Title: Psychophysical method and phoria as variables determining apparent movement
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Title: Psychophysical method and phoria as variables determining apparent movement
Physical Description: iv, 28 leaves. : illus. ; 28 cm.
Language: English
Creator: Rusnak, Alan Wais, 1937-
Publication Date: 1964
Copyright Date: 1964
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Subject: Perception   ( lcsh )
Motion   ( lcsh )
Psychology thesis Ph. D   ( lcsh )
Dissertations, Academic -- Psychology -- UF   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
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Thesis: Thesis -- University of Florida.
Bibliography: Bibliography: leaves 26-27.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
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Bibliographic ID: UF00097942
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: alephbibnum - 000574221
oclc - 13841695
notis - ADA1584

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PSYCHOPHYSICAL METHOD AND PHORIA

AS VARIABLES DETERMINING

APPARENT MOVEMENT











By
ALAN WAIS RUSNAK


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


April. 1964















ACKILOWLEDGC.ENTS


The writer wishes to express his appreciation to the many

people who have contributed to the preparation of this dissertation.

Thanks are due to Dr. M. E. Shau, Dr. J. C. Dixon, Dr. A.

Schunacher, and Dr. G. R. Bartlett, members of the supervisory committee,

for the guidance and interest they have shown.

The writer would particularly like to express his gratitude

and appreciation to Dr. E. P. Home, chairman of the supervisory

committee, for his consultation, effort, support, and guidance in

making this dissertation a reality.

Thanks are also due to Dr. A. E. Brandt of the University Com-

puting Center for his consultation on the statistical procedures in

this paper.

















TABLE OF CONTENTS




Page

ACKNOWLEDGIENTS . . . . . . . . ... .... ii

LIST OF TABLES . . . . . . . .... . . iv

CHAPTER

I. IT ODUCTIO . . . . . . . . . 1

II. ETOD . . . . . . . . . . . 6

Design . . . . . . . . .. .. 6
Subjects . . . . . . . . . .




V. S Apparatus . .COC . . . . . . . 21
Procedure . . . . . . . . . . 10

III. RESULTS . . . . . . . . . . . 12

IV. DISCUSSION . . . . . . . . . . 17

V. SU:IHARY AND CONCLUSIONS . . . . . . . 21

APPENDIX . . . . . . . . .. . . . . 23

REFEPRSECES . . .. . . .. .. . . . 26

BIOGRAPHICAL SKETCH . . . . . . . . ... 28



















iii
















LIST OF TABLES


Table Page

1. Sumnary of Analysis of Variance for iale Data . . 13

2. Summary of Analysis of Variance for Female Data . . 16

3. Central Tendency and Variability for Hales . . . 24

4. Central Tendency and Variability for Fenales . . 25















CHAPTER I


INTRODUCTION



The purpose of this study is to examine the effects of psycho-

physical method, variables of phoria, and their interactions on the

perception of apparent motion. The specific type of apparent notion

to be utilized is called beta notion. Beta motion is defined as the

perception of short lateral movement when two intermittently illuminated

objects are presented in succession.

The phenomenon of apparent notion has played a controversial

role in some theories of perception. It is differentiated from the

perception of real movement in that the perception of real movement

involves the physical movement of a stimulus object over a given period

of time. Apparent motion is that which is perceived when there is

actually no moving stimulus in the visual field.

Experimental and theoretical work in the area of the perception

of motion was done by Purkinje as early as 1820 (Boring, 1942). In

1870 Dvorak (Boring, 1942) hypothesized that the perception of motion

was dependent on the simple interaction of neurons in the retina.

Following this, Exner (Neff, 1936) maintained Dvorak's notions of

retinal interaction processes, but extended them to state that the inter-

actions can also involve areas of the retina not immediately adjacent

to one another.









The major contribution to contemporary theories of perception

regarding notion was made by Wertheiner (1912). At that time he pro-

duced irhat he called pure movement or phi movement without the

succession of stimuli. On the basis of his findings he discarded the

notion that perceived movement was dependent on simple retinal pro-

cesses alone and posited a cortical interactive or integrative process

as the physiological substrate of notion perception. A study by

Gengerelli (1940) supported Wertheimer's theoretical formulation.

Wertheimer, and those who followed him in the Gestalt school,

also rejected the previous notions that perceptions could be broken

down into minute or microscopic physiological processes resulting in

specific sensations. They concluded that the perception of motion,

real or apparent, was a unitary phenomenon which could not be broken

doun into simpler analyzable constituents (Ilelson, 1925). The Gestalt-

ists have insisted that perception is not completely tied to the sepa-

rate physical characteristics of the external world. They propose that

there is an organizational characteristic which is imposed on sensory

input by the processes of the perceptual system. In a recent form

(Klhler, 1958) Gestalt theory presupposes that the more important cor-

tical correlates of perceptual experience are electrical brain currents

rather than neural impulses.

Kenkel (1913) described three types of apparent motion in addi-

tion to Wertheimer's phi. Of these, beta motion has received the

greatest amount of experimental attention. Neff (1936) distinguishes

two classes of experimental variables connected with apparent motion

perception: intre-organic variables and extra-organic variables.

Subsumed under intro-organic variables are dark adaptation, instruction,









past experience, attention, and attitude. Saucer (1950) and Uilson

(1957), in independent studies, found dark adaptation to be a signifi-

cant variable in perception of apparent notion. With regard to the

other intra-organic variables there is little conclusive evidence.

Reichenberg (1957) found instruction to be conditionally effective as

an experimental variable. Under extra-organic variables Neff (1936)

cites interval between successive presentations of the stimuli, inten-

sity of the stimuli, exposure time of the stimuli, and similarity of

form of the stimuli.

Korte (Ieff, 1936) formulated a set of laws relating the variables

of interval between stimuli, stimulus intensity and distance between

stimuli. Although Korte's laws hold up well within certain limits,

they have been shown to break down at the extremes of the dimensions.

Orlansky (1940) and Reichenberg (1957) have studied the effects

of similarity and difference between stimulus forms and have found that

similar forms facilitate apparent motion.

Flash rate (Saucer, 1954; Lane and Home, In Press; Home and

Deabler, 1962) has also been studied and has been found to be an impor-

tant variable in apparent motion.

Research findings by lotokawa (1953) have been interpreted to

indicate that retinal responses during the perception of real and

apparent motion are identical. This finding lends additional support

to the Gestaltist's contention that motion perception is dependent on

a cortical interactive or integrative mechanism.

Following this, it may be proposed that interference with an

observer's normal approach in perceiving his environment will result in

a disruption of the integrative process and a disruption of the ability









to perceive apparent motion.

Part of this study is concerned with an investigation of the

effect of varying normal visual processes on the perception of appar-

ent motion. This is to be accomplished by the means of experimentally

inducing dysphoria in "normal" subjects.

A second part of this study is concerned with the effects of

psychophysical method on the ability to perceive apparent motion. It

may be predicted that the method of serial exploration would yield a

predictable shift in the upper limit of apparent notion. This assum-p-

tion is made on the grounds that with an ascending series of change in

phoria, the method of serial exploration (limits) permits series effects

(habituation of movement) to become operable, extending the range of

movement upward in pulse rate. With the method of constant stimuli,

habituation would not be systematically introduced although a randomly

ordered, discrete set of phoric changes, adjusting for convergence, might

also have a systematic effect on the upper limit.

The following specific hypotheses are to be investigated in this

study:


1. Experimentally induced dysphoria may disrupt an observer's per-

ception of apparent motion. This effect will be shown in de-

creased mean durations of perceived motion as the artificially

induced dysphoria becomes progressively more severe. An increase

in phoric imbalance, or dysphoria, will produce a decrease in

mean duration of perceived apparent motion.


2. For a horizontal direction of movement a condition of horizontal

dysphoria may be more disruptive to the perception of apparent





5


notion than t~ill a condition of vertical dysphoria. This will

be shown by greater mean durations of perceived apparent motion

for the condition of vertical orientation of dysphoria than for

the condition of horizontal dysphoria.


3. The psychophysical method of serial exploration may extend the

range, thereby raising the upper threshold of apparent notion.

The method of constant stimuli is to be used as a comparison

method.















CHAPTT.:? IT


iETiIOD



Design

The independent variables to be examined in this study were

psychophysical method [method of serial exploration (Cl) and method of

constant stimuli (C2)], horizontal (Bl) and vertical (B2) orientation

of dysphoria, and degree of dysphoria (A). The dependent variables

were: (1) the number of key presses made by a subject during an

observation, and (2) the duration of perceived movement which was

recorded on tape. The first variable was, therefore, the number of

times motion was perceive during a trial. The second was the length

of time motion was perceived at each occurrence, and from these variables

the mean duration of apparent motion was obtained.

The design of the study was such that all subjects received all

treatment combinations (ABC) in the same order of presentation for each

of the two psychophysical methods. One major treatment variable was

the effect of the psychophysical method, i.e., the constant stimulus

method and the method of serial exploration. In each method all subjects

received two directional dysphoric effects, horizontal and vertical.

Clinically, dysphoria is a condition in which a person is unable

binocularly to fixate a given point so as to produce a single visual

image. Symptomatically, dysphoria is generally described as double vision.









In ophthalmological terms, the particular condition of horizontal

dysphoria used in this study is called esophoria (an excessive con-

vergence of one eye towards the other, or "crossed" eyes). The

ophthalmological term fcr the vertical orientation of dysphoria is

hyperphoria, a condition in which one eye diverges vertically From the

line of sight of the other. Under each directional condition, hori-

zontal and vertical, all the subjects received varying degrees of

dysphoria, with the rotary prism set from zero to 28 prins diopters.

These degrees of dysphoria were experimentally, i.e., optically, pro-

duced by adjusting only one (left) of the two rotary prisms of an AO

phorometer. The AO phorometer and its method of use in this study is

described below. Under the method of constant stimuli the phorometer

settings determining the degree of dysphoria were varied by a randomly

selected order which was unchanged for each of the 50 subjects. Under

the serial exploration method the degree of dysphoria was increased in

eight ascending steps of four diopters from zero to 28 prism diopters.

For any single observation the combination of A, B, C variables

was complete. Every level of one variable was combined with all

levels of the other two variables. Each subject completed 32 observa-

tions. For a total of 50 subjects there were 1600 measurements of the

obtained dependent variable, mean duration.

All subjects received the method of constant stimuli (C2) first

and, in order the horizontal (Bl) and then the vertical (B2) series.

For this order of presentation (00, 24, 08, 20, 16, 28, 04, 12 prism

diopters), consecutive settings were not progressively increasing in

magnitude.









Then each subject observed under the method of serial explora-

tion (CO) for the eight graduated settings of horizontal and vertical

dysphoria. Under this method these dioptric settings were ordered in

an ascending series from zero to 28 diopters. For each consecutive

trial the setting was increased by four diopters.

The following experimental conditions were held constant:

1. rate of alternation (2.7 alternations per sec.)

2. center-to-center distance between stimulus figures (6.5 en.).

3. luminance level (0.4487 foot lamberts)

4. distance between subject and stimulus figure (76.5 cm.)

5. binocular viewing

6. the illuminated circular stimulus figures

7. length of viewing time (27 sec. per trial)


The geometric form of the stimulus figures and the pulse rate

of alternation used in this study were within optimal or near optimal

conditions for inducing the perception of apparent motion (Roichenberg,

1957).


Subjects

Fifty subjects were used in this study, 25 males and 25 females.

All subjects were students enrolled in introductory psychology courses

at the University of Florida. All subjects were "volunteers" who were

fulfilling course requirements. All subjects wearing glasses with

corrections were required to wear them during the experimental proce-

dure. Subjects ranged from 17 to 24 years of age, the mean age being

18.









Apparatus

An electronic apparatus was used which controlled the duration

and rate of visual stimuli necessary to induce the perception of appa-

rent notion. Light sources were two one-watt, neon filled, incandescent

Westinghouse Nite-Lite bulbs which alternately illuminated two separate

apertures, 6.5 cm. center-to-center and presented horizontally to the

subjects. These illuminated circular stimulus figures were 2.5 cm. in

diameter and were engraved on clear plastic with an opaque black plastic

backing so that only the engraved forms transmitted light providing an

illuminated figure. The recording units included a Gerbrands constant

speed recorder and two telegraph keys. The AO phorometer provided for

experimental variables A and B. A subject's head rest and a manually

controlled shutter completed the inventory.

The AO phorometer is characteristically used in ophthalmclogical

examinations. For purposes of this study only those portions of the

apparatus for visual phoria testing were used. The necessary apparatus

consisted of two rotary prisms mounted separately, each having a

maximum power of 30 prism diopters. Although 60 prism diopters were

available, only 30 were used so that maximal adduction was not obtained.

The prisms were situated one in front of each of the subject's eyes, in

a vertical plane which was perpendicular to the subject's line oF sight.

The prism rotation created a converging or diverging line of sight of

one of the subject's eyes with respect to the line of sight of the other

eye. Only convergence, or esophoria, was used in this study in deter-

mining the horizontal condition of dysphoria. When one or both of the

prisms were rotated 90 degrees with the "zero" horizontal, a condition

of vertical displacement of the line of sight of one eye with respect









to the other (hyperphoria) was made, thereby resulting in a condition

of vertical dysphoria. Here only an upward deviation in the line of

vision of one eye was used. Also, only the left prism was manipulated

to produce the experimental conditions for all subjects, while the

other prism was maintained in a zero position. The phororneter was

adjusted to a line-of-sight level and the head rest also adjusted to

maintain a fixed position which was comfortable for the experimental

period.

Two telegraph keys were connected to two channels of the con-

stant speed recorder. They were located so that one of them could be

operated by the subject and the other by the experimenter. The experi-

menter's key was used to record the onset and termination of each

trial, and the subject's key recorded the responses as defined.

The shutter device was opened to start a trial and was closed to

terminate it. The duration of each single trial was 27 sec. Total

viewing time for each subject was 864 sec.

The complete apparatus was housed in a light-tipht room and

illumination was maintained at a darkroom level during the experiment.


Procedure

Subjects were brought into the experimental room and seated in

front of the apparatus. Each subject was asked to place his head in

the adjusted rest. The instructions were given on the use of the key

with the shutter closed. Room lights were then turned off and the

subject was given a three-minute dark adaptation period.

Following dark adaptation the shutter was opened and the subject

was asked to describe what he saw. If he reported a perception of









motion, the shutter was again closed and the experimental procedure

begun. If the subject's renort indicated that he did not perceive

apparent motion, he -ra. excused rfro: further participation in the study.

Subjects who reported an initial perception of apparent motion

were instructed as follows: whenever r you see the lights) moving,

you are to press your key do'rn and hold it down as lonc as the lights)

appear to move. When the lights) do not appear to nove, release

your key. You are to repeat this procedure whenever the lights)

appear as though they are moving."















CHAPTER III


RESULTS



The major variables under investigation in this study were:

(1) degree of dysphoria; zero prism diopters (A1) to 28 prism diopters

(A8) in equal steps; (2) horizontal convergence-adduction test (Bl),

vertical vergence-hyperphoric infraduction test (B2); and (3) psycho-

physical method (method of constant stimuli C2 and method of serial

exploration CI). After calculation of a mean duration for each subject

the data were treated by means of analysis of variance in order to

determine, for these averages, the significance of the effects of

the main variables and their interactions.

Two separate analyses of variance were performed, one for the

data on male subjects and a second for the data on female subjects.

The analyses were carried out by IBM 709 computer at the University

Computing Center of the University of Florida.

The summary of the analysis of variance for male subjects is given

in Table 1.

Bartlett's chi-square test for homogeneity of variance in the

male sample, with 31 degrees of freedom, was found to be non-signifi-

cant, indicating that the variance in this analysis was homogeneous.

The results indicated that horizontal-vertical orientation of

dysphoria had a significant effect (p < .005) on the mean duration of














Table 1


Summary of Analysis of Variance for Male Data


Source df Sum of Squares Mean Square F p


Degree of Dysphoria (A) 7 710.5804 101.5515 1.256 NS

Orientation of
Dysphoria (B) 1 836.4056 836.4056 10.348 .005

Psychophysical
Method (C) 1 406.1250 406.1250 5.024 .05

A x B 7 543.3942 77.6277 0.960 US

A x C 7 431.7549 61.6793 0.763 NS

B x C 1 24.4994 24.4994 0.303 US

A x B x C 7 312.6601 44.6657 0.553 HS

Error 768 62,075.3730 80.8273

Total 799 65,340.7813









apparent motion reported by the iale subjects. The duration of appa-

rent motion perception was higher (15.3675 sec.) under the condition

of vertical dysphoria (hyperphoria) than under the condition (13.3225

sec.) of horizontal dysphoria (csophoria). These results supported a

second hypothesis in this study, namely that a main effect of horizon-

tal dysphoria is more disruptive to the perception of apparent motion

than a condition of vertical dysphoria.

The analysis of male subjects also indicated that psychophysical

method was a significant factor (p < .05) influencing the duration of

apparent notion reported by the male subjects. The nean duration of

perceived apparent motion under the method of constant stimuli was

15.0575 sec., while the mean duration for the method of limits (serial

exploration) was 13.6325 sec. The third hypothesis, that the psycho-

physical method of serial exploration (limits) extended the range, and

thereby enhanced a series effect,was not supported. The method of

constant stimuli resulted in greater mean duration of perceived appa-

rent motion than did the method of serial exploration for the male

subjects.

The main variable, degree of dysphoria, was not found to be

significant as an overall factor influencing the duration of apparent

motion perceived by the 25 male subjects. Variations in the severity

of artificially induced dysphoria did not significantly affect mean

duration times for the perception of apparent notion, indicating that

conditions of phoric imbalance did not significantly change the duration

of reported apparent motion.

All interactions between main variables were found to be non-

significant for the male subjects, suggesting that the main variables








under consideration nay be independent and unrelated to one another.

Table 2 illustrates the summary of the analysis of variance for

the female subjects.

Bartlett's chi-square test for homogeneity of variance in the

female group, with 31 degrees of freedom, was non-significant for this

analysis also, indicating homogeneity of variance in this analysis.

In the analysis of the female subjects' data it was found, as

with the male subjects, that the horizontal-vertical orientation of

dysphoria was a significant factor influencing the amount of reported

apparent motion (p < .01). The mean duration of perceived apparent

notion under the horizontal orientation of dysphoria was 8.2425 sec.,

while the mean duration for the vertical orientation was 9.8150 sec.

These findings again indicated that the mean duration for the percep-

tion of apparent motion was higher under the condition of vertical

dysphoria than under the condition of horizontal dysphoria, giving

additional support to the second hypothesis in this study.

The other main variables in this second analysis, degree of

dysphoria and psychophysical method, were found to be non-significant

in affecting the amount of apparent motion perceived by the female

subjects. Neither of these variables significantly affected the mean

durations of perceived apparent motion for this subject group.

All interactions between major variables were found to be non-

significant for the female subjects, indicating that the main variables

were independent and unrelated to one another in any systematic way.

Certain supplementary results in the form of statistical tables

for means and standard deviations by sex have been included in an

Appendix.














Table 2


Sumnary of Analysis of Variance for Female Data


Source df Sun of Squares Nean Square F p


Degree of Dysphoria (A) 7 G8.0087 9.7155 0.148 ITS

Orientation of
Dysphoria (B) 1 494.5513 494.5513 7.550 .01

Psychophysical
Hethod (C) 1 1.5313 1.5313 0.023 lNS

A x B 7 429.9987 61.4284 0.938 ;S

A x C 7 116.7388 16.6770 0.255 US

B x C 1 6.6612 6.6612 0.010 US

A x B x C 7 355.8887 50.8412 0.777 IS

Error 768 50,304.9639 65.5013

Total 799 51,778.3389















CHAPTER IV


DISCUSSION



Of the three major experimental variables, degree of dysphoria,

horizontal-vertical figure orientation, and psychophysical method, the

only one which significantly affected the mean duration times for the

perception of apparent motion for both males and females was horizontal

(esophoric) and vertical (hyperphoric) orientation. The second hypo-

thesis, that a horizontal (esophoric) condition of dysphoria would be

more disruptive to an observer's perception of apparent motion than

would a vertical (hyperphoric) condition, was supported.

That directional orientation of the phoric imbalance should

affect mean durations for perceived apparent motion may be accounted

for in terms of enhanced binocular imbalance in the visual field,

greater for esophoria than for hyperphoria. The human eye, with its

extrinsic musculature, is able to accommodate for more esophoric distor-

tion than it is for hyperphoric distortion. When hyperphoria is artifi-

cially induced by prismatically deviating the line of sight of one eye

from the other, it is necessary for a deviation of only two prism diop-

ters to be present before binocular visual fusion is broken with the

result that two separate and distinct images are seen. Then, as in

this study, the apparent motion was presented with the visual stimuli

effecting movement in a horizontal plane, the visual result may have









been the appearance of two moving objects (lights), one above the other.

When esophoria was induced, and the visual. stimuli moved horizontally,

overlapping visual images were produced. The overlapping movement

effects beyond a fusion limit wcre confusing a-nd disruptive '- --

ccption and naintainance of apparent notion.

The A variable, degree of dysphoria (ranging from zero to 28

prism diopters), was non-significant as a factor influencing the mean

duration of perceived apparent motion for both males and females. This

hypothesis, that an increase in phoric imbalance would produce a de-

crease in the mean duration of perceived potion, was not confirmed.

The result may be a basis for an inference that the phenomenon of beta

motion is highly stable and not readily disrupted by the manipulation

of the balancing extraocular mechanisms orienting the peripheral recep-

tors. That a peripheral interference with an observer's normal means

of perceiving his world through the introduction of varying degrees of

dysphoria did not result in decreased mean duration times for the per-

ception of apparent motion seemed to indicate some support for a

Gestalt contention that the perception of motion is dependent on the

functioning of some central integrative mechanism at a cortical level.

It was found that the subjects in this study, when faced with varying

degrees of dysphoria, continued to report apparent motion regardless

of the severity of the phoric ir.balance and that the mean duration was

not significantly reduced. Subjects may have blocked or suppressed the

sensory input from one eye in order to continue perceiving apparent

motion, thereby reporting monocular beta movement. However, even this

mechanism may be centrally organized rather than peripherally determined.

The subjects were integrating the sensory information permitting them to








continue their perception of apparent motion at a fairly stable level.

The third hypothesis, as it was stated, was not generally sup-

ported. For the female subjects, psychophysical method was found not to

be a significant variable affecting the mean duration of perceived appar-

ent motion. For the male subjects, psychophysical method was found to

have a significant effect (p < .05) on the mean duration of perceived

motion, with the greater mean duration for the method of constant

stimuli. These results were contrary to the original hypothesis, that

the method of limits would produce longer mean duration times in terms

of more habituation effect, probably extending the range of perceived

apparent motion upward. It must be noted that no rate change was

directly introduced to determine the upward extension. With this experi-

ment, the duration was investigated and there was no implication of

the elevation of the notion-no motion threshold. Only a study of

change in alternation rate may assess the upper limit directly.

The inconsistent conclusion for male and female data may indi-

cate that series effects were not "eliminated" by the constant stimulus

method but were spread by the particular sequence selected for this

application of the method.

The main effects by two analyses of variance have already been

indicated, but certain additional statistical details have also been in-

cluded in an Appendix, e.g., means and standard deviations by conditions.

The mean duration for males, disregarding specific treatment effects,

was 14.3500 sec., whereas for females the corresponding mean was 9.0300

sec. This difference was not noted by Reichenberg (1953) in a study of








the effect of stimulus form, for a constant rate, in which nean dura-

tions were obtained. In the study by Rouse (1960) with a sample of men-

tally retarded subjects of ages 15 to 25 years of ago, the upper thres-

hold of movement, in terms of flash rate, w;as significantly higher for

male subjects. This variable, rate of alternation, cannot be directly

compared with the mean duration. Rouse pointed out the difference in

perception which involved the sex of the subject may be involved in

test-sex interactions and direction-sex interactions.

Other perceptual studies by Witkin and Uapner (1950) and by

Wapner and Witkin (1950) relating factors in the visual field to the

maintenance of upright posture and body balance reported some significant

differences in the performance of their male and female subjects. In

their research,performances for both males and females were poorest

under conditions of unstable visual fields, with performance for females

being more strongly affected than for males. They reported that females

were more highly dependent on the visual field than were males and they

also reported great individual differences among both their male and

female subjects. With reference to the results of the present study, it

is possible that the females' greater "field dependence" may account for

their lower mean durations of perceived apparent motion, especially under

conditions of ambiguous or unstable visual fields. If field dependence

is involved (this research did not establish such reference), the

difference may be attributed to unknown field factors.















CHAPTER V


SUMMARY AND CONCLUSIONS



The purpose of this study was to determine the effects of

psychophysical method (method of constant stimuli and method of limits),

degree of dysphoria (ranging from zero to 28 prism diopters in eight

equal steps), horizontal (esophoria)-vertical (hyperphoria) orienta-

tion in dysphoria, and the interactions of these variables on the

perception of (beta) apparent motion.

Data from 50 subjects, 25 males and 25 females, were obtained.

The design of the study provided that all subjects receive all

treatment combinations in the same order of presentation. Of the three

major variables there were eight levels of degree of dysphoria (variable

A), two levels of variable B (horizontal-vertical orientation of

dysphoria), and two levels of variable C methodd of constant stimuli

and method of limits). An AO phorometer was used to experimentally in-

duce dysphoria in the subjects. The eight levels of variable A were

obtained by eight settings, in prism diopters, of one (left) of the

prisms of the phorometer. The prism positions also produced the hori-

zontal (esophoric) and vertical (hyperphoric) orientaticns.

The data were treated by means of two analyses of variance, one

analysis pertaining to the data for each sex, male and female. The

analyses were performed by the University Computing Center of the

University of Florida.









Three hypotheses c yere examined in this study: (1) an increase

in phoric imbalance may further a decrease in the mean duration of

perceived apparent notion; (2) for a horizontal movement direction,

horizontal dysphoria may be more disruptive to the perception of

apparent motion than a condition of vertical dysphoria; and (3) the

serial exploration (limits) nay extend the range of apparent motion.

Results of the study indicated support of the second hypothesis

for both males and females. For male subjects it was found tha psycho-

physical method was a significant factor influencing the mean duration

of perceived apparent motion, but a higher mean duration was obtained

for the method of constant stimuli than for the method of limits. The

degree of dysphoria was found to be non-significant for both males and

females.

Perceptual theory concerned with apparent movement classically

has been oriented to a central integrative process. The results of this

research have not altered the theory. It was also concluded that

apparent motion is a highly stable phenomenon, seemingly unaffected by

induced peripheral changes in an observer's normal method of perceiving

his world.







































APPENDIX














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REFERENCES


Boring, E. G. Sensation and perception in the history of experimental
psychology. New York: Appleton-Century-Crofts, 1942.

Gengerelli, J. A. Apparent movement in relation to homonymous and
heteronymous stimulation of the cerebral hemispheres. J. exp.
Psychol., 1948, 38, 592-599.

Helson, H. The psychology of gestalt. Amer. J. Psychol., 1925, 36,
494-526.

Home, E. P., and Deabler, H. L. Optimal beta notion in patients re-
ceiving insulin and chlorpromazine treatment. J. gen. Psychol.,
1962, 67, 265-269.

Kenkel, F. Untersuchungen dber den zusammenhang zwischen erscheinunga-
gr6dse und erscheinungsbewegung beim einigen sogenannten
optischen tauschungen. Zcit. f. Psychol., 1913, 61, 358-449.

Kdbhler, W. The present situation in brain physiology. Amer. Psychol.,
1958, 13, 150-154.

Lane, J. P., and Horne, E. P. Stimulus intensity and position effects
on apparent movement. J. gen. Psychol., in press.

Motokawa, K. Retinal traces and visual perception of movement. J. exp.
Psychol., 1953, 45, 360-377.

Neff, U. S. A critical investigation of the visual apprehension of
movement. Amer. J. Psychol., 1936, 48, 1-42.

Orlansky, J. The effect of similarity and difference in form on appa-
rent visual movement. Arch. Psychol., 1940, No. 246.

Reichenberg, IT. Apparent motion as a function of form. Unpublished
master's thesis, University of Florida, 1953.

Reichenberg, N. Apparent motion as a function of instruction, form and
rate. Unpublished doctoral dissertation, University of Florida,
1957.

Rouse, U. S. Thresholds of beta motion reported by mental detectives.
Unpublished master's thesis, University of Florida, 1960.









Saucer, R. T. The effect of dark adaptation upon the perception of
apparent notion. Unpublished master's thesis, University of
Florida, 1950.

Saucer, R. T. The effect of rate and energy upon the perception of
apparent motion. Unpublished doctoral dissertation, University
of Florida, 1954.

Wapner, i., and Witkin, H. A. The role of visual factors in the main-
tenance of body balance. Amer. J. Psychol., 1950, 63, 385-408.

Wertheimer, I. Experimentelle studies Uber das schen von bewegung.
Zeit. f. Psychol., 1912, 61, 161-265.

Wilson, S. R. Rate and dark adaptation as determinants of apparent
notion. Unpublished doctoral dissertation, University of
Florida, 1957.

Witkin, H. A., and Wapner, S. Visual factors in the maintenance of
upright posture. Amer. J. Psychol., 1950, 63, 31-50.















BIOGRAPHICAL SKETCH


Alan W. Pusnak was born in Chicago, Illinois, on June 3, 1937.

He attended public schools in Mliami, Florida, and received a Bachelor

of Arts degree from the University of Miami in June, 1959.

He entered the Graduate School of the University of Florida in

September, 1959, and received the Master of Arts degree in psychology

in August, 1961. He is a charter member of the University of Florida

chapter of Psi Chi.

He is presently on a post-internship grant from the National

Institutes of Vental Health, and a candidate for the Doctor of

Philosophy degree in psychology.









This dissertation was prepared under the direction of the

chairman of the candidate's supervisory committee and has been approved

by all members of that committee. It was submitted to the Dean of the

College of Arts and Sciences and to the Graduate Council, and was

approved as partial fulfillment of the requirements for the degree of

Doctor of Philosophy.



April 13, 1964










Dean, College of Arts nd Sciences






Dean, Graduate School



Supervisory/. tee:



Chairman





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