained corn let too coefficients and sen). Xn all but tha one case
already noted, the null hypothesis was njected at the .01 level of
confidence or batter.
Four complex analyses of variance van completed for this study
(19). Xn each af these than won three fined and one randomly die*
tributad variable.


35
focan La for corralacion oca confuted to detention Cha signifcanos of
diffaraaca batanan cha ana of tha asuras of Bata notion. Tteeaa
ara prnsantad in Tabla 7. Thraa jg£ naca significant (j> < *01).
Tan ara t tha uppsr thraahold batanan tha neo-figurad and tha verti
cally barrad ground, and betunan tha non- figurad and tha horiaontally
barrad ground, Tha third ana for tha canga of tloa batea an tha
non-figurad and tha vertically barrad gcouad. Tvo other | ration ara
significant (j> <( ,05), For the Lower Lian the significant are
batanan tha varticaLly barred and tha noo-figurad ground. For tha
ranga of notion tha significant t na batanan the horiaoataUy barrad
and tha non-figurad grounds. For tha othar _t ratios, the null hypo
thesis oust ha accaptad, and it aaa concluded that these grounds ara
not a statistically significant source af variance far tha as tasted.


27
TASLg 2
C0MK8IBDCY OF CftOUHD tWBGXt FOR LOWER AMD OFFER
FLASH-BATS THRESHOLDS, OPTIMAL BATI, AMD BARBS
OF BETA MOIIOH
Measure
Ground
Vortical
Ground
Horiaootal
f t i _
Ground
Lower Plaah-Rate Thraahold
Ron-figurad
0.72**
0.00**
Vertical
a
m
0.63**
Optiaal Flash-Rate
Hon-figurad
0.01*
0.02
t
Vortical
OH
0.00*
Upper Plaah-Rata Thraahold
Roa-figurad
Vortical
0.33**
0.53**
0.50**
Ranga of Motion
Ron-figurad
Vortical
0.53**
0.53**
0 62**
Significant at tha O.Ol laval of confidanca, df 2 30.
Significant at tha 0.001 laval of confidaaca, df 2 30.


THE EFFECT OF CHANGES IN CERTAIN
DETERMINANTS OF GROUND UPON THE
PERCEPTION OF BETA MOTION
By
HERBERT CARLTON HART
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
January, 1959

ACKNOWLEDGMENTS
The writer wishes to express hie sincerest appreciation to the
Chairman of the Supervisory Comnittee, Dr. K. P. Home. He wee ee
unfailing source of inspiration and a critical person in the fomotive
stages, and gave unstintiagly of his tine, knowledge, and patience in
guiding the course of this study.
Many thanks are due the members of the Supervisory Connittee,
Drs. A. M. Barrett, J. C. Dima, W. W. Bhnsatm, t. D. Hinckley, and
H. B. Webb.
Thanks are also due the many persons who served as subjects for
this experiment.
ii

TABLE OF CORREIS
*
ti
LUI OF TABLES tv
LUI OF ILLOSIBATZOMS V
Chapear
Z. INTRODUCTION . . 1
IX. APfABATUB AND PROCEDURE U
Z1I. RESULTS 22
rr. discussion aid conclusions 37
V. SUMMARY ........ ....... 43
AF1UDXX AS
REFERENCES 46
1U

LIST or TABUS
Tabli nag*
1. Measures of Beta Met lee According to Ground
Properties . 25
2. Consistency of Ground Effects for Lower and
Upper Fleeb*rate Thresholds, Optlael Beta,
and Benge of Beta Metioa 27
3. Analysis of Variance for Variables Modifying
Lower Flash-rate Threshold: Grounds X
Order of Presentation X Replications ...... 30
4. Analysis of Variance for Variables Modifying
Optlael Plash-rate: Grounds X Order of
Presentation X Replications 32
5. Analysis of Variance for Variables Modifying
Upper Plash-rate Threshold! Grounds X
Order of Presentation X Replications 33
6. Analysis of Variance for Variablaa Modifying
Bangs ef Motion: Grounds X Order of
Presentation X Replications 34
7. Significance of the Differences Betunen the
Means of the Measures of Beta Motion 34
iv

LUX OF ILLUSTRATIONS
Figure feg
i* Block Diogroe of the Light Proel ......... 17
2. Block DUftaa of the Exporlaontel Boom
It
V

CHATTER I
XHTROOUCTIOM
The purpoM of thia study is to lavestlgste tbs offsets of
certain characteristics of flood grounds upon the perception of Beta-
type notion. In perception, figure-ground relationships here been
known end often reported; however, these noet often involve static, un-
noving perceptions (11, 2f). Barely have they keen concerned with
figure-ground effects in e dynamic field ee represented by the phi-
phenomenon (). There have been no specific Investigations of fined
variate ground effects on the perception of apparent notion of the
Beta-type.
The Beta notion is a relatively single perception which is far-
reaching in its theoretical importance. If an 0 is presented with two
fleshing lights, the flash relationship being such that ee one light,
"A", goes off, e eecond light, MB, gone on, the perception nay be that
of e single light which noves from the first position to that of the
second (34). If the relationship is continuous, i.e., ABABABAB ...
AB, the perception nay be that of e single light which noves backward
and forward between the two positions. It nay appear to nove in e two-
dimensional plane, or in e three-dimensional path. This is the Bate
phenomenon (33).
There ere e number of variables involved ee earlier experiments
have shown (A, 4, 14, 24). The flesh rate in terns of couplets cycles
1

2
per second (A M| offi A off, 1 on), tte duration of tte pause, if anp,
bttwu A and B, lateasitp of tho atlaulus light a, duration of tho
flatten, aaasuat of dark adaptation prior to tte presentation of tte
licita, diatanca betunen tte lighta, iaatructiooa to tte j, laagth of
tte praaaatatioaa, praaanca of figuvaa includad on tte faca of tte
atiaulua lighta, and tte background havo all bona shown to ba iaportant
variables <1, 2, IB, 34, 37).
Tte ralatioaabip of panno tiaa botnoaa tte ligbta, intoneitp, and
opatial aoparation ora furtter invoatigatad bp torta (It). Tte fotacl
statenant ia kaow an torta'a Lawn, although aoaa of bin findlaga tena
racantlp tean quaatloaad (6). torta found that a abort tiaa la tamal
batucan tte two oxpoauraa, a long diatanco batucan tte atiaulua ligbta,
and a low la tana it p of atiaulua ligbta ando perception of tte ptenonaoon
difficult. Ho one of thane conditlona acta in itself} ratter, there ia
an iaportant interaction betunen tte uariabloa. Corbin (4) abound in
hla aaparlaaata that a long diatanco tetween tte ligbta can ba bridged
bp a long pauaa tiaa.
There have boon a atiabar of theoriaa attempting to explain
apparent action. Aaoag tte earl lent of tbaao una tte epe-aovoaant
tbaorp which atetad that the aoveaant of tte apea and their auaculature
accounted for tte perception of tte notion. However, Guilford and
Halcn (12) abound that there uea no aigniflcant correlation betunan
tte reporta of apparent notion and tte photographic record of epe aova*
anata during tte report. Wendt (35) abound that during tte perception
of apparent notion, tte apea ware engaged la fixating objacta juat aa ia
tte perception of coal aoveaant.

3
Inner (7) proposed la 1173 retinal asura1 theory to account
for both real aad apparent motion. Zt involved the interaction betunan
elements in tbs retinae when the elements mere successively stimulated.
This interaction served to smooth into one continuous percept the stimu
lation of the series of discrete points in the retinae. However, the
finding that apparent motion took place aben one stimulus urns presented
to one eye aad another stimulus to the other eye effectively vitiated
this theory, for there could not possibly be any retinal neural inter
action under these conditions (3, 31). Wertheimer (34) proposed the
next step in a modification of laser's theory. He placed the accessary
Interaction centrally, in the cerebral cortex, rather than peripherally,
in the retinae.
There have been a number of experiments performed using only one
eye, using both eyes together, and using both eyes separately (3, 31).
These aimed at substantiating or refuting the neural interaction theories.
Xf both stimulus lights are presented binoculariy, then interaction of
the generated neural fields could take place at any point along the
visual corticopetel pathways; the retinae, the optic chiasms, the
lateral geniculate nuclei, the optic radiations, or the striate cortex
(Irodmana's area 17), or even in the mora cenote subcortical structures
(23, 32). Similarly, the presence of the stimulus lights in one eye
would rule out one-half of the peripheral neural system, but would not
rule out any of the more central structures because of the hsmidecus-
ation of the optic tract at ths level of the optic chiasma. But by
presenting one light to one eye, and another light to the other eye,
only ths central structures could be involved in the neural interaction (37).

4
Gengerelli (8) investigated the effect of heteronymous end
hewayoui stimulation of the trete cortex la ea attempt to answer
thie problem of interact loa. By heteronymous stimulation he meant
preeentlng the stimulus lights la such e meaner ee to etlmelete the
striate cortex in both hemispheres. Homonymous stimulation occurred
hen stimulation took piece la only one hemisphere. Me uead e split-
field technic hy mesas of half-silvered mirrors. Be presented different
stimuli to each eye. Underlying this tchale le the assumption of
spatial projection of areal stimulation through the optic chiasms, the
lateral geniculate bodies, the optic radiations, and the atriste cortex,
with the preservation of patterning la ell these structures (23). Under
these conditions, he found that hie Os saw the largest amount of
apparent motion under the hosunynoue condition. He ascribed hie
findings to the Interaction of neural fields taking piece la the cortex,
sad not la the subcortical structures of the visual corticopetel path
ways. However, his findings were questioned by Sslth (31).
Smith (31) presented hie Os with two lights which were mounted
on e headband. The lights were adjusted in such e meaner that the
Images formed hy the lights were on the extreme nasal borders of the
retinae. Only one light could be seen by either eye. This mode of
presentation resulted la the stimulation of t extreme borders of the
striate cortex, bordering an the calcarine fieours. This etimaletloa
thus gave the maximum possible separation of the erees of stimulation
of the cerebral cortex. Nevertheless, he obtained from hie Os good
perception of apparent motion. He Interpreted hie findings ee ruling
out neural field Interactions on both the peripheral end central levels.

5
tecauM o the poculiar spatial projection la the optic chiasms, ha
fait that the require4 Interaction could not have taken place at that
level. Moreover, he Interpreted his findings as contradictlag the
usual Gestalt theory of apparent notion. The later study by Corbin
(4) nay prvida a better frane of reference for the Interpretation of
these findings than that used by Snlth hinself.
Corbin (4) presented his Os with the stiaulus lights arranged
as fronto-parallel lines at various distances, and than presented than
with stellar lines slanted at 60 iron the vertical. By so slanting
the lines, the actual retinal separation of the stiaulus lights Involved
only half the distance apart In the second as In the first presentation.
Be obtained the same tins thresholds with both types of presentations.
Thsse thresholds should have dropped markedly In the second presen
tation because of ths lessened spatial separation, if Korte's Laws hold.
Be Interprets his findings as being quite difficult to reconcile with
Wertheimer's (34) theory of isomorphism which seeas to demand an actual
physical separation of the areas of stinulatIon In the cortex that
represents the analog of the physical separation of the stteull In
space.
What does seen important In the interpretation of these findings
is that It Is not the physical separation of the areas of stimulation but
rather the perceptual separation uhich governs the 1 teens obtained.
This reinterpretation of the findings would bring them into consonance
with ths Gestolt theory. Kills (4) considers the phenomenon n function
of the entice field as aa integrated Gestalt. It Is not ths product of
say one variable in vacuo. Moreover, he would apply this theory

I
equally to the neural finida of tha cantral nervous ijntia aa noil ao
the parcaptual fiald. Tha antira Mosaic, than, from tha axe amal
stimulus field through tba rscaptora, tha cortlcopatal nschaalsns, and
tba cortex itself, all anear into tba final perception: these together
constitute tht functional Mhola.
The effect of the ground upon the perception of flgureo con
tained within that ground haa had a long history in psychology, hut baa
been explored met extensively by the Gestalt writers (6). garly work
Included Chat of Rubin (28), Gottachaldt (10, 11), and Koffka (Id, 17),
In general, Rubin worked upon the effects in perception of the re
versible figure-ground illusions. Gottecheldt did noet of bin work
witk coaces loan t of figure la ground. These effects ware all in static
fields, however. Koffka dealt sure with the effect of ground in
dynonic fields, aa in the perception of apparent notion. We will
detail two approaches hare: that of Duncker (5) and one of Koffka'a
(Id) which deal with tbs dynonic field percepts.
Duncker'a work dealt with induced notion: the perception of
notion produced in one figure by the notion of another in the field,
end the notion produced in the figure by the notion of the field against
which it wee seen. In hie experiment, he exposed successively by neons
ef s tsehistoscope two rectangles with dots placed upon than. The dots
alone ware superimposed in successive presentations, first in one sad
then la s second rectangle. In another series of experiaeats,
neither the dote nor tho rectangles were superimposed. Hie finding*
indicated that the fixated figura nee tha norm susceptible to tba induction
ef notion, the enclosed, rather then the enclosing figure, showed the

7
inatar tendency toward induced notion. It eeene reesonable to
interpret hie findings ee dealing with figure-ground relationships.
The fixated figure can be considered to be in sharp focus, the non-
fixated figure less so. The one is seen as figure, bile the other
tends to bacons ground. His findings then indicate that the ground is
stable, but that the figure is susceptible to the induction of notion.
The ground any be considered to Com an anchor for the figure t the
figure is seen to am against a ground. If the fixated figure is the
enclosing figure, then notion is less likely to be induced. This eeene
to indicate that the enclosing figure, although fixated, is yet seen as
ground, and not as figure. However, this interpretation aaana the nost
logical one in terns of the Gestalt principle of orasnans. Bartnana
(13), while he discussed the exparlnent, does not answer this interpre
tation, nor does Duncker.
The experinant Koffka (16) perfomad wee in refutation of Linke's
(20, 21) earlier work. Linke's Of were presented with e perisphere
(a ami circle with a depreseed center, the erne pointing up) on which
was drawn a dot. In a succession of presentations, the dot was placed
in a series of intimadlate positions around the perisphere. The
perception was that of a dot rolling around in a aeniclrcle against a
fixed ground. Links interpreted his findings as being an Interpretation
of the percept by the 0 based upon his pest experiences, e.g., such as
seeing a bell roll around the inside of a bowl. Apparent ant ion,
for Links, was net a given fact, but was Inferred iron pest experience.
Koffka (16), in a neat reversal of the experinant, refuted
Linke's interpretation but confirmed his findings. Koffka presented

8
kii te with a alalia* design, but with tba a pax of tha parlaphara
pointing upward and tba ana downward. Tba perception raportad by bia
Of waa exactly tba sane aa tfaoaa ra portad by L. lake's, but, of coursa,
paat experience could not now bo coaaldarad a baala for tba parcapt.
Banca, Koffka coaaldarad apparant notion a glwan, not a laamad, fact.
Koffka want furtbar, bowawar. 8a presentad bis with tba dota la
exactly tba sana poaitloa aa bafora, but without tba parlaphara. Tbla
tine tha percept was of a aarlaa of dota junplug about; they no longer
rolled enoethly fren one position to tba next. Ha interpretad bis
findings aa nsanlag perception la a function of tba entire field, and
not af one part of tha field without consideration of tba reminder.
These experlnsnts show without question that theca era definite
effects upon tba perception of apparant notion of tba changes in tba
ground against which tba figure la seen. Tbla baa, af course, bean
known a long tine la tba studies of perception of static fields. Barly
investigations noted that sons figure properties in fans perception of
apparently mvlag objects ware influential la perception. leicheaberg's
study (27) Indicates that In tha duration of perceived notion significant
dlffaroncea between all combinations of figure patterns war* not ob
tained. neither la term of nasa tina for perceived notion nor in
total tins of perceived notion of two lighted figures la notion was fora
s significant variable. In an analysis of naan tins for perception of
one lighted figure in notion, e.g., optIns1 nvenset, fora was signifi
cant In tba £ test. Aa F test for analysis of variance of total tine
of perceived notion was not significant. Thus, figura Is laportaat la
sons nsasurensats of apparent notion but not in all.

9
It the figures are different la tom or la color, this differ
ence any bacons ea iaportant variable la the percept loa of apparent
aotioa. Orlanaky (29) explored these variables. He tom that If
the stloulue lights ere eboea la the fore of too arrows pointing la the
sene direction, aotioa Is easily seen by aoet Of; It is quite cea
palling, end Is very realistic, but if one arrow palate to the right
end the other to the left, It becoaes auch aere difficult to perceive
apparent aotioa, and It is easily lost. More tlae oust be allowed
between flashes (l.e., by increasing tbs pause tlae er by decreasing
tbs flesh rate) if apparent aotioa Is to be seen. Ivea so, a coa-
side reble aunber of Of cannot obtain good aotioa under these conditions.
Kills (t) explains this phsnonsnon under the headings of pteoasns end
of coanon destiny. Belcheaberg (26, 27) carried out on additional
study la this erne. His findings la general confined those of
Orloasky although he used very different stlaulus figures.
The phsooasnoa of epperene notion Is not Halted entirely to
the use of alternate lighted areas, although this node of presentation
has been the aost manna la the pest (33). brown (3) found that e
similar phenoaanon was obtained In the perception of reel aotioa under
certain conditions. brown used a continuous strip of paper to which
black rectangles bed been applied, and varied the speed of rectangles
aovlag pest e slot. A aesk concealed the remainder of the strip.
The g observed the no vacant. When the paper wee aovlag at a high rate
of speed past the slot, the rectangles were perceived as a continuous
bend of gray. At low spesds, the rectangles were reported as saving

10
la ti direction of t)lr coal notion. At crtala In to rood loto o poo do,
>
tho te reportad the rectangles aovlng la a direction oppoolta to the
direction of their objective ement, Krooa Interpreted hie findings
correctly os a true example of apparent sot ion.
The purpose of the preeeat etudy le to lnveetlgote the effecte
of crtela determinants of ground upon the perception of Beta notion.
It has been shown la a number of experiments that ground has an
important effect on the percept. Thera era a number of determinants
of ground and figure relationships detailed by the Gestalt writers.
Among the principles determining the percept of figure are those of
clearness: the figure Is more sharply defined than Is the ground.
The ground Is the lose distinct of the too. and tends to he Ignored la
reports of the percept. The figure Is morn Interesting or lively then
the ground, and seems to stand out from the ground; the ground seems
to continue behind and to he hidden by the figure. These principles
are grouped under the general heading of ernsnana: the moenlagfulness
of the parts of the percept (4, Id).
A second principle Is that of comean destiny: the figures and
the ground seem to share an end comnon to both. Thus, if a vertically
barred ground Is presented against which Beta motion Is to be seen,
these vertical bars can be thought to shore a rnnman destiny with the
percept of apparent motion (6, 14). Under the principle of prsgnans.
such e ground should form a barrier to the continued perception of
apparent notion because it forces the apparently mowing stimulus lights
to cross successively a aeries of dark and light stripes. Conversely,
a ground which contains stripes of light sad dark arranged horiaoatally

u
o that tha tripa* lia paralia1 to tha anticipatad path of apparant
notion should fcil itata tha parca pt by Coming pathways. A ini lar
parcapt aaana to have occurred in Koffka'a (16) experlsamt.
A third principia with which this experiaent daala la the
Oaatalt principia of laonorphiaat tha rapraaantation in neural alaaanta
of tha aanaory etiaulus with praaarvatlon of tha GastaIt of that atiaulus
field (6, 16). Thus, translating tha previously presented nodels into
lsonorphlc tarns, one would expect that tha vertically barrad gratad
would stlaulate selectively neural alaaanta, and that there would ha
a preservation of its Com in tha patterning of the atiaulation. For
axaapla, such a ground as the vertically barred one discussed previously,
would sat up alternating bands of excitation and quiescence in tha
; it
striata eortsx in an exact analog of tha original at inulus. Such a
continuing stinulus as la presented by Bata nation would produce an
interacting neural field ouch that a continuous band of excitation
would cross and recross the cerebral cortex in exact neural represen
tation of the percept of the notion as reported by the 0.
Zf the interaction of neural fields set up by the stinulus lights
is necessary for the percept of apparent notion to take place as is
denaaded by tha Gestalt theory, then it scene likely under the principles
Just outlined that certain types of cortical fields should act to in
hibit or to facilitate the perception of apparent notion. In line
with a Gestalt theory of apparent notion, bands ef quirsoeete ard ex
citation should be set up in the cortex (strictly speaking, in tha
neurons asking up the cortex) by that ground corresponding to the

12
arranganent presented by Chat ground la visual apees, and thasa hypo*
thatleal banda ahould hava an important aCfact on tha pareaptlon of
apparant notion (2, 23).
k position for tha derivation of throa hypothaaaa baa boas
astabllahad. Tha next atap ia to daoign an experiment to taat than.
First, it nay ba antieipatad that tha non-figurad, i.a., plain, ground
ill prvida tha laaat interference with apparent notion. It will do
this because, under tha principle of lsoamrphisn, it ill consist only
of uniformly excited neurons. Because it poses no barriers to the
pareaptlon of apparent motion, it is anticipated that it will provide
tha largest flash-rate range of apparent motion. If tha upper flash-
rate threshold for apparent motion is measured, it should follow that
this value is increased: the j is able to perceive apparant motion at
a higher flash-rate before it breaks down. It should also follow that
the £ could perceive apparent motion at a lower flash-rate: tha lower
flash rate Ilmen should be decreased. The net result should be an
increase la the tangs of flash-ratas within which apparent motion may
be perceived.
Secondly, if a vertically barred ground against which apparent
motion is to be seen is used, it ia anticipated that such a ground
should form a barrier to the perception of apparant motion. In tha
cortex, under tha principle of isomorphism, it is expected that alter
nating bands of excitation and quiescence corresponding to the alternating
bands of dark and light on tha ground would be set up. Since a horl-
sontally moving light is produced in the apparent notion apparatus,
this naans that the band of excitation set up by such e percept ia

13
MMtiag Mural fluida la oread to cross the alternating hunda o
excitation aad quiescence la the cortea. It la anticipated, than, under
the principles of neural ananattoa, that this should require noca energy.
It nay ha expected that the range of flash-rates within which apparent
notion la seen nay ha restricted if both of these operate la conjunction.
s
This restriction should take place by raising the lower flash-rate threshold,
aad lowering the upper linen.
thirdly, horiaoatally barred grounds nay be used, furnishing the
ground against which the apparent notion is to be seen. These should
than set up in the cortex on analog of the spatial arrangsnant of the
original stiaulus. Accordingly, the bands of excitation created by the
stimulus lights of the Beta notion apparatus will he arranged parallel
to these bands of excitation and quiescence. It would be expected,
then, under the principles already stated, that these beads should fom
perceptual pathways along which the percept nay travel; thus, the per
ception of apparent notion under this condition should be facilitated.
This facilitation nay appear as an increase in the flash-rate range
within which tbs Beta-type notion nay take place. This increase in the
ranga should occur because such facilitation will tend to lower the
lower flash-rate threshold, and to raise the upper flash-rate linen.
To sunaerise these hypotheses, then, it is anticipated that
(1) the greatest range of flash-rates within which apparent notion can
be perceived will be of the non-figured ground; (2) the vertically
barred ground will inhibit to the greatest extent the perception of
apparent notion; and (3) the horiaontally barred ground will occupy an
intarnediate position between these two.

CHAPTER II
AmiATOS km PROCEDURE
toBMESHI
Tte apparatus dividas into tha followingj the alactcoalc switch,
tbs stlaulus lights sad grounds, and tha recording eguipaent.
IMftJSftteB maiHg -ThU part of tha apparatus consisted of
an electronic switch controlling two gylvenia Ell 1301 electronic glow
tubes, tha stlaulus light sources. The switch used was described by
Saucer (30). It la a wide-hand, high-gain pentode r-f amplifier in a

multivibrator circuit. Tha gating signals produced are aguare, having
a negligible rise and decay tine. Cathode coupling is used to tha
K1130S tubes to preserve this wave-fora. The circuit la stable to 15
kilocycles (kc); it la no really operated wall within thia sargia.
Several flash-rata rangas are provided in tha control switch, giving
rates free 0.2 flashes per second (f/a) to 30.5 f/a.
Tha second portion of tha apparatus included tha stlaulus
lights, tha equlpaeat used to support and llluaiaate tha grounds, tha
Ions associated with tha 111300 tubes, and the diffusing screens. Tha
Sylvsala 111308 glow tubes provide a sharp response up to tha ioni
sation value of the tubs which la approximately 15 kc. The actual
decay and risa tina of tha light stlaulus la on tha order of 2 to 3 nieto*
sac. The light output of the tube varies linearly aa tha plate current.
1*

15
t approslaataiy 55 uiUaaparaa (aa.) lt yields approslaataiy a daylight
apoctrua. As tbs plata current la decreased, the omitted light shifts
toward tha long wave-length and of tha spectrum, i.a., toward tha rada.
Viriag af tha tuba baeoaaa erratic below 5 aa. plate currant. Tha
brightness of tha two tubas was equated pathologically, rather than
by watching plate currants. It was found that slight differences be*
tween tubas in light output at identical plate currents preclude tha
use of plate current asaauresents alone being used to equate tha lights.
Fleta currants in this study ware bald between 12 and 15 aa. la
aounting tha &1130B tubas in tha light panel, a lens systaa was used
to provide parallel aalssion of tha light rays on tha diffusing screen.
An aperture was designed to Halt tha visual angle subtended by tha
stiauius lights to 5 at one aster (a.) froa tha 0; however, due to
diffusion through tha ground glass screen, tha angle was approslaataiy
6, as asasured at tha outer Halt of tha disc of light.
Three grounds ware constructed for use in this study. One was
plain, i.a., non-figurad. A second consisted of parallel, opaque and
translucent 7 an. stripes in a horiaontal arrangaaent alternately
placed. The third was constructed with stripes of ease width alter*
acting opaque and translucent vertical hands. These grounds were
constructed by gluing 7 aa. stripe of black construction paper spaced
at 7 an. te Talos tracing paper. The black stripes ware quite opaque,
very sharp, and of equal width throughout their length. The Talos
tracing paper provided a gralaicas, translucent area through which wee
projected the light froa tha 11130B tubes, and the light used to

l
illuminate tbt ground*. The** ground* unen aclosed In a heavy card
board fraa*. th* ground* wens all 26.1 en. by 31.9 ca. subtending
10.2 vortical and 13.0 boriaontal viaual angla* at on* au Croat tb* 0.
Tba*a ground* oro mounted in a alid* in tb* front of a light
tight box vhieh contained, in addition to th* K113CB tuba* and tboir
laa* ays tan* and aportar**, a 26.8 on. by 31.9 cm. ground-glass dif
fusing croon and too 13 uatt incandescent bulba, rod in color and
tubular in shop*, which wars noun tod vertically on each aid* of th*
croan. The bright**** of th* ground illumination an* controlled by
varying tb* voltage across the tubular lamp* by asan* of a Variac trans
formar. The vo1tag* an* maintained at 12 volts (v.) throughout the study.
Th* illumination an* rad for the ground* in ord*r to maintain tha O'*
dash adaptation at a atabla level (29 39).
Tb* antis* light penal, tha ground support, and tha O'* chin
rust aura inclosed in a light-tight tunnel mounted on an optical banch.
Tb* dUtanca from tb* light panel to tha £' chin vast ana maintained
at orna m. A block diagram of th* light panel is shown in Fig. 1.
Tha optical bench, th* £' booth, and tha aatlro room war* all
paintaw flat black to absorb light. Considsrabla car* an* taken to
prevent light leakage from tha £' boothnecessarily illuminated in
the course of th* experimentor from external source*. Leakage would
naturally vary tha adaptation level of th* £ during the course of th*
experiment. It should ba noted, however, that the naan duration of
notion perceived during parlad* longer than 4 min. of dark adaptation
is relatively constant (3§) and mean duration is not significantly
changed by change* in illumination within th* rang* need (30). 4

17
-

-- T~y 7 V -
-- v_y =
-
A R1130B Stimulus Light
B Ground (Horizontally Barred
Ground Illustrated)
C Light Panel Support
D Optic Bench
E Chin Rest
Fig. 1.--Block Diagram of the Light Panel
OB >

18
block diagram of the cooa and apparatus is shorn in Pig. 2.
Sf,Pratue.~A telegraphic key was mounted conveniently
for the 0 within the optical bench tunnel and connected through a
suitable power supply to the recording relay of a Garb rand waxed-paper*
tape signal recorder. The g placed dietiactlve signals on the tape at
the beginning aed id of each trial. These were used to locate each
trial. Oaring a trial, 0 pressed the key down aa long as ha wee
perceiving Beta notion. Since the paper tape wee fed through the
recorder at a constant speed, distance along the tape wee translated
to tine and the aeount of apparent not ion reported under each condition
issss&m
Observers consisted of 36 young adults of college age who showed
no obvious signs of brain dnaegt.
lack 0 was given instruction and several orientation trials
prior to the beginning of the axperleent proper. During this period
oe ground or rate ueed in the experiment wee preseated to the 0. it
wee found that neat Os had considerable difficulty in differentiating
Bote notion free the shadow-notion phenomenon at the higher flash-ratee*
Conoide reble training wee foued necessary for the g to render an
accurate, reliable report of his perceptions. During these orientation
trials, the Os were instructed in the use of the telegraph key con
trolling the Cerbrand recorder.
Bach g was given four min. of dark adaptation prior to the
beginning of the experiment proper.

19
Legend: A Electronic Control Switch
B Gerbrand Paper Tape Recorder
C E's Position
D Light Tight Equipment Booth
E Stimulus Light Panel
F Gerbrand Recorder Control Key
G Optic Bench
H Chin Rest
I O's Position
Fig. 2.--Block Diagram of the Experimental Room

20
Of necessity, the instructions wn miad in content for Mch
g, for hm wn oro miliar than otilara with tba phenomenon. In 11
casas, tha asaantial Aullaban ara conatant. Moca aecusaca multa
aaca obtained by equalising tba practica affacta among j{, Each j aaa
alionad to become thoroughly familiar with tha charactariatica of Bata
motion at each flash-rate. Although tha content of tha iaatructiona
aaa variad with thaaa 0a, tha iaatructiona aaca dealgned to iaatill a
aiailar Kinatalluna la each g. Following thia period tha aapacimoatal
observation began.
Of ware assigned to a Oraaco-Latin Square in seriatim order (19).
(Sea Appendix A.) Although Gilbert (9) had shown practice may ha of
soma importance in tha perception of apparent motion a more meant
study by fteichenberg (27) indicated that mean duration of notion ana
not significantly different during three successiva practica periods.
However, the use of thia type of experimental design provides a control
of thia variable, since each ground was presented in each ordered position
an equal number of tinea.
Tha uaa of this experimental design also provided tha schedule
for tha presentation of all grounds to tha Of. Tha presentation of
each ground then was of a descending and ascending aeries of nine flash
rates. These rates warn 0.4, 1.5, 2.5, 3.5, 4.5, 5.5, 4.5, 7.5, and
8.5 f/a. Tha uaa of counterbalanced series was designed to preclude
any systematic error on the pert of the 0 due to anticipation or
perseveration (39). All gg warn given thane aeries for each ground.
Thus, g observed n total of 18 periods for each ground, or a total of 54

21
tins* for the three grounds.
During nek trial, cha 0 n instructed to hold the telegraphic
key down during Che tine he was perceiving Beta notloa, and Co release
. < t .
it bes Che perception use of Cvo lights fleshing, one fined light on
with the other off la cycle, or the shadow notion pheaonsaon. The use
of the key la this asonar placed a distinctive record of Beta ootloa
upon the Gerbrand tapa* Since the tape waa driven at a constant speed,
1 SEff * 1
e staple transfonation converts distance along tha tape to e tloa
aoasureaeat. Each olnute trial of motion la then converted to a per
cent tine by the equation:
H = (100)
la which t£ la tha aaount of apparent notion each subject perceived
during a trial, da, la tha distases along the tape during which ha
held the key down (waa perceiving ootloa), and D la the total distance
along tha Upa of each trial (tloa). The product la expressed as s
percentage of tha elan In which apparent notion was perceived.

CHAfTXR Ill
RlfiUI
Each 0 mm presentad ell of the three grounds. The order of
presentation is shone is the Grseco-Lstin Square (Appendix A). line
flash-retea, amused in ascending and descending series, ere used to
determine the upper sad lower thresholds, optimal flesh-rete, end the
range* These four observational variables constituted the Measures of
the g'e perception of apparent Motion used in this study. The sMoant
of Bets Motion seen at each rate and for sash ground ues date mined fron
Measurements taken from the Garb rand waned- paper* tape and then converted
to time. Those Measures were entered in a table which mss used to
determine the thresholds by linear interpolation. Optimel notion was
derived from the table aa a nodal score. The range woe derived aa the
difference between the upper end lower thresholds{ it thus represents a
flash-rate range within which apparent notion nay be perceived under
these conditions. In determining the thresholds, ths 50 per cent linen
was used.
Several criteria were found necessery in screening the data.
It was considered essential that each g see notion for at least half the
tins for one rate. A second criterion was that g should be able to
report consistently. Thus, an g who exceedsd the threshold, continued
for e flash-rate above the threshold, and then sew Ism than SO per cent
notion, only to return shows the threshold, was considered not to have
22

23
followed the directions, and eea eliminated fren the study. For each
0 lost from tbs study, s replacement 0 eea completed. The criteria
for tbs replscsesnt 0 were tbs sees as for tbs original 0, and tbs ase
g ees placed in tbs sans call of the Graeco-Latin Square.
Tbe upper aad loser flash-rate thresholds, optleal flash-rate,
and the rungs eitbin which Bata notion is seen constituted the asasurca
usad la this study. Tbs lower flash-rata threshold for Bata notion is
deflnsd as that rata bsloe which the g reports lass then 50 per cent
apparent notion. Below threshold, psychologically, the percept breaks
down into two lights which are alternately illuminated. Similarly, tbs
upper flash-rate threshold nay he defined as that rata shows which Beta
notion is not Man. For this study, "not seen" is defined as a report
of Bata notion for less than half the tins in any one trial. Again, at
the threshold the typical Bata notion percept is replaced by an entirely
different one; in this case, an 0 reports seeing two lights which are
siaultaaaously oe and flickering.
Optinal flash-rate is defined as that rata which produces the
greatest reported amount of Beta notion, expressed as a percentage of
the total. Thus, it is a rate at which tbe notion is seen nost con
tinuously by the g, and in which the notion nost nearly approaches the
percept of real notion.
The statistical analysis of the date included the computation
of the neena for all the groups for the three grounds, the standard
deviations of tbs distributions, tbs standard errors of tbs titans.
Fearaoa product-aoaaat correlation coefficients, g ratina baaed on the
correlation coefficients, end four complex analyses of variance (If, 22).

24
Tbs Mans wan confutad according to Cha standard fornula given
in McBsnar (22) and an reportad in tabla 1 fot Cha lanar flash-race
threshold, cha naan rata my be interpretad at that value below which
Bata notion la not seen. Thus, for Che non-figured ground, Che value
la 1*71 f/a. The value of cha lower linaa for cha vertically barred
ground is 1.77 f/a, and for Che horiawa tally barred ground, 1.75 f/a.
The upper threshold's wean value way be Interpreted as being that value
above which Bate notion la net sees. For Che non-figured ground, chin
value la 5.24 C/e, while for the horlaontally barred ground it la 4.68 f/a
end for the vertically bamd ground it la 4.62 f/a.
The opt Inal rate bee been defined ee the rate at which the 0
sew the greatest per cent tine of apparent notion, using the nodal value.
For the non-figured ground, this was 3.21 f/e. For cha horlaontally
hatred ground, the value wee 3.10 f/e, while for Che vertically barred
ground it wee 2.63 f/e. It wee at these values that note Og aaw the
largest anount of apparent notion.
The range, the difference be twees the upper end lower llama,
sumarias* aa a singla value the range of rates in this study at which
Beta natos wee asen. These ranges, aleo reported in Table 1, for the
non-figured ground was 3.55 f/a, for the vertically barred ground wee
2.85 f/e, dille that for tha horlaontally barred ground was 2.93 f/s.
W was desired to obtain eons satnate of the diapersion around
these values. To evslusts this, tbs standard errors ef the naans wars
confuted (19, 22). These give en satnate of values within rhleh, at
a stated fiducial liadt, the true neon of the universe of neena fren
which these obtained naans ware drawn. Setting these fiducial Units

25
TABLE 1
MEASURES Of BETA HOT IOS ACCORDING TO GROUND PROPERTIES

X
OoDtr Flaah-Rata Threshold
Hon-figurad Ground
36
5.26
1.0?
0.18
Siciaottttl
36
4.68
1.44
0.24
Vortical
36
4.62
1.46
0.24
Boa-figurad Ground
36
3.21
0.86
0.14
Horiaontal
36
3.10
1.00
0.17
Vortical
36
2.§3
0.80
0.13
Non-figurad Ground
36
1.71
0.70
0.12
Horizontal
36
1.75
0.60
0.10
Vertical
36
1.77
0.66
0.11
iMLS&HSitt
Boa-figurad Ground
36
3.55
1.36
0.23
Boriaoatal
36
2.93
1.67
0.28
Vortical
36
2.85
1.62
0.27

26
at J 1(5, U my be stated that the true mao rate for the upper
threshold of the we*fipind ground me 5.26 f/s, 0.18 f/e. The
lower threshold use 1.71 f/e, i 0.12 f/e, and the man optimal rate me
5.21 f/e, t 0.14 f/e. The range ot rates within which epparent motion
is seen wee 5.55 f/e, 2 0.23 f/s. Similar etatemte my he mde for
the mm rates for upper thresholds, lower thresholds, optiml rates,
sad the range of rates within which apparent wot loa is seen for the
It.' -* 1 1 1 '
other grounds.
The s tends rd do wist ions of the distributions for the serious
grounds and mesures of lets notion were confuted according to the
standard net hod given in Melonar (22). These values are suamrlsed in
Table 1. Thus, for the upper threshold of the non-figured ground, the
mm me 5.26 f/e, l 1.07 f/e. Sinilar Interpretations held for the
other values and for the various grounds.
ns number of & entering into them confutations wee, in all
conditions, 36.
> : . V . /Mm
Pearson product meant correlation coefficients between pairs of
mesuras ware confuted according to Mclsmr'e (22) nodal and are
reported in Table 2. Them my be interpretad as mesuras of the eon*
eistency with which the & reported fren one mature to another for the
various grounds. They are in a seam e manure of the stability of
the naaaures them si ves, if it can he assumd that the Jg| were consistent
in their reports. Presumably, a perfectly stable mesure, coefficient
*, i /
of 1.00, should yield the earn performance value irrespective of the
conditions under which it operates. Any inconsistency then would be e
divergence toward aero from this correlation. As my be seen from the

27
TASLg 2
C0MK8IBDCY OF CftOUHD tWBGXt FOR LOWER AMD OFFER
FLASH-BATS THRESHOLDS, OPTIMAL BATI, AMD BARBS
OF BETA MOIIOH
Measure
Ground
Vortical
Ground
Horiaootal
f t i _
Ground
Lower Plaah-Rate Thraahold
Ron-figurad
0.72**
0.00**
Vertical
a
m
0.63**
Optiaal Flash-Rate
Hon-figurad
0.01*
0.02
t
Vortical
OH
0.00*
Upper Plaah-Rata Thraahold
Roa-figurad
Vortical
0.33**
0.53**
0.50**
Ranga of Motion
Ron-figurad
Vortical
0.53**
0.53**
0 62**
Significant at tha O.Ol laval of confidanca, df 2 30.
Significant at tha 0.001 laval of confidaaca, df 2 30.

28
table. these MMum an fairly atabla with only om exception. This
exception occurs at tha optimal rata far tba non-figurad ground
corralatad with tba Os' raporta for tha horlsootal ground. From tba
otbar coafflclaata for this aaaaun, It will ba aaaa that tbay, wbila
aignifleant, an aignlleant only at a much lowar laval of confidanca
than an tba coafflclaata for tba otbar neasums. Zt would appear, than,
that thla la tba laaat atabla of tba aaaauna uaad. It ahould ba
raaaaband that thla waaaun waa cowputad frow a nodal nunbar of tba
par cant of notion aaan. It waa thua baaad upon only one aeon for
aacb 0, tba threshold values wan baaad upon three values by naans af
a linear Interpolation fren tba data as entered In a computation table.
Xt waa noted that tba Instability Inherent la using only one scon la
probably Indicative of tba source af this Inconsistency of tha 'a
report. Xt nay be concluded, then, that this inconsistency nay be an
artifact of tba wsthod of computing this naaaun. Xt nay be further
conciudad that the other naapurea an nlatively stable.
The Fearaon prodoet*moawet comistin coefficients wan further
evaluated by anana af tba | ratio* Tba formula presented la Melonar
(22) was used. These comistin coefficients nan tested against tbs
null b)fcOwsla (that than was no significant difference between tbs
obtained corn let too coefficients and sen). Xn all but tha one case
already noted, the null hypothesis was njected at the .01 level of
confidence or batter.
Four complex analyses of variance van completed for this study
(19). Xn each af these than won three fined and one randomly die*
tributad variable.

29
variance of Che muuim. According to the wyriuntal design um4,
the significance of the offacts could bo evaluated for throo sources:
tbs grounds, tbs order of presentation, sod tbs double interaction of
tbs grounds sad order of presentation* The assures, loser three bold,
upper tbreeheld, optinsl rats, and range of rates vithin which Beta
notion was seen, wars all designated as dependent variables; each
assure provided s separate analysis of variance. Ground end order
of presentation, two of the three dInanetons, ware fined variables*
The third variate waa a ran don variable, replication* This type of
design peralte the evaluation of the grounds, of the order of pre
sentation of the grounds (practice), and ef the lateaction of these
two* Evaluation of individual differences is aot obtainable. it was
assumed that individual differences would be readonly distributed and
would there fora aot neks an important contribution to tbs variance fa
this design* Since theca waa only one individual assigned to each call
under this arparlaaatal design, within call variases was acre.
The first of these analyses, that of tbs lower threshold by
grounds by order of presentation by replications, is presentad in Table 3*
It is evident that there wars as statistically significant sources of
variance between tbs variables* It nay be concluded that ground was
not s significant variable in tbs determination of Bote notion for the
assures used at the loner threshold*
Xt should else be noted that there wars ns statistically signi
ficant practice effects (order sf presentation). The control of
practice effects by assignment of Os in a seriatim arder to a Graeco-
Latin Square waa affective.

30
TABU 3
ANALYSIS Of VAR1AUCX FOR VAAIABLSS MODIFY UK LOUSE
FLASH"RATS THRESHOLD: GROUNDS X ORDER Of
RE MORAY IDE X REPLICATIONS
Soutea
so
df
Z
ratio
1
X
Grounds (6)
0.07
2
0.04
"6'SR
.36
*
Ordor of Prsooatatlon (0)
1.54
2
0.77
aso/asgt
60
so
Replications (E)
6.30
11
0.57
so
s>
so
G X 0
0.37
4
0.09
*cc'-*oo*
60
m
X ft
2.47
22
0.11
so
m
*
0 X ft
28.35
22
1.29
4*
m
-
G X 0 X ft
6.78
44
0.15
m
so
49
Vitkin Calls
0.00
0
m
m
m
SO
Total
45.88 107

31
tha affects of order of pceooatatloa sad of tho ground upon tbs
nssuranant of optlnnl flesh-cats of apparent satioo on presented in
Tsblo 4. It soy bo soon that aoao of tbo variables approached statisti
cal significance. Iban foco, neither order of proseo tat ioa nor grand
was a significant source of variation ia the dotamiaatioo of this
Measure of Beta-typo of apparent Motion,
Tbo third analysis of variance is presented ia table 5, The
fined variables More order of presentation end ground, topi lest ions
fecned a randomly distributed variable. The upper flash-rote threshold
of Bate notion nee the dependent variable. As nay be seen fren the
table, the grounds vara significant source of variance upon the Beta
notion at its upper threshold (| ^ .01). It nay be concluded that the
grounds vera e significant detemiaaat of this Measure. Again the
order of presentation (practice effect) use not e significant source of
varanos, nor vers the interactions. The grounds alee fern the ns jar
source of variance.
The last analysis of varanos on the range of cutes within which
Beta notion wee seen ia presented ia Table A. Of the sources of vari
ance ia this Measure of Befe notion only the grounds ware statistically
significant (f < 0.0B5). It should again be noted that there was no
statistically significant variation attributable to the order of
presentation of the grounds. Her was the interaction of the ground and
order ef presentation statistically significant. Fran this it van
concluded that the practice effects were effectively controlled ia this
erperlnantel design*
A aeries of ratios, corrected according to Mcflnaer'a (22)

32
TABLE 4
ANALYSIS OF VAE1AJCB FO& VARIABLES MODIFYING
OPTIMAL PLASH-RATS: GROUNDS X ORDER OF
PRESENTATION X REPLICATIONS
Source
M
4f
-
l
ratio
X
1
Grounds (6)
1*40
2
0.70
1.21
m
Ordnr of fnnaUtion
<0)
0.04
2
0.03
V"*
0.02
m
lafUcatim
U.SO
11
1.07
m
m
m
G X 0
i.n
4
0.44
-gorgor
0.81
m
6 X R
12.71
22
0.58
*
m
m
0 X X
35.80
22
1.43
8

m
G X 0 X X
33.54
44
0.54
m
m

Within Calls
0.00
0
an
m
m

Total
87,08
107
m

m
on

33
TABU 3
ANALYSIS Of VARIANCE FOR VARXABUS MODIFYING
UTTER FLASH-RATE THRESHOLD: GROONOS X
ORDER OF FRESSNEATION X REPLICATIONS
Ground* (G)
8.90
2
4.43
-c'-e*
5.84
Order of Presentation (0)
0.00
2
0.40
V^OR
0.10
Replications (R)
43.90
11
4.17
4
G X 0
4.14
4
1.04
W*^Q0R
1.17
G X R
14.41
22
0.74
m
m
0 X R
7.32
22
3.97
m
m
6 X 0 X R
39.04
44
0.89
m
m
Within Call*
0.00
0
m
m
m
Total
202.73 107

34
TABLE 6
ANALISIS OP VARIANCE VOS VARIABLES M09Z7Y1SS SAKE Of MOT IDS:
GROUNDS X OROSE OF PRESENTATION X RSILICATXD8S
Sou vet
se
it
-
l
ratio
l
1
\
Ground (G)
11.07
2
5.54
5.45
0.025
Order of Presentation (O) 1.37
2
0.48
**0/0E
0,11
40
Replications (R)
30.10
11
4.55
#
m
40
G X 0
4.92
4
1.23
^gor
1.05
m
OSS
21.51
22
0.98
OS

m
0 X R
132.15
22
6.01
4
m
m
G X 0 X R
51.49
44
1.17
m
m
m
Within Calls
0.00
0
4
m
m
m
Total
272.41
107
m
Mi
a
m

35
focan La for corralacion oca confuted to detention Cha signifcanos of
diffaraaca batanan cha ana of tha asuras of Bata notion. Tteeaa
ara prnsantad in Tabla 7. Thraa jg£ naca significant (j> < *01).
Tan ara t tha uppsr thraahold batanan tha neo-figurad and tha verti
cally barrad ground, and betunan tha non- figurad and tha horiaontally
barrad ground, Tha third ana for tha canga of tloa batea an tha
non-figurad and tha vertically barrad gcouad. Tvo other | ration ara
significant (j> <( ,05), For the Lower Lian the significant are
batanan tha varticaLly barred and tha noo-figurad ground. For tha
ranga of notion tha significant t na batanan the horiaoataUy barrad
and tha non-figurad grounds. For tha othar _t ratios, the null hypo
thesis oust ha accaptad, and it aaa concluded that these grounds ara
not a statistically significant source af variance far tha as tasted.

TABLE 7
SKX1FXCASCI OF TIB DIFFKIMCKS BKTWKIB TIB HUBS OF
TIB MEASURES OF BITA MOTXOR
Ground
Vertical
Ground
Horiaontal
Ground
. r j *i i'i y,
Loner Flast-rate Threshold
Mon-figured
2.14**
1.33
Vertical
*
0.71
Optlasl Flash-rate
Hoa-figured
1.87
0.50
Vertical
m
1.08
Upper Flash-rate Threshold
Son-figured
3.02*
2.78*
Vertical
m
0.26
Benge of Motion
Mm-figured
3.02*
2.48**
Vertical
0.46
Significant it the 0.01 lml of confidence, df Z 36.
Significant at Cbe 0.05 level of confidence, df 3 36.

CHAPTER XV
DISCUSSION A CONCLUSIONS
The ovsr-aii effect of chance la gEwnd for the upptr threshold
see significant statistically. This say he interpreted as that the
grounds did chsngs one Halt ef Beta notion. The differences hotos so
the non*figured and the borisontally barred, and the non-figured and
the vertically barred grounds, were significant. It oes found that
ths assn flash-rate for the non-figured ground oes 5.26 f/s, ohlle the
horlaoetal sad vertical grounds vote 4.68 f/s and 4.62 f/s respectively.
In asintaiaing notion perception a higher cate of action one tolerated
by ths £ for the plain la conparlsoa with the figured grounds. These
differences were statistically significant. The finding is consonant
with the hypothesis that acre action say be obtained free the non-
figured then iron ths figured grounds. The hypothesis that there would
be a differential perception of Beta notion for the horlaoetally barred
as coopered with ths vertically barred grounds oes rejected.
The other dependent variable for which ground was significant
ass mags. Tbs mage one aodifled as inly by the elevation of rate in
the upper Unit. Them warn no statistically significant differences
betwain the aeons of ths aoaeures for the grounds at the lower threehold
nor in the opt Iasi flash-rate. Them oem no statistically significant
differences between the horinontally barred and the vertically barred
27

3a
Another finding of iaportaac* mm Che consistency of |Wttd
effects for the Measures of Koto Motion. Tbs Pearson product Monsut
correlation coefficients were significant. Per several Measures,
except for certain ground effects on optinal rate, the obtained || he tesen
the non figured and vertically barred ground, and be tunea the eettieallp
and herlseatally barred grounds ewe significant beyond the 1 per cant
level of confidence. Only the correlation bateesn the non*figured and
the horieootally herrad ground* for optinal flash-rate mm not signifi
cant statistically. Moreover, the highest £ mm obtained at the lover
threshold. Xt any he interpreted as indicating that the Os mot* soot con
sistent at the lover threshold. These Os Mere not consistent st the
optianl flash-rats as*sure.
Xt uould sppnar, then, on the basis of thoM resulta, that a
flash-rata uuat have s certain Mialreea to he perceived aa appnrest
notion under the p*roasters that heve been used in thin study. The
very high consistency ef the j'e report et the lover threshold anpha-
eised (for nest Of) the constant property of this nUlaunu These
grounds have no inportant effect oe the loner threshold. On title heels,
it sesos aost reasonable that one should leek for s physiological rather
than a perceptual explanation to understand this portion of the
pheoonenon (1).
la constructing a physiological nodal to account for thin port
of the findings, aa faypothMis of o sonnet ion ef neural iapulaoa taking
placa in the cerebral cortex vas assuasd. On the basis of available
evidence this sean* a safe aeeunptloa (2, 23), Von, uben the aye is

39
presented with two alternating stimulus Lights forming the basis tor
lots wtiM, tbs light from sach of thsss Lights falling oo tbs ratios
gsnsrates a neural impulse which is thao tranmnittsd along the visual
pathways to the visual cortex, osar Brodnann's area J (23). Tbs
evidence indicates that each tins the light flashes, a traia of corti-
copetal neural iwpulsea is generated, and presumably ends in the
visual cortex. According to L. da go's (23) statistical nodal of the
visual pathways, these Inpulses nay bs retained in discreta pathways by
the processes of mention and inhibition. The nodal aeannes that a
relatively strong lapulea is necessary to fire a post-synaptic, eorti-
copetal neuron; this strength of impulsa any be called the "norma 1" one.
The neural net ef the retinae and cortex ace connected by a series of
neurons. A weak impulse, radiating along these branches, nay not have
the atreagth necessary to fire nova than one, directly connected post-
synaptic neuron. A neuron barely discharging above threshold although
impinging on ethers nay not fire then. This processing serves to pre
serve the discrete nature of the original stimulus object*
However, the nodal assumes both temporal and spatial sunaatiee.
The first assumption states that, for two neural impulses discharging
ea a post-synaptic neuron's dendrites la a particular temporal order,
end neither of which ate in thanoelveo ef sufficient intensity to fice
the poet-synaptic neuron, a si men t Inn nay produce a supra threshold
intensity and fire tbs neuron. Tbs aecoad assumption of spatial
summation states that given two subthreshold impulses which arrive on
separate dendrites ef tbs poet-synaptic neuron at the sans tine, nay

40
nauta through tha post-synaptic neuron, and thus firs it. It uw
probable that this for of summation (spatial) ia the visual system
paratas to provide a smooth, filled*ia projection of the external
stimulus field, hile the first, temporal summation, operates to provide
a smooth, continuous percept of real nation ia tha external stimulus
field.
Is this model, se tha stimulus lights for Bets motion are
driven at a vary low flash-rate, a.g., about 1 f/s, a nave of excitados
is sat up in tha retinae Cor each flash of each light* This, ia tun,
fires the succeeding corticopetal neurons, and the impulse eventually
ends on tha cortical neurona. Bat there is also a series of impulses
sat up which impinge on tha dendrites of the adjacent cortical aeurone
in tbs visual striata area. With such a low rata of flashing, these da
eat form tha sequence apparently needed for aumsatioe to taka place} ear
ace tha two stimulus lights dose enough together spatially so that the
impulses aroused by tha stimulation of tha retina impinge on the same
iaterauncial neurone. 4a tha flash-rate increased, tha impingamaat of
these impulses oa adjacent neurons becomes more and more frequent}
finally, a rate is reached which allows taaporal summation to taka
place. Then tbs area of stimulation ia spread a little, sad other
seta of internuncial aeurone begin to be given some subthreshold stimu
lation. Be the flash-rate is further increased, the seme merhenlsm in
volves more end more neurone. 4 locus of excitation is get up. 4a this
locos is enlarged with increasing flash-rate, it may begin to interact
with the locus which bee been eat up by the stimulating of the eacoad

41
stimulus light. Finally, the two loci in tha usual cortas iataract
through a "bead el neurons batwaaa than, and no loogar diacraCa point#
ara praaant. Tha parcapt under thaaa condition# nay ha al a ringla
light which wing# hack and forth, following in it# trajectory tha hand
oi stimulation which haa been canead by tha interaction of the loci eat
up by each light.
Thia neural iy oriented explanation seams to lit tha facta ob
tained in thia study for tha lower flash-rate threshold. It la con
sonant with tha Hading of tha highest correlation coefficients at tha
loara flash-rate threshold. After all, tha nervous ays ten does asee
to have rather stable ties constants under which auenation can take
place (23). The interpretation appears to be in agraanenf with tha
analyses of variance and the J test findings, both of which show that
there is no significant difference for ground at tha lower flash-rate
threshold; it is flash-rate which is the important paran#ter, and not
tha patterning of tha grounds through which the Beta ration takes place.
It is, than, a neural, rat a perceptual, phenomenon which takes place
at the lower threshold.
On tha upper limit of apparent notion there are statistically
significant differences in tha naans of tha motion seen against the
fixed grounds used In this study. These differences are in each case
between tha figured and the son-figured grounds. In coopering directly
tha obtained means for this mensura of apparent ration, it was found
that rare ration was seen on tha non-figured as coopered to tha figured
grounds. it was earlier hypothesised that thia might taka place on tha

taili of a (iMWtpkic] fivjtctlM of tho stimulus ground to tho cortos
in ouch o noy that tho non- figured ground would ptooent tho groo toot
possible nunbsr of alternative pot buoys by which apparent notion could
toko place. Therefore, no re notion should bo soon on this than on tho
other two grounds. Whether or not there noy bo strict *isomorphism" of
tho visual ground in oil its particulars nay not bo interpreted directly
froa this study. But by attaching the stripe of opaque paper to the
grounds tho illuninated oreo une reduced. One explanation of the
findings any bo that euanetion functions at end beyond the upper flesh*
rets threshold on e tenporal basis alone. Well defined lights flicker*
ing elaoet eiaultanoously produces two sensations. Sunmetloa by arse,
providing these areas are spatially sepe rated, foils to link the two
Vi *' t
defined brightness levels together into notion perception. in varying
the intensity for tho stiaulus lights, Saucer (30) found that intensity
did not affect the neon duration of notion. It sosas reasonable to
roleta this fact to this proble. Perhaps ground intoneity, not a
significant vsrlshls in itself, could operate only as s spatial variable
if it operated at all. The higher stimulation rata, with euanetion on
a tenporal basis st the cortical level, produced two flickering lights
and the upper Unit in reality represents a lower fusion threshold of s
special type. The ground proportion were supposedly effective in
poesihly altering fusion in term of tenporal aunnetloo. This study
suggests e central sensitisation on a tenporal basis at the upper nargla
of notion- no notion thresholds. The hypothesis of tenporal aunm
advanced by Borne, ot nl (15), ia partially supported in this study
tion

chapter v
SUMMARY
Two figurad (ranada, oaa vertically barrad aad a second tori*
eoataliy torrad, aad a non-figurad grauad ara uaad to dataraiaa tto
aaaa upper aad lorar flesh-rate thraatolda, aa optimal rato, aad tto
ranga of flash-ratea libia which tota apparent ration aay to aaoa.
Several hypotheses era developed: (l) ibera should to little ration
aera with tto vertically torrad ground, it eerviag ea a perceptual
barrier to the production ef apparent ration; (2) that tto horiaontally
barred ground abould have aa iaterradiate arauat of apparent ration,
tto horiaontal tora parallel to the path to to tabea by the tota ratioa
furnishing perceptual pathway* for ration; aad (3) that the on-
figured ground, by providing tto largest free area, should provide tto
raxiaua arauat of apparent ration.
The resulting erasures ware subjected to several statistical
aaalyaea consisting of tto Mans, tto standard deviations, tto standard
errors of tto rasas, Pearson praduct-rarant correlation coefficients
bateara pairs of tto rasuras, t ratios to evalate tto significance of
tto differences between tto obtained rasas, aad four coaplex aaalyaea
of variance to evaluate tto overeil significance ef tto sources of
variance, end t ratine corrected for correlation to evaluate tto
differences between tto esas of tto ensures of apparent ratioa, for
3d Op*
43

44
It wi found that no statistically significant differences
obtained between the grounds on tbs lower threshold, and for the opti-
1 flash-rate. Statistically significant differences were found at
the upper threshold and for the range within which Beta notion nay be
seen between the figured and the non*figured grounds used in this study.
Mo statistically significant differences were obtained between the
horIsontally and vertically barred grounds. Statistically significant
re were found between all the pairs of measures except for the optimal
flash-rate. This finding was related to the consistency of Os reports
and thus of the stability of the measures used. The finding of
statistically significant differences between the figured and the un
figured grounds at the upper threshold were related to a theory of
summation based on: (1) flash-rate, and (2) the area stimulated.
(This finding mis also related to L. ds No's theory of the statistical
nature of discrete stimulation on the visual pathways.)
A Gestalt interpretation of Beta-type apparent motion on the
basis of pragnana and of isomorphism was questioned. Temporal
processes at a central locua or loci may more readily be used for motion
and flicker-fusion interpretations.

APPENDIX A
GRAECO-LATIN SQUARE DESIGN
Order of
Backgrounds:
Subjects
Preeeetation
Plain
Vertical
Horiaoatal
Assigned
i
(Hale.
Vertical,
Horiaoatal)
1
2
3
is 4. 7. 10,
13, 14. 19,
22, 25. 28.
31, 34, 7A,
25A.*
2
(Horiaoatal,
Plain.
Vertical)
2
1
*
1
2. 5, 8, 11,
14, 17. 20,
23, 24, 29,
32, 35. 11A,
20A.
3
(Vertical,
Horiaoatal,
Plain)
3
l
2
3, 4, 9, 12,
13, 18, 21,
24, 27, 30.
33. 34, ISA,
18A, 27A.
Suffix indicates a replacaaout subject.
45

uniucKS
1. tartUy, 8. H. The relation of rocinal illumination to the
experience of movement. J. Bxner. fwchol., 1936, 1, 475*415.
2. Sortlay, 8. 8. Vision. A Study of It Baal. Haw York: Van
Hostrand, 1941,
3. Brown, J. V. Thresholds for vlaual movement. Psychol. Forach..
1931, 14. 249-248.
4. Corbin, 8, 8. Iba perception of grouping la apparent movement In
vlaual depth. ..ftggtoj,,, Jj. Y., Ho. 273.
9
5. Duncker, 8. Ubar indusiarta Bewegnung (Bin Beltrag aur Theorle
optinch Hahrgeaomnsner Bewegnung). Psychol. Forach.. 1929, \2,
180-259.
8.Billa, 8. 0. A Source Book of Geatalt Peycholonv. Hew York:
Harcourc, Brace, 1935.
7. Bxner, 8. Kxparimentelle Unterauebungen dar alafaackaan payebiaeban
Procesas. XII: Abbundluag: Oar peraonllchan Gleichung swelter
theil. £|iu8,,^rcA.^ga. Physiol., 1875. U. 403-432.
8. Gangarelll, J. 4. Apparent nmniat In relation to homonymous and
heteronymous stimulation of the cerebral hemispheres. J. Barer.
Psychol.. 1948, ft, 592-599.
9. Gilbert, G. M. Dynamic psychophyaice and the phi phenomenon.
Arch, Fayebo1. H. Y., Ho. 237.
10. Oottaebaldt, K. I: Ubar dan Binflase dar Brfahrung auf die
Vahrnabmuag von Figuran. Faychol. Forach.. 1924, 8, 261-317.
11. Gottschaldt, K. 11: Uber dan Binfluaa dar Brfahrung auf die
Wahrnehmwng von Figuren. Faychol. Forach.. 1929, 1, 1-87.
12. Guilford, J. F. and Unison, a. Bye movements and the phi-
phenomenon. Am. J, Faychol.. 1929, 595-606.
13. Hartmann, 0. 8. gestalt. Psychologic jugaz^of. Fagta and
Principias. Haw York: Ronald, 1935. Fp. 23-30; 125-126.
14. Hartmann, L. Beue Varacfamalauagaproblema. Favchol. Forach..
1923, 2, 319-396.
46

47
15. Horas, K. F., Wilson, S. R., Saucer, R. T., and Reichenberg, H.
Temporal luantioo aa a theoretical basis of apparent notion.
Paper read at Southeast Psychol. Assoc. (Physiol. Sec.),
Atlanta, May, 1951.
ft
16. Koffka, t. Ubsr den Menachsn Kreiabogenveraucb. In Koffiui, R.,
Kleine Mittleungen aus den Psychologischen Institu der
Universltat Geissen. Psychol. Forach.. 1922, j$, 144-155.
17. Koffka, R. Principles of Gestalt Psychology. Sen York:
Hercourt, Brace, 1935.
IB. Rorte, A. Kinenatoskopiache untersochungsn. Zelt. f. Psychol..
1915, 72, 193-296.
19. Lindquist. B. P. Desijp. and .S^ri^t _in_Psj;chqioM
and Education. Boston: Houghton, Mifflin, 1953. Pp. 220-244;
258-265.
20. Links, P. Die Sttoboskopischen Tauschaungen und des Problen yon
Bewegung. Psychol. Stud.. 1907, J, 523-524.
r
21. Links, P. Crundgragen der Wehraehmunglehre. Munich: B. Reinhardt,
1918. Pp. 269-360.
22. McHensr, Q. Psychological Statistics. 2d Ed. New York: Wiley,
1955.
23. Morgan, C. I., and Stellar, S. Physiological Psychology. 2d Bd.
Hew York: McGraw-Hill, 1950. Pp. 67-74; 77-79.
24. Seff, W. S. A critical investigation of the visual apprehension
of novenent. An. J. Psychol.. 1936, 48, 1-42.
25. Orlansky, J. The effect of similarity and diffarence in font on
apparent visual movement. Arch. Psychol. H. Y.. Ho. 246.
i 26. Reichenberg, H. Apparent motion as a function of form. Un
published M. A. Thesis, Departmsnt of Psychology, University
of Florida, 1953.
27. Reichenberg, H. Apparent notion as a function of instruction,
form and rate of stimulation. Unpublished Ph.D. Dissertation,
Departmsnt of Psychology. University of Plorida, 1957.
28. Rubin, B. Visualle Wahrgeoomaeoe Figuren. Copenhagen:
Gyldenalska, 1921.
I 29. Saucer, R. X. The effect of dark adaptation upon the perception
of apparent notion. Unpublished M. A. Thesis, Departmsnt of
Psychology, University of Florida, 1950.

48
v 30. Saucer, ft* T. The effect: of roto and energy upon the percept loo
of apparent notion. Unpublished Ph. D. Dissertation. Department
of Psychology, University of Florida, 1954,
31. Smith, K. ft. Visual apperent soveasot in the ebeence of neural
interaction. Am, J. Psychol., 1948, 73-78.
32. Smith, ft. U. The neural centers concerned in the amdiatlon of
apperent movement vision. J. 8roer. Psychol.. 1940, 6, 443*468.
' J
33. Stratton, G. H. The psychology of changet how is the perception
of movement related to that of succession. Psychol. Rev.. 1911,
1§, 262*293.
34. Vernon, H. 0. A aUfAMSi ***$*££&>* Cambridge
University Frees, 1952.Pp. 46-73} 149-153/
35. Wendt, P. ft. Development of en eye camera for use with motion
pictures. Pevchol. Monoar.. 66, Ho. 339.
, i 1 V t
yg.
36. Wertheimer, M. gxperimentelle Studian uber dee Sehen von
Dewegnuagen. 2it. f. Psychol.. 1912, 61, 161-265.
, , . v : t v . i : . * - v ,
37. Wilson, S. ft. The relationships between measure# of cortical
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Thesis, Department of Psychology, University of florida, 1955.
38. Wilson, 8. ft. Bato and dark adaptation ss determinants of apparent
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ftev. od. Row Torhi Kelt, 1954. P. 375.

BIOGRAPHICAL ITIMS
The writer mi bora on March 2, 1926, at Iron too, Ohio. Ho
pursued hit undergraduate studies at the Ualvarsity of Florida, re
ceiving the B.A. degree June 7, 1954. He entered the Graduate School
at the University of Florida, receiving the M.A. degree in the College
of Arte end Sciences, Department of Psychology, June 4, 1954.
He has served as e graduate assistant in the Department of
Psychology,as e research and laboratory assistant fron Septcaber, 19)5,
to Septeaber, 19)7, whoa he received a Fellowship under the Vocational
Be habilitacin Traineeship program. He is currently serving as a
trainee in the Veteran's Administration program in Psychology.
Zn 19)5 he was elected to the Seta chapter. Alpha Kappa Delta,
Honorary Sociology Fraternity. Zn 19)6 he was elected to aaabershlp
in the Florida Psychological Association. He was elected to associate
membership in the American Psychological Association in 1958.

This dissertation ss prepared under the direction of the
chaimea of the Supervisory Couartttee end has been approved by ail
nsabers of the coasdttee. It nee outwitted to the Dean of the College
of Arts end Sciences and to the Graduate Council end wee approved as
partial fulfillnsat of the requirenents for the degree Doctor of
Philosophy.
January 31, 1959
Dean, College of Arts end Sciences
Dean, Graduate School
SUPERVISORY COMMUTES:
t L.\4^tu
2/(J/ /(/ *7*
^0^ /S*



19
Legend: A Electronic Control Switch
B Gerbrand Paper Tape Recorder
C E's Position
D Light Tight Equipment Booth
E Stimulus Light Panel
F Gerbrand Recorder Control Key
G Optic Bench
H Chin Rest
I O's Position
Fig. 2.--Block Diagram of the Experimental Room


31
tha affects of order of pceooatatloa sad of tho ground upon tbs
nssuranant of optlnnl flesh-cats of apparent satioo on presented in
Tsblo 4. It soy bo soon that aoao of tbo variables approached statisti
cal significance. Iban foco, neither order of proseo tat ioa nor grand
was a significant source of variation ia the dotamiaatioo of this
Measure of Beta-typo of apparent Motion,
Tbo third analysis of variance is presented ia table 5, The
fined variables More order of presentation end ground, topi lest ions
fecned a randomly distributed variable. The upper flash-rote threshold
of Bate notion nee the dependent variable. As nay be seen fren the
table, the grounds vara significant source of variance upon the Beta
notion at its upper threshold (| ^ .01). It nay be concluded that the
grounds vera e significant detemiaaat of this Measure. Again the
order of presentation (practice effect) use not e significant source of
varanos, nor vers the interactions. The grounds alee fern the ns jar
source of variance.
The last analysis of varanos on the range of cutes within which
Beta notion wee seen ia presented ia Table A. Of the sources of vari
ance ia this Measure of Befe notion only the grounds ware statistically
significant (f < 0.0B5). It should again be noted that there was no
statistically significant variation attributable to the order of
presentation of the grounds. Her was the interaction of the ground and
order ef presentation statistically significant. Fran this it van
concluded that the practice effects were effectively controlled ia this
erperlnantel design*
A aeries of ratios, corrected according to Mcflnaer'a (22)


32
TABLE 4
ANALYSIS OF VAE1AJCB FO& VARIABLES MODIFYING
OPTIMAL PLASH-RATS: GROUNDS X ORDER OF
PRESENTATION X REPLICATIONS
Source
M
4f
-
l
ratio
X
1
Grounds (6)
1*40
2
0.70
1.21
m
Ordnr of fnnaUtion
<0)
0.04
2
0.03
V"*
0.02
m
lafUcatim
U.SO
11
1.07
m
m
m
G X 0
i.n
4
0.44
-gorgor
0.81
m
6 X R
12.71
22
0.58
*
m
m
0 X X
35.80
22
1.43
8

m
G X 0 X X
33.54
44
0.54
m
m

Within Calls
0.00
0
an
m
m

Total
87,08
107
m

m
on


CHAPTER XV
DISCUSSION A CONCLUSIONS
The ovsr-aii effect of chance la gEwnd for the upptr threshold
see significant statistically. This say he interpreted as that the
grounds did chsngs one Halt ef Beta notion. The differences hotos so
the non*figured and the borisontally barred, and the non-figured and
the vertically barred grounds, were significant. It oes found that
ths assn flash-rate for the non-figured ground oes 5.26 f/s, ohlle the
horlaoetal sad vertical grounds vote 4.68 f/s and 4.62 f/s respectively.
In asintaiaing notion perception a higher cate of action one tolerated
by ths £ for the plain la conparlsoa with the figured grounds. These
differences were statistically significant. The finding is consonant
with the hypothesis that acre action say be obtained free the non-
figured then iron ths figured grounds. The hypothesis that there would
be a differential perception of Beta notion for the horlaoetally barred
as coopered with ths vertically barred grounds oes rejected.
The other dependent variable for which ground was significant
ass mags. Tbs mage one aodifled as inly by the elevation of rate in
the upper Unit. Them warn no statistically significant differences
betwain the aeons of ths aoaeures for the grounds at the lower threehold
nor in the opt Iasi flash-rate. Them oem no statistically significant
differences between the horinontally barred and the vertically barred
27


CHATTER I
XHTROOUCTIOM
The purpoM of thia study is to lavestlgste tbs offsets of
certain characteristics of flood grounds upon the perception of Beta-
type notion. In perception, figure-ground relationships here been
known end often reported; however, these noet often involve static, un-
noving perceptions (11, 2f). Barely have they keen concerned with
figure-ground effects in e dynamic field ee represented by the phi-
phenomenon (). There have been no specific Investigations of fined
variate ground effects on the perception of apparent notion of the
Beta-type.
The Beta notion is a relatively single perception which is far-
reaching in its theoretical importance. If an 0 is presented with two
fleshing lights, the flash relationship being such that ee one light,
"A", goes off, e eecond light, MB, gone on, the perception nay be that
of e single light which noves from the first position to that of the
second (34). If the relationship is continuous, i.e., ABABABAB ...
AB, the perception nay be that of e single light which noves backward
and forward between the two positions. It nay appear to nove in e two-
dimensional plane, or in e three-dimensional path. This is the Bate
phenomenon (33).
There ere e number of variables involved ee earlier experiments
have shown (A, 4, 14, 24). The flesh rate in terns of couplets cycles
1


33
TABU 3
ANALYSIS Of VARIANCE FOR VARXABUS MODIFYING
UTTER FLASH-RATE THRESHOLD: GROONOS X
ORDER OF FRESSNEATION X REPLICATIONS
Ground* (G)
8.90
2
4.43
-c'-e*
5.84
Order of Presentation (0)
0.00
2
0.40
V^OR
0.10
Replications (R)
43.90
11
4.17
4
G X 0
4.14
4
1.04
W*^Q0R
1.17
G X R
14.41
22
0.74
m
m
0 X R
7.32
22
3.97
m
m
6 X 0 X R
39.04
44
0.89
m
m
Within Call*
0.00
0
m
m
m
Total
202.73 107


7
inatar tendency toward induced notion. It eeene reesonable to
interpret hie findings ee dealing with figure-ground relationships.
The fixated figure can be considered to be in sharp focus, the non-
fixated figure less so. The one is seen as figure, bile the other
tends to bacons ground. His findings then indicate that the ground is
stable, but that the figure is susceptible to the induction of notion.
The ground any be considered to Com an anchor for the figure t the
figure is seen to am against a ground. If the fixated figure is the
enclosing figure, then notion is less likely to be induced. This eeene
to indicate that the enclosing figure, although fixated, is yet seen as
ground, and not as figure. However, this interpretation aaana the nost
logical one in terns of the Gestalt principle of orasnans. Bartnana
(13), while he discussed the exparlnent, does not answer this interpre
tation, nor does Duncker.
The experinant Koffka (16) perfomad wee in refutation of Linke's
(20, 21) earlier work. Linke's Of were presented with e perisphere
(a ami circle with a depreseed center, the erne pointing up) on which
was drawn a dot. In a succession of presentations, the dot was placed
in a series of intimadlate positions around the perisphere. The
perception was that of a dot rolling around in a aeniclrcle against a
fixed ground. Links interpreted his findings as being an Interpretation
of the percept by the 0 based upon his pest experiences, e.g., such as
seeing a bell roll around the inside of a bowl. Apparent ant ion,
for Links, was net a given fact, but was Inferred iron pest experience.
Koffka (16), in a neat reversal of the experinant, refuted
Linke's interpretation but confirmed his findings. Koffka presented


26
at J 1(5, U my be stated that the true mao rate for the upper
threshold of the we*fipind ground me 5.26 f/s, 0.18 f/e. The
lower threshold use 1.71 f/e, i 0.12 f/e, and the man optimal rate me
5.21 f/e, t 0.14 f/e. The range ot rates within which epparent motion
is seen wee 5.55 f/e, 2 0.23 f/s. Similar etatemte my he mde for
the mm rates for upper thresholds, lower thresholds, optiml rates,
sad the range of rates within which apparent wot loa is seen for the
It.' -* 1 1 1 '
other grounds.
The s tends rd do wist ions of the distributions for the serious
grounds and mesures of lets notion were confuted according to the
standard net hod given in Melonar (22). These values are suamrlsed in
Table 1. Thus, for the upper threshold of the non-figured ground, the
mm me 5.26 f/e, l 1.07 f/e. Sinilar Interpretations held for the
other values and for the various grounds.
ns number of & entering into them confutations wee, in all
conditions, 36.
> : . V . /Mm
Pearson product meant correlation coefficients between pairs of
mesuras ware confuted according to Mclsmr'e (22) nodal and are
reported in Table 2. Them my be interpretad as mesuras of the eon*
eistency with which the & reported fren one mature to another for the
various grounds. They are in a seam e manure of the stability of
the naaaures them si ves, if it can he assumd that the Jg| were consistent
in their reports. Presumably, a perfectly stable mesure, coefficient
*, i /
of 1.00, should yield the earn performance value irrespective of the
conditions under which it operates. Any inconsistency then would be e
divergence toward aero from this correlation. As my be seen from the


48
v 30. Saucer, ft* T. The effect: of roto and energy upon the percept loo
of apparent notion. Unpublished Ph. D. Dissertation. Department
of Psychology, University of Florida, 1954,
31. Smith, K. ft. Visual apperent soveasot in the ebeence of neural
interaction. Am, J. Psychol., 1948, 73-78.
32. Smith, ft. U. The neural centers concerned in the amdiatlon of
apperent movement vision. J. 8roer. Psychol.. 1940, 6, 443*468.
' J
33. Stratton, G. H. The psychology of changet how is the perception
of movement related to that of succession. Psychol. Rev.. 1911,
1§, 262*293.
34. Vernon, H. 0. A aUfAMSi ***$*££&>* Cambridge
University Frees, 1952.Pp. 46-73} 149-153/
35. Wendt, P. ft. Development of en eye camera for use with motion
pictures. Pevchol. Monoar.. 66, Ho. 339.
, i 1 V t
yg.
36. Wertheimer, M. gxperimentelle Studian uber dee Sehen von
Dewegnuagen. 2it. f. Psychol.. 1912, 61, 161-265.
, , . v : t v . i : . * - v ,
37. Wilson, S. ft. The relationships between measure# of cortical
activity and measures ef apparent motion. Unpublished K. A.
Thesis, Department of Psychology, University of florida, 1955.
38. Wilson, 8. ft. Bato and dark adaptation ss determinants of apparent
motion. Unpublished Ph* D. Dissertation, Department of
Psychology, 1957*
39. Woodworth, ft. 8., and Schloaberg. H, fepeylflffiUft* ..fXffMgffir
ftev. od. Row Torhi Kelt, 1954. P. 375.


taili of a (iMWtpkic] fivjtctlM of tho stimulus ground to tho cortos
in ouch o noy that tho non- figured ground would ptooent tho groo toot
possible nunbsr of alternative pot buoys by which apparent notion could
toko place. Therefore, no re notion should bo soon on this than on tho
other two grounds. Whether or not there noy bo strict *isomorphism" of
tho visual ground in oil its particulars nay not bo interpreted directly
froa this study. But by attaching the stripe of opaque paper to the
grounds tho illuninated oreo une reduced. One explanation of the
findings any bo that euanetion functions at end beyond the upper flesh*
rets threshold on e tenporal basis alone. Well defined lights flicker*
ing elaoet eiaultanoously produces two sensations. Sunmetloa by arse,
providing these areas are spatially sepe rated, foils to link the two
Vi *' t
defined brightness levels together into notion perception. in varying
the intensity for tho stiaulus lights, Saucer (30) found that intensity
did not affect the neon duration of notion. It sosas reasonable to
roleta this fact to this proble. Perhaps ground intoneity, not a
significant vsrlshls in itself, could operate only as s spatial variable
if it operated at all. The higher stimulation rata, with euanetion on
a tenporal basis st the cortical level, produced two flickering lights
and the upper Unit in reality represents a lower fusion threshold of s
special type. The ground proportion were supposedly effective in
poesihly altering fusion in term of tenporal aunnetloo. This study
suggests e central sensitisation on a tenporal basis at the upper nargla
of notion- no notion thresholds. The hypothesis of tenporal aunm
advanced by Borne, ot nl (15), ia partially supported in this study
tion


15
t approslaataiy 55 uiUaaparaa (aa.) lt yields approslaataiy a daylight
apoctrua. As tbs plata current la decreased, the omitted light shifts
toward tha long wave-length and of tha spectrum, i.a., toward tha rada.
Viriag af tha tuba baeoaaa erratic below 5 aa. plate currant. Tha
brightness of tha two tubas was equated pathologically, rather than
by watching plate currants. It was found that slight differences be*
tween tubas in light output at identical plate currents preclude tha
use of plate current asaauresents alone being used to equate tha lights.
Fleta currants in this study ware bald between 12 and 15 aa. la
aounting tha &1130B tubas in tha light panel, a lens systaa was used
to provide parallel aalssion of tha light rays on tha diffusing screen.
An aperture was designed to Halt tha visual angle subtended by tha
stiauius lights to 5 at one aster (a.) froa tha 0; however, due to
diffusion through tha ground glass screen, tha angle was approslaataiy
6, as asasured at tha outer Halt of tha disc of light.
Three grounds ware constructed for use in this study. One was
plain, i.a., non-figurad. A second consisted of parallel, opaque and
translucent 7 an. stripes in a horiaontal arrangaaent alternately
placed. The third was constructed with stripes of ease width alter*
acting opaque and translucent vertical hands. These grounds were
constructed by gluing 7 aa. stripe of black construction paper spaced
at 7 an. te Talos tracing paper. The black stripes ware quite opaque,
very sharp, and of equal width throughout their length. The Talos
tracing paper provided a gralaicas, translucent area through which wee
projected the light froa tha 11130B tubes, and the light used to


BIOGRAPHICAL ITIMS
The writer mi bora on March 2, 1926, at Iron too, Ohio. Ho
pursued hit undergraduate studies at the Ualvarsity of Florida, re
ceiving the B.A. degree June 7, 1954. He entered the Graduate School
at the University of Florida, receiving the M.A. degree in the College
of Arte end Sciences, Department of Psychology, June 4, 1954.
He has served as e graduate assistant in the Department of
Psychology,as e research and laboratory assistant fron Septcaber, 19)5,
to Septeaber, 19)7, whoa he received a Fellowship under the Vocational
Be habilitacin Traineeship program. He is currently serving as a
trainee in the Veteran's Administration program in Psychology.
Zn 19)5 he was elected to the Seta chapter. Alpha Kappa Delta,
Honorary Sociology Fraternity. Zn 19)6 he was elected to aaabershlp
in the Florida Psychological Association. He was elected to associate
membership in the American Psychological Association in 1958.


10
la ti direction of t)lr coal notion. At crtala In to rood loto o poo do,
>
tho te reportad the rectangles aovlng la a direction oppoolta to the
direction of their objective ement, Krooa Interpreted hie findings
correctly os a true example of apparent sot ion.
The purpose of the preeeat etudy le to lnveetlgote the effecte
of crtela determinants of ground upon the perception of Beta notion.
It has been shown la a number of experiments that ground has an
important effect on the percept. Thera era a number of determinants
of ground and figure relationships detailed by the Gestalt writers.
Among the principles determining the percept of figure are those of
clearness: the figure Is more sharply defined than Is the ground.
The ground Is the lose distinct of the too. and tends to he Ignored la
reports of the percept. The figure Is morn Interesting or lively then
the ground, and seems to stand out from the ground; the ground seems
to continue behind and to he hidden by the figure. These principles
are grouped under the general heading of ernsnana: the moenlagfulness
of the parts of the percept (4, Id).
A second principle Is that of comean destiny: the figures and
the ground seem to share an end comnon to both. Thus, if a vertically
barred ground Is presented against which Beta motion Is to be seen,
these vertical bars can be thought to shore a rnnman destiny with the
percept of apparent motion (6, 14). Under the principle of prsgnans.
such e ground should form a barrier to the continued perception of
apparent notion because it forces the apparently mowing stimulus lights
to cross successively a aeries of dark and light stripes. Conversely,
a ground which contains stripes of light sad dark arranged horiaoatally


34
TABLE 6
ANALISIS OP VARIANCE VOS VARIABLES M09Z7Y1SS SAKE Of MOT IDS:
GROUNDS X OROSE OF PRESENTATION X RSILICATXD8S
Sou vet
se
it
-
l
ratio
l
1
\
Ground (G)
11.07
2
5.54
5.45
0.025
Order of Presentation (O) 1.37
2
0.48
**0/0E
0,11
40
Replications (R)
30.10
11
4.55
#
m
40
G X 0
4.92
4
1.23
^gor
1.05
m
OSS
21.51
22
0.98
OS

m
0 X R
132.15
22
6.01
4
m
m
G X 0 X R
51.49
44
1.17
m
m
m
Within Calls
0.00
0
4
m
m
m
Total
272.41
107
m
Mi
a
m


4
Gengerelli (8) investigated the effect of heteronymous end
hewayoui stimulation of the trete cortex la ea attempt to answer
thie problem of interact loa. By heteronymous stimulation he meant
preeentlng the stimulus lights la such e meaner ee to etlmelete the
striate cortex in both hemispheres. Homonymous stimulation occurred
hen stimulation took piece la only one hemisphere. Me uead e split-
field technic hy mesas of half-silvered mirrors. Be presented different
stimuli to each eye. Underlying this tchale le the assumption of
spatial projection of areal stimulation through the optic chiasms, the
lateral geniculate bodies, the optic radiations, and the atriste cortex,
with the preservation of patterning la ell these structures (23). Under
these conditions, he found that hie Os saw the largest amount of
apparent motion under the hosunynoue condition. He ascribed hie
findings to the Interaction of neural fields taking piece la the cortex,
sad not la the subcortical structures of the visual corticopetel path
ways. However, his findings were questioned by Sslth (31).
Smith (31) presented hie Os with two lights which were mounted
on e headband. The lights were adjusted in such e meaner that the
Images formed hy the lights were on the extreme nasal borders of the
retinae. Only one light could be seen by either eye. This mode of
presentation resulted la the stimulation of t extreme borders of the
striate cortex, bordering an the calcarine fieours. This etimaletloa
thus gave the maximum possible separation of the erees of stimulation
of the cerebral cortex. Nevertheless, he obtained from hie Os good
perception of apparent motion. He Interpreted hie findings ee ruling
out neural field Interactions on both the peripheral end central levels.


47
15. Horas, K. F., Wilson, S. R., Saucer, R. T., and Reichenberg, H.
Temporal luantioo aa a theoretical basis of apparent notion.
Paper read at Southeast Psychol. Assoc. (Physiol. Sec.),
Atlanta, May, 1951.
ft
16. Koffka, t. Ubsr den Menachsn Kreiabogenveraucb. In Koffiui, R.,
Kleine Mittleungen aus den Psychologischen Institu der
Universltat Geissen. Psychol. Forach.. 1922, j$, 144-155.
17. Koffka, R. Principles of Gestalt Psychology. Sen York:
Hercourt, Brace, 1935.
IB. Rorte, A. Kinenatoskopiache untersochungsn. Zelt. f. Psychol..
1915, 72, 193-296.
19. Lindquist. B. P. Desijp. and .S^ri^t _in_Psj;chqioM
and Education. Boston: Houghton, Mifflin, 1953. Pp. 220-244;
258-265.
20. Links, P. Die Sttoboskopischen Tauschaungen und des Problen yon
Bewegung. Psychol. Stud.. 1907, J, 523-524.
r
21. Links, P. Crundgragen der Wehraehmunglehre. Munich: B. Reinhardt,
1918. Pp. 269-360.
22. McHensr, Q. Psychological Statistics. 2d Ed. New York: Wiley,
1955.
23. Morgan, C. I., and Stellar, S. Physiological Psychology. 2d Bd.
Hew York: McGraw-Hill, 1950. Pp. 67-74; 77-79.
24. Seff, W. S. A critical investigation of the visual apprehension
of novenent. An. J. Psychol.. 1936, 48, 1-42.
25. Orlansky, J. The effect of similarity and diffarence in font on
apparent visual movement. Arch. Psychol. H. Y.. Ho. 246.
i 26. Reichenberg, H. Apparent motion as a function of form. Un
published M. A. Thesis, Departmsnt of Psychology, University
of Florida, 1953.
27. Reichenberg, H. Apparent notion as a function of instruction,
form and rate of stimulation. Unpublished Ph.D. Dissertation,
Departmsnt of Psychology. University of Plorida, 1957.
28. Rubin, B. Visualle Wahrgeoomaeoe Figuren. Copenhagen:
Gyldenalska, 1921.
I 29. Saucer, R. X. The effect of dark adaptation upon the perception
of apparent notion. Unpublished M. A. Thesis, Departmsnt of
Psychology, University of Florida, 1950.


chapter v
SUMMARY
Two figurad (ranada, oaa vertically barrad aad a second tori*
eoataliy torrad, aad a non-figurad grauad ara uaad to dataraiaa tto
aaaa upper aad lorar flesh-rate thraatolda, aa optimal rato, aad tto
ranga of flash-ratea libia which tota apparent ration aay to aaoa.
Several hypotheses era developed: (l) ibera should to little ration
aera with tto vertically torrad ground, it eerviag ea a perceptual
barrier to the production ef apparent ration; (2) that tto horiaontally
barred ground abould have aa iaterradiate arauat of apparent ration,
tto horiaontal tora parallel to the path to to tabea by the tota ratioa
furnishing perceptual pathway* for ration; aad (3) that the on-
figured ground, by providing tto largest free area, should provide tto
raxiaua arauat of apparent ration.
The resulting erasures ware subjected to several statistical
aaalyaea consisting of tto Mans, tto standard deviations, tto standard
errors of tto rasas, Pearson praduct-rarant correlation coefficients
bateara pairs of tto rasuras, t ratios to evalate tto significance of
tto differences between tto obtained rasas, aad four coaplex aaalyaea
of variance to evaluate tto overeil significance ef tto sources of
variance, end t ratine corrected for correlation to evaluate tto
differences between tto esas of tto ensures of apparent ratioa, for
3d Op*
43


23
followed the directions, and eea eliminated fren the study. For each
0 lost from tbs study, s replacement 0 eea completed. The criteria
for tbs replscsesnt 0 were tbs sees as for tbs original 0, and tbs ase
g ees placed in tbs sans call of the Graeco-Latin Square.
Tbe upper aad loser flash-rate thresholds, optleal flash-rate,
and the rungs eitbin which Bata notion is seen constituted the asasurca
usad la this study. Tbs lower flash-rata threshold for Bata notion is
deflnsd as that rata bsloe which the g reports lass then 50 per cent
apparent notion. Below threshold, psychologically, the percept breaks
down into two lights which are alternately illuminated. Similarly, tbs
upper flash-rate threshold nay he defined as that rata shows which Beta
notion is not Man. For this study, "not seen" is defined as a report
of Bata notion for less than half the tins in any one trial. Again, at
the threshold the typical Bata notion percept is replaced by an entirely
different one; in this case, an 0 reports seeing two lights which are
siaultaaaously oe and flickering.
Optinal flash-rate is defined as that rata which produces the
greatest reported amount of Beta notion, expressed as a percentage of
the total. Thus, it is a rate at which tbe notion is seen nost con
tinuously by the g, and in which the notion nost nearly approaches the
percept of real notion.
The statistical analysis of the date included the computation
of the neena for all the groups for the three grounds, the standard
deviations of tbs distributions, tbs standard errors of tbs titans.
Fearaoa product-aoaaat correlation coefficients, g ratina baaed on the
correlation coefficients, end four complex analyses of variance (If, 22).


21
tins* for the three grounds.
During nek trial, cha 0 n instructed to hold the telegraphic
key down during Che tine he was perceiving Beta notloa, and Co release
. < t .
it bes Che perception use of Cvo lights fleshing, one fined light on
with the other off la cycle, or the shadow notion pheaonsaon. The use
of the key la this asonar placed a distinctive record of Beta ootloa
upon the Gerbrand tapa* Since the tape waa driven at a constant speed,
1 SEff * 1
e staple transfonation converts distance along tha tape to e tloa
aoasureaeat. Each olnute trial of motion la then converted to a per
cent tine by the equation:
H = (100)
la which t£ la tha aaount of apparent notion each subject perceived
during a trial, da, la tha distases along the tape during which ha
held the key down (waa perceiving ootloa), and D la the total distance
along tha Upa of each trial (tloa). The product la expressed as s
percentage of tha elan In which apparent notion was perceived.


APPENDIX A
GRAECO-LATIN SQUARE DESIGN
Order of
Backgrounds:
Subjects
Preeeetation
Plain
Vertical
Horiaoatal
Assigned
i
(Hale.
Vertical,
Horiaoatal)
1
2
3
is 4. 7. 10,
13, 14. 19,
22, 25. 28.
31, 34, 7A,
25A.*
2
(Horiaoatal,
Plain.
Vertical)
2
1
*
1
2. 5, 8, 11,
14, 17. 20,
23, 24, 29,
32, 35. 11A,
20A.
3
(Vertical,
Horiaoatal,
Plain)
3
l
2
3, 4, 9, 12,
13, 18, 21,
24, 27, 30.
33. 34, ISA,
18A, 27A.
Suffix indicates a replacaaout subject.
45


u
o that tha tripa* lia paralia1 to tha anticipatad path of apparant
notion should fcil itata tha parca pt by Coming pathways. A ini lar
parcapt aaana to have occurred in Koffka'a (16) experlsamt.
A third principia with which this experiaent daala la the
Oaatalt principia of laonorphiaat tha rapraaantation in neural alaaanta
of tha aanaory etiaulus with praaarvatlon of tha GastaIt of that atiaulus
field (6, 16). Thus, translating tha previously presented nodels into
lsonorphlc tarns, one would expect that tha vertically barrad gratad
would stlaulate selectively neural alaaanta, and that there would ha
a preservation of its Com in tha patterning of the atiaulation. For
axaapla, such a ground as the vertically barred one discussed previously,
would sat up alternating bands of excitation and quiescence in tha
; it
striata eortsx in an exact analog of tha original at inulus. Such a
continuing stinulus as la presented by Bata nation would produce an
interacting neural field ouch that a continuous band of excitation
would cross and recross the cerebral cortex in exact neural represen
tation of the percept of the notion as reported by the 0.
Zf the interaction of neural fields set up by the stinulus lights
is necessary for the percept of apparent notion to take place as is
denaaded by tha Gestalt theory, then it scene likely under the principles
Just outlined that certain types of cortical fields should act to in
hibit or to facilitate the perception of apparent notion. In line
with a Gestalt theory of apparent notion, bands ef quirsoeete ard ex
citation should be set up in the cortex (strictly speaking, in tha
neurons asking up the cortex) by that ground corresponding to the


18
block diagram of the cooa and apparatus is shorn in Pig. 2.
Sf,Pratue.~A telegraphic key was mounted conveniently
for the 0 within the optical bench tunnel and connected through a
suitable power supply to the recording relay of a Garb rand waxed-paper*
tape signal recorder. The g placed dietiactlve signals on the tape at
the beginning aed id of each trial. These were used to locate each
trial. Oaring a trial, 0 pressed the key down aa long as ha wee
perceiving Beta notion. Since the paper tape wee fed through the
recorder at a constant speed, distance along the tape wee translated
to tine and the aeount of apparent not ion reported under each condition
issss&m
Observers consisted of 36 young adults of college age who showed
no obvious signs of brain dnaegt.
lack 0 was given instruction and several orientation trials
prior to the beginning of the axperleent proper. During this period
oe ground or rate ueed in the experiment wee preseated to the 0. it
wee found that neat Os had considerable difficulty in differentiating
Bote notion free the shadow-notion phenomenon at the higher flash-ratee*
Conoide reble training wee foued necessary for the g to render an
accurate, reliable report of his perceptions. During these orientation
trials, the Os were instructed in the use of the telegraph key con
trolling the Cerbrand recorder.
Bach g was given four min. of dark adaptation prior to the
beginning of the experiment proper.


24
Tbs Mans wan confutad according to Cha standard fornula given
in McBsnar (22) and an reportad in tabla 1 fot Cha lanar flash-race
threshold, cha naan rata my be interpretad at that value below which
Bata notion la not seen. Thus, for Che non-figured ground, Che value
la 1*71 f/a. The value of cha lower linaa for cha vertically barred
ground is 1.77 f/a, and for Che horiawa tally barred ground, 1.75 f/a.
The upper threshold's wean value way be Interpreted as being that value
above which Bate notion la net sees. For Che non-figured ground, chin
value la 5.24 C/e, while for the horlaontally barred ground it la 4.68 f/a
end for the vertically bamd ground it la 4.62 f/a.
The opt Inal rate bee been defined ee the rate at which the 0
sew the greatest per cent tine of apparent notion, using the nodal value.
For the non-figured ground, this was 3.21 f/e. For cha horlaontally
hatred ground, the value wee 3.10 f/e, while for Che vertically barred
ground it wee 2.63 f/e. It wee at these values that note Og aaw the
largest anount of apparent notion.
The range, the difference be twees the upper end lower llama,
sumarias* aa a singla value the range of rates in this study at which
Beta natos wee asen. These ranges, aleo reported in Table 1, for the
non-figured ground was 3.55 f/a, for the vertically barred ground wee
2.85 f/e, dille that for tha horlaontally barred ground was 2.93 f/s.
W was desired to obtain eons satnate of the diapersion around
these values. To evslusts this, tbs standard errors ef the naans wars
confuted (19, 22). These give en satnate of values within rhleh, at
a stated fiducial liadt, the true neon of the universe of neena fren
which these obtained naans ware drawn. Setting these fiducial Units


25
TABLE 1
MEASURES Of BETA HOT IOS ACCORDING TO GROUND PROPERTIES

X
OoDtr Flaah-Rata Threshold
Hon-figurad Ground
36
5.26
1.0?
0.18
Siciaottttl
36
4.68
1.44
0.24
Vortical
36
4.62
1.46
0.24
Boa-figurad Ground
36
3.21
0.86
0.14
Horiaontal
36
3.10
1.00
0.17
Vortical
36
2.§3
0.80
0.13
Non-figurad Ground
36
1.71
0.70
0.12
Horizontal
36
1.75
0.60
0.10
Vertical
36
1.77
0.66
0.11
iMLS&HSitt
Boa-figurad Ground
36
3.55
1.36
0.23
Boriaoatal
36
2.93
1.67
0.28
Vortical
36
2.85
1.62
0.27


44
It wi found that no statistically significant differences
obtained between the grounds on tbs lower threshold, and for the opti-
1 flash-rate. Statistically significant differences were found at
the upper threshold and for the range within which Beta notion nay be
seen between the figured and the non*figured grounds used in this study.
Mo statistically significant differences were obtained between the
horIsontally and vertically barred grounds. Statistically significant
re were found between all the pairs of measures except for the optimal
flash-rate. This finding was related to the consistency of Os reports
and thus of the stability of the measures used. The finding of
statistically significant differences between the figured and the un
figured grounds at the upper threshold were related to a theory of
summation based on: (1) flash-rate, and (2) the area stimulated.
(This finding mis also related to L. ds No's theory of the statistical
nature of discrete stimulation on the visual pathways.)
A Gestalt interpretation of Beta-type apparent motion on the
basis of pragnana and of isomorphism was questioned. Temporal
processes at a central locua or loci may more readily be used for motion
and flicker-fusion interpretations.


8
kii te with a alalia* design, but with tba a pax of tha parlaphara
pointing upward and tba ana downward. Tba perception raportad by bia
Of waa exactly tba sane aa tfaoaa ra portad by L. lake's, but, of coursa,
paat experience could not now bo coaaldarad a baala for tba parcapt.
Banca, Koffka coaaldarad apparant notion a glwan, not a laamad, fact.
Koffka want furtbar, bowawar. 8a presentad bis with tba dota la
exactly tba sana poaitloa aa bafora, but without tba parlaphara. Tbla
tine tha percept was of a aarlaa of dota junplug about; they no longer
rolled enoethly fren one position to tba next. Ha interpretad bis
findings aa nsanlag perception la a function of tba entire field, and
not af one part of tha field without consideration of tba reminder.
These experlnsnts show without question that theca era definite
effects upon tba perception of apparant notion of tba changes in tba
ground against which tba figure la seen. Tbla baa, af course, bean
known a long tine la tba studies of perception of static fields. Barly
investigations noted that sons figure properties in fans perception of
apparently mvlag objects ware influential la perception. leicheaberg's
study (27) Indicates that In tha duration of perceived notion significant
dlffaroncea between all combinations of figure patterns war* not ob
tained. neither la term of nasa tina for perceived notion nor in
total tins of perceived notion of two lighted figures la notion was fora
s significant variable. In an analysis of naan tins for perception of
one lighted figure in notion, e.g., optIns1 nvenset, fora was signifi
cant In tba £ test. Aa F test for analysis of variance of total tine
of perceived notion was not significant. Thus, figura Is laportaat la
sons nsasurensats of apparent notion but not in all.


12
arranganent presented by Chat ground la visual apees, and thasa hypo*
thatleal banda ahould hava an important aCfact on tha pareaptlon of
apparant notion (2, 23).
k position for tha derivation of throa hypothaaaa baa boas
astabllahad. Tha next atap ia to daoign an experiment to taat than.
First, it nay ba antieipatad that tha non-figurad, i.a., plain, ground
ill prvida tha laaat interference with apparent notion. It will do
this because, under tha principle of lsoamrphisn, it ill consist only
of uniformly excited neurons. Because it poses no barriers to the
pareaptlon of apparent motion, it is anticipated that it will provide
tha largest flash-rate range of apparent motion. If tha upper flash-
rate threshold for apparent motion is measured, it should follow that
this value is increased: the j is able to perceive apparant motion at
a higher flash-rate before it breaks down. It should also follow that
the £ could perceive apparent motion at a lower flash-rate: tha lower
flash rate Ilmen should be decreased. The net result should be an
increase la the tangs of flash-ratas within which apparent motion may
be perceived.
Secondly, if a vertically barred ground against which apparent
motion is to be seen is used, it ia anticipated that such a ground
should form a barrier to the perception of apparant motion. In tha
cortex, under tha principle of isomorphism, it is expected that alter
nating bands of excitation and quiescence corresponding to the alternating
bands of dark and light on tha ground would be set up. Since a horl-
sontally moving light is produced in the apparent notion apparatus,
this naans that the band of excitation set up by such e percept ia


3a
Another finding of iaportaac* mm Che consistency of |Wttd
effects for the Measures of Koto Motion. Tbs Pearson product Monsut
correlation coefficients were significant. Per several Measures,
except for certain ground effects on optinal rate, the obtained || he tesen
the non figured and vertically barred ground, and be tunea the eettieallp
and herlseatally barred grounds ewe significant beyond the 1 per cant
level of confidence. Only the correlation bateesn the non*figured and
the horieootally herrad ground* for optinal flash-rate mm not signifi
cant statistically. Moreover, the highest £ mm obtained at the lover
threshold. Xt any he interpreted as indicating that the Os mot* soot con
sistent at the lover threshold. These Os Mere not consistent st the
optianl flash-rats as*sure.
Xt uould sppnar, then, on the basis of thoM resulta, that a
flash-rata uuat have s certain Mialreea to he perceived aa appnrest
notion under the p*roasters that heve been used in thin study. The
very high consistency ef the j'e report et the lover threshold anpha-
eised (for nest Of) the constant property of this nUlaunu These
grounds have no inportant effect oe the loner threshold. On title heels,
it sesos aost reasonable that one should leek for s physiological rather
than a perceptual explanation to understand this portion of the
pheoonenon (1).
la constructing a physiological nodal to account for thin port
of the findings, aa faypothMis of o sonnet ion ef neural iapulaoa taking
placa in the cerebral cortex vas assuasd. On the basis of available
evidence this sean* a safe aeeunptloa (2, 23), Von, uben the aye is


I
equally to the neural finida of tha cantral nervous ijntia aa noil ao
the parcaptual fiald. Tha antira Mosaic, than, from tha axe amal
stimulus field through tba rscaptora, tha cortlcopatal nschaalsns, and
tba cortex itself, all anear into tba final perception: these together
constitute tht functional Mhola.
The effect of the ground upon the perception of flgureo con
tained within that ground haa had a long history in psychology, hut baa
been explored met extensively by the Gestalt writers (6). garly work
Included Chat of Rubin (28), Gottachaldt (10, 11), and Koffka (Id, 17),
In general, Rubin worked upon the effects in perception of the re
versible figure-ground illusions. Gottecheldt did noet of bin work
witk coaces loan t of figure la ground. These effects ware all in static
fields, however. Koffka dealt sure with the effect of ground in
dynonic fields, aa in the perception of apparent notion. We will
detail two approaches hare: that of Duncker (5) and one of Koffka'a
(Id) which deal with tbs dynonic field percepts.
Duncker'a work dealt with induced notion: the perception of
notion produced in one figure by the notion of another in the field,
end the notion produced in the figure by the notion of the field against
which it wee seen. In hie experiment, he exposed successively by neons
ef s tsehistoscope two rectangles with dots placed upon than. The dots
alone ware superimposed in successive presentations, first in one sad
then la s second rectangle. In another series of experiaeats,
neither the dote nor tho rectangles were superimposed. Hie finding*
indicated that the fixated figura nee tha norm susceptible to tba induction
ef notion, the enclosed, rather then the enclosing figure, showed the


3
Inner (7) proposed la 1173 retinal asura1 theory to account
for both real aad apparent motion. Zt involved the interaction betunan
elements in tbs retinae when the elements mere successively stimulated.
This interaction served to smooth into one continuous percept the stimu
lation of the series of discrete points in the retinae. However, the
finding that apparent motion took place aben one stimulus urns presented
to one eye aad another stimulus to the other eye effectively vitiated
this theory, for there could not possibly be any retinal neural inter
action under these conditions (3, 31). Wertheimer (34) proposed the
next step in a modification of laser's theory. He placed the accessary
Interaction centrally, in the cerebral cortex, rather than peripherally,
in the retinae.
There have been a number of experiments performed using only one
eye, using both eyes together, and using both eyes separately (3, 31).
These aimed at substantiating or refuting the neural interaction theories.
Xf both stimulus lights are presented binoculariy, then interaction of
the generated neural fields could take place at any point along the
visual corticopetel pathways; the retinae, the optic chiasms, the
lateral geniculate nuclei, the optic radiations, or the striate cortex
(Irodmana's area 17), or even in the mora cenote subcortical structures
(23, 32). Similarly, the presence of the stimulus lights in one eye
would rule out one-half of the peripheral neural system, but would not
rule out any of the more central structures because of the hsmidecus-
ation of the optic tract at ths level of the optic chiasma. But by
presenting one light to one eye, and another light to the other eye,
only ths central structures could be involved in the neural interaction (37).


40
nauta through tha post-synaptic neuron, and thus firs it. It uw
probable that this for of summation (spatial) ia the visual system
paratas to provide a smooth, filled*ia projection of the external
stimulus field, hile the first, temporal summation, operates to provide
a smooth, continuous percept of real nation ia tha external stimulus
field.
Is this model, se tha stimulus lights for Bets motion are
driven at a vary low flash-rate, a.g., about 1 f/s, a nave of excitados
is sat up in tha retinae Cor each flash of each light* This, ia tun,
fires the succeeding corticopetal neurons, and the impulse eventually
ends on tha cortical neurona. Bat there is also a series of impulses
sat up which impinge on tha dendrites of the adjacent cortical aeurone
in tbs visual striata area. With such a low rata of flashing, these da
eat form tha sequence apparently needed for aumsatioe to taka place} ear
ace tha two stimulus lights dose enough together spatially so that the
impulses aroused by tha stimulation of tha retina impinge on the same
iaterauncial neurone. 4a tha flash-rate increased, tha impingamaat of
these impulses oa adjacent neurons becomes more and more frequent}
finally, a rate is reached which allows taaporal summation to taka
place. Then tbs area of stimulation ia spread a little, sad other
seta of internuncial aeurone begin to be given some subthreshold stimu
lation. Be the flash-rate is further increased, the seme merhenlsm in
volves more end more neurone. 4 locus of excitation is get up. 4a this
locos is enlarged with increasing flash-rate, it may begin to interact
with the locus which bee been eat up by the stimulating of the eacoad


2
per second (A M| offi A off, 1 on), tte duration of tte pause, if anp,
bttwu A and B, lateasitp of tho atlaulus light a, duration of tho
flatten, aaasuat of dark adaptation prior to tte presentation of tte
licita, diatanca betunen tte lighta, iaatructiooa to tte j, laagth of
tte praaaatatioaa, praaanca of figuvaa includad on tte faca of tte
atiaulua lighta, and tte background havo all bona shown to ba iaportant
variables <1, 2, IB, 34, 37).
Tte ralatioaabip of panno tiaa botnoaa tte ligbta, intoneitp, and
opatial aoparation ora furtter invoatigatad bp torta (It). Tte fotacl
statenant ia kaow an torta'a Lawn, although aoaa of bin findlaga tena
racantlp tean quaatloaad (6). torta found that a abort tiaa la tamal
batucan tte two oxpoauraa, a long diatanco batucan tte atiaulua ligbta,
and a low la tana it p of atiaulua ligbta ando perception of tte ptenonaoon
difficult. Ho one of thane conditlona acta in itself} ratter, there ia
an iaportant interaction betunen tte uariabloa. Corbin (4) abound in
hla aaparlaaata that a long diatanco tetween tte ligbta can ba bridged
bp a long pauaa tiaa.
There have boon a atiabar of theoriaa attempting to explain
apparent action. Aaoag tte earl lent of tbaao una tte epe-aovoaant
tbaorp which atetad that the aoveaant of tte apea and their auaculature
accounted for tte perception of tte notion. However, Guilford and
Halcn (12) abound that there uea no aigniflcant correlation betunan
tte reporta of apparent notion and tte photographic record of epe aova*
anata during tte report. Wendt (35) abound that during tte perception
of apparent notion, tte apea ware engaged la fixating objacta juat aa ia
tte perception of coal aoveaant.


l
illuminate tbt ground*. The** ground* unen aclosed In a heavy card
board fraa*. th* ground* wens all 26.1 en. by 31.9 ca. subtending
10.2 vortical and 13.0 boriaontal viaual angla* at on* au Croat tb* 0.
Tba*a ground* oro mounted in a alid* in tb* front of a light
tight box vhieh contained, in addition to th* K113CB tuba* and tboir
laa* ays tan* and aportar**, a 26.8 on. by 31.9 cm. ground-glass dif
fusing croon and too 13 uatt incandescent bulba, rod in color and
tubular in shop*, which wars noun tod vertically on each aid* of th*
croan. The bright**** of th* ground illumination an* controlled by
varying tb* voltage across the tubular lamp* by asan* of a Variac trans
formar. The vo1tag* an* maintained at 12 volts (v.) throughout the study.
Th* illumination an* rad for the ground* in ord*r to maintain tha O'*
dash adaptation at a atabla level (29 39).
Tb* antis* light penal, tha ground support, and tha O'* chin
rust aura inclosed in a light-tight tunnel mounted on an optical banch.
Tb* dUtanca from tb* light panel to tha £' chin vast ana maintained
at orna m. A block diagram of th* light panel is shown in Fig. 1.
Tha optical bench, th* £' booth, and tha aatlro room war* all
paintaw flat black to absorb light. Considsrabla car* an* taken to
prevent light leakage from tha £' boothnecessarily illuminated in
the course of th* experimentor from external source*. Leakage would
naturally vary tha adaptation level of th* £ during the course of th*
experiment. It should ba noted, however, that the naan duration of
notion perceived during parlad* longer than 4 min. of dark adaptation
is relatively constant (3§) and mean duration is not significantly
changed by change* in illumination within th* rang* need (30). 4


CHAPTER II
AmiATOS km PROCEDURE
toBMESHI
Tte apparatus dividas into tha followingj the alactcoalc switch,
tbs stlaulus lights sad grounds, and tha recording eguipaent.
IMftJSftteB maiHg -ThU part of tha apparatus consisted of
an electronic switch controlling two gylvenia Ell 1301 electronic glow
tubes, tha stlaulus light sources. The switch used was described by
Saucer (30). It la a wide-hand, high-gain pentode r-f amplifier in a

multivibrator circuit. Tha gating signals produced are aguare, having
a negligible rise and decay tine. Cathode coupling is used to tha
K1130S tubes to preserve this wave-fora. The circuit la stable to 15
kilocycles (kc); it la no really operated wall within thia sargia.
Several flash-rata rangas are provided in tha control switch, giving
rates free 0.2 flashes per second (f/a) to 30.5 f/a.
Tha second portion of tha apparatus included tha stlaulus
lights, tha equlpaeat used to support and llluaiaate tha grounds, tha
Ions associated with tha 111300 tubes, and the diffusing screens. Tha
Sylvsala 111308 glow tubes provide a sharp response up to tha ioni
sation value of the tubs which la approximately 15 kc. The actual
decay and risa tina of tha light stlaulus la on tha order of 2 to 3 nieto*
sac. The light output of the tube varies linearly aa tha plate current.
1*


41
stimulus light. Finally, the two loci in tha usual cortas iataract
through a "bead el neurons batwaaa than, and no loogar diacraCa point#
ara praaant. Tha parcapt under thaaa condition# nay ha al a ringla
light which wing# hack and forth, following in it# trajectory tha hand
oi stimulation which haa been canead by tha interaction of the loci eat
up by each light.
Thia neural iy oriented explanation seams to lit tha facta ob
tained in thia study for tha lower flash-rate threshold. It la con
sonant with tha Hading of tha highest correlation coefficients at tha
loara flash-rate threshold. After all, tha nervous ays ten does asee
to have rather stable ties constants under which auenation can take
place (23). The interpretation appears to be in agraanenf with tha
analyses of variance and the J test findings, both of which show that
there is no significant difference for ground at tha lower flash-rate
threshold; it is flash-rate which is the important paran#ter, and not
tha patterning of tha grounds through which the Beta ration takes place.
It is, than, a neural, rat a perceptual, phenomenon which takes place
at the lower threshold.
On tha upper limit of apparent notion there are statistically
significant differences in tha naans of tha motion seen against the
fixed grounds used In this study. These differences are in each case
between tha figured and the son-figured grounds. In coopering directly
tha obtained means for this mensura of apparent ration, it was found
that rare ration was seen on tha non-figured as coopered to tha figured
grounds. it was earlier hypothesised that thia might taka place on tha


ACKNOWLEDGMENTS
The writer wishes to express hie sincerest appreciation to the
Chairman of the Supervisory Comnittee, Dr. K. P. Home. He wee ee
unfailing source of inspiration and a critical person in the fomotive
stages, and gave unstintiagly of his tine, knowledge, and patience in
guiding the course of this study.
Many thanks are due the members of the Supervisory Connittee,
Drs. A. M. Barrett, J. C. Dima, W. W. Bhnsatm, t. D. Hinckley, and
H. B. Webb.
Thanks are also due the many persons who served as subjects for
this experiment.
ii


20
Of necessity, the instructions wn miad in content for Mch
g, for hm wn oro miliar than otilara with tba phenomenon. In 11
casas, tha asaantial Aullaban ara conatant. Moca aecusaca multa
aaca obtained by equalising tba practica affacta among j{, Each j aaa
alionad to become thoroughly familiar with tha charactariatica of Bata
motion at each flash-rate. Although tha content of tha iaatructiona
aaa variad with thaaa 0a, tha iaatructiona aaca dealgned to iaatill a
aiailar Kinatalluna la each g. Following thia period tha aapacimoatal
observation began.
Of ware assigned to a Oraaco-Latin Square in seriatim order (19).
(Sea Appendix A.) Although Gilbert (9) had shown practice may ha of
soma importance in tha perception of apparent motion a more meant
study by fteichenberg (27) indicated that mean duration of notion ana
not significantly different during three successiva practica periods.
However, the use of thia type of experimental design provides a control
of thia variable, since each ground was presented in each ordered position
an equal number of tinea.
Tha uaa of this experimental design also provided tha schedule
for tha presentation of all grounds to tha Of. Tha presentation of
each ground then was of a descending and ascending aeries of nine flash
rates. These rates warn 0.4, 1.5, 2.5, 3.5, 4.5, 5.5, 4.5, 7.5, and
8.5 f/a. Tha uaa of counterbalanced series was designed to preclude
any systematic error on the pert of the 0 due to anticipation or
perseveration (39). All gg warn given thane aeries for each ground.
Thus, g observed n total of 18 periods for each ground, or a total of 54


30
TABU 3
ANALYSIS Of VAR1AUCX FOR VAAIABLSS MODIFY UK LOUSE
FLASH"RATS THRESHOLD: GROUNDS X ORDER Of
RE MORAY IDE X REPLICATIONS
Soutea
so
df
Z
ratio
1
X
Grounds (6)
0.07
2
0.04
"6'SR
.36
*
Ordor of Prsooatatlon (0)
1.54
2
0.77
aso/asgt
60
so
Replications (E)
6.30
11
0.57
so
s>
so
G X 0
0.37
4
0.09
*cc'-*oo*
60
m
X ft
2.47
22
0.11
so
m
*
0 X ft
28.35
22
1.29
4*
m
-
G X 0 X ft
6.78
44
0.15
m
so
49
Vitkin Calls
0.00
0
m
m
m
SO
Total
45.88 107


29
variance of Che muuim. According to the wyriuntal design um4,
the significance of the offacts could bo evaluated for throo sources:
tbs grounds, tbs order of presentation, sod tbs double interaction of
tbs grounds sad order of presentation* The assures, loser three bold,
upper tbreeheld, optinsl rats, and range of rates vithin which Beta
notion was seen, wars all designated as dependent variables; each
assure provided s separate analysis of variance. Ground end order
of presentation, two of the three dInanetons, ware fined variables*
The third variate waa a ran don variable, replication* This type of
design peralte the evaluation of the grounds, of the order of pre
sentation of the grounds (practice), and ef the lateaction of these
two* Evaluation of individual differences is aot obtainable. it was
assumed that individual differences would be readonly distributed and
would there fora aot neks an important contribution to tbs variance fa
this design* Since theca waa only one individual assigned to each call
under this arparlaaatal design, within call variases was acre.
The first of these analyses, that of tbs lower threshold by
grounds by order of presentation by replications, is presentad in Table 3*
It is evident that there wars as statistically significant sources of
variance between tbs variables* It nay be concluded that ground was
not s significant variable in tbs determination of Bote notion for the
assures used at the loner threshold*
Xt should else be noted that there wars ns statistically signi
ficant practice effects (order sf presentation). The control of
practice effects by assignment of Os in a seriatim arder to a Graeco-
Latin Square waa affective.


uniucKS
1. tartUy, 8. H. The relation of rocinal illumination to the
experience of movement. J. Bxner. fwchol., 1936, 1, 475*415.
2. Sortlay, 8. 8. Vision. A Study of It Baal. Haw York: Van
Hostrand, 1941,
3. Brown, J. V. Thresholds for vlaual movement. Psychol. Forach..
1931, 14. 249-248.
4. Corbin, 8, 8. Iba perception of grouping la apparent movement In
vlaual depth. ..ftggtoj,,, Jj. Y., Ho. 273.
9
5. Duncker, 8. Ubar indusiarta Bewegnung (Bin Beltrag aur Theorle
optinch Hahrgeaomnsner Bewegnung). Psychol. Forach.. 1929, \2,
180-259.
8.Billa, 8. 0. A Source Book of Geatalt Peycholonv. Hew York:
Harcourc, Brace, 1935.
7. Bxner, 8. Kxparimentelle Unterauebungen dar alafaackaan payebiaeban
Procesas. XII: Abbundluag: Oar peraonllchan Gleichung swelter
theil. £|iu8,,^rcA.^ga. Physiol., 1875. U. 403-432.
8. Gangarelll, J. 4. Apparent nmniat In relation to homonymous and
heteronymous stimulation of the cerebral hemispheres. J. Barer.
Psychol.. 1948, ft, 592-599.
9. Gilbert, G. M. Dynamic psychophyaice and the phi phenomenon.
Arch, Fayebo1. H. Y., Ho. 237.
10. Oottaebaldt, K. I: Ubar dan Binflase dar Brfahrung auf die
Vahrnabmuag von Figuran. Faychol. Forach.. 1924, 8, 261-317.
11. Gottschaldt, K. 11: Uber dan Binfluaa dar Brfahrung auf die
Wahrnehmwng von Figuren. Faychol. Forach.. 1929, 1, 1-87.
12. Guilford, J. F. and Unison, a. Bye movements and the phi-
phenomenon. Am. J, Faychol.. 1929, 595-606.
13. Hartmann, 0. 8. gestalt. Psychologic jugaz^of. Fagta and
Principias. Haw York: Ronald, 1935. Fp. 23-30; 125-126.
14. Hartmann, L. Beue Varacfamalauagaproblema. Favchol. Forach..
1923, 2, 319-396.
46


THE EFFECT OF CHANGES IN CERTAIN
DETERMINANTS OF GROUND UPON THE
PERCEPTION OF BETA MOTION
By
HERBERT CARLTON HART
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
January, 1959


9
It the figures are different la tom or la color, this differ
ence any bacons ea iaportant variable la the percept loa of apparent
aotioa. Orlanaky (29) explored these variables. He tom that If
the stloulue lights ere eboea la the fore of too arrows pointing la the
sene direction, aotioa Is easily seen by aoet Of; It is quite cea
palling, end Is very realistic, but if one arrow palate to the right
end the other to the left, It becoaes auch aere difficult to perceive
apparent aotioa, and It is easily lost. More tlae oust be allowed
between flashes (l.e., by increasing tbs pause tlae er by decreasing
tbs flesh rate) if apparent aotioa Is to be seen. Ivea so, a coa-
side reble aunber of Of cannot obtain good aotioa under these conditions.
Kills (t) explains this phsnonsnon under the headings of pteoasns end
of coanon destiny. Belcheaberg (26, 27) carried out on additional
study la this erne. His findings la general confined those of
Orloasky although he used very different stlaulus figures.
The phsooasnoa of epperene notion Is not Halted entirely to
the use of alternate lighted areas, although this node of presentation
has been the aost manna la the pest (33). brown (3) found that e
similar phenoaanon was obtained In the perception of reel aotioa under
certain conditions. brown used a continuous strip of paper to which
black rectangles bed been applied, and varied the speed of rectangles
aovlag pest e slot. A aesk concealed the remainder of the strip.
The g observed the no vacant. When the paper wee aovlag at a high rate
of speed past the slot, the rectangles were perceived as a continuous
bend of gray. At low spesds, the rectangles were reported as saving


LUX OF ILLUSTRATIONS
Figure feg
i* Block Diogroe of the Light Proel ......... 17
2. Block DUftaa of the Exporlaontel Boom
It
V


This dissertation ss prepared under the direction of the
chaimea of the Supervisory Couartttee end has been approved by ail
nsabers of the coasdttee. It nee outwitted to the Dean of the College
of Arts end Sciences and to the Graduate Council end wee approved as
partial fulfillnsat of the requirenents for the degree Doctor of
Philosophy.
January 31, 1959
Dean, College of Arts end Sciences
Dean, Graduate School
SUPERVISORY COMMUTES:
t L.\4^tu
2/(J/ /(/ *7*
^0^ /S*


TABLE 7
SKX1FXCASCI OF TIB DIFFKIMCKS BKTWKIB TIB HUBS OF
TIB MEASURES OF BITA MOTXOR
Ground
Vertical
Ground
Horiaontal
Ground
. r j *i i'i y,
Loner Flast-rate Threshold
Mon-figured
2.14**
1.33
Vertical
*
0.71
Optlasl Flash-rate
Hoa-figured
1.87
0.50
Vertical
m
1.08
Upper Flash-rate Threshold
Son-figured
3.02*
2.78*
Vertical
m
0.26
Benge of Motion
Mm-figured
3.02*
2.48**
Vertical
0.46
Significant it the 0.01 lml of confidence, df Z 36.
Significant at Cbe 0.05 level of confidence, df 3 36.


TABLE OF CORREIS
*
ti
LUI OF TABLES tv
LUI OF ILLOSIBATZOMS V
Chapear
Z. INTRODUCTION . . 1
IX. APfABATUB AND PROCEDURE U
Z1I. RESULTS 22
rr. discussion aid conclusions 37
V. SUMMARY ........ ....... 43
AF1UDXX AS
REFERENCES 46
1U


39
presented with two alternating stimulus Lights forming the basis tor
lots wtiM, tbs light from sach of thsss Lights falling oo tbs ratios
gsnsrates a neural impulse which is thao tranmnittsd along the visual
pathways to the visual cortex, osar Brodnann's area J (23). Tbs
evidence indicates that each tins the light flashes, a traia of corti-
copetal neural iwpulsea is generated, and presumably ends in the
visual cortex. According to L. da go's (23) statistical nodal of the
visual pathways, these Inpulses nay bs retained in discreta pathways by
the processes of mention and inhibition. The nodal aeannes that a
relatively strong lapulea is necessary to fire a post-synaptic, eorti-
copetal neuron; this strength of impulsa any be called the "norma 1" one.
The neural net ef the retinae and cortex ace connected by a series of
neurons. A weak impulse, radiating along these branches, nay not have
the atreagth necessary to fire nova than one, directly connected post-
synaptic neuron. A neuron barely discharging above threshold although
impinging on ethers nay not fire then. This processing serves to pre
serve the discrete nature of the original stimulus object*
However, the nodal assumes both temporal and spatial sunaatiee.
The first assumption states that, for two neural impulses discharging
ea a post-synaptic neuron's dendrites la a particular temporal order,
end neither of which ate in thanoelveo ef sufficient intensity to fice
the poet-synaptic neuron, a si men t Inn nay produce a supra threshold
intensity and fire tbs neuron. Tbs aecoad assumption of spatial
summation states that given two subthreshold impulses which arrive on
separate dendrites ef tbs poet-synaptic neuron at the sans tine, nay


17
-

-- T~y 7 V -
-- v_y =
-
A R1130B Stimulus Light
B Ground (Horizontally Barred
Ground Illustrated)
C Light Panel Support
D Optic Bench
E Chin Rest
Fig. 1.--Block Diagram of the Light Panel
OB >