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


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The effect of changes in certain determinants of ground upon the perception of Beta motion
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v, 48 leaves : ill. ; 28 cm.
Hart, Herbert Carlton, 1926-
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Subjects / Keywords:
Movement, Psychology   ( lcsh )
Perception   ( lcsh )
Motion   ( lcsh )
Psychology thesis Ph. D   ( lcsh )
Dissertations, Academic -- Psychology -- UF   ( lcsh )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )


Thesis--University of Florida.
Bibliography: leaves 46-48.
Additional Physical Form:
Also available online.
Statement of Responsibility:
by Herbert Carlton Hart.
General Note:
Manuscript copy.
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University of Florida
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All applicable rights reserved by the source institution and holding location.
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aleph - 022282653
oclc - 13621271
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Full Text






January, 1959


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





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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



1. Block DLiarpmof th LLght Pfual .

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



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


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

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




1.-- --



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


. -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




Legend: A

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





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:


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


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


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

waxer or t oassvtwna

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

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 -


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

0o]DiL rIMU-5AM : GOom I OR= o

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

Groumad (a)

O1l.t1 of ?wa tatou

m0, Lust am

a x 0

* X 0

*J X X ft

vlitbin Calls










2 O.?o ,/m









0.03 moo/sn 0.02

1.07 0

O.4 o 0,-1

1.63 ,
0.4 maom, 0.4


* a a





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


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 *




w02=1 ov MUIT IOU I taUJUIVU

*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


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.


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




















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

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

caPrn iv


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

AMoter ftIftl of iptnumoe me the comusiltcy of Smund

effects for the msures of Beta motieso TIMhe Pest"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


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.


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


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.



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.

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.


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, ,

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.


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;

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,

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.


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


January 31, 1959

Dean Colle of Arts sad sciences

Dean, Graduate ScheoL



..... _4 ^ ^ ^ ? i .A __

t ItI/ f^ I^^ -~~c tt