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OCULAR DOMINANCE IN VISUAL SCANNING

BY

Stuart J. Agres

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF ARTS
Department of Psychology

1968

‘k .A—----.or.-

ACKNOWLEDGMENTS

I should like to express my sincere appreciation
and thanks to the members of my committee:. Paul Bakan,
John McKinney, Charles Henley and Donald Johnson; for their
, individual and joint concern and advice throughout this
study.

Special thanks is extended to Dr. Bakan the Chair-
man of this committee, who, though partially through cir-
cumstances, spurred me on toward prompt completion of the
‘ thesis.

I also wish to thank Dr. McKinney for assuming
chairmanship of the committee in Dr. Bakan's absence and
for his encouragement and suggestions in the final writing
of this thesis. ‘

Appreciation is also extended to Gary Connor for
his ingenuity and special talent in devising the electrical
apparatus used, and to M. Nivison and M. Brown for their

assistance throughout this venture.

._~——_..__—__ A...” -_...-._...__.._r _

ABSTRACT
OCULAR DOMINANCE IN VISUAL' SCANNING
by Stuart J. Agres

A study to test for differences in scanning behavior
due to ocular dominance was conducted utilizing a new method
of stimulus presentation. Previous studies on scanning
typically used tachistoscopic presentations. In the pres-
ent study §s saw lights presented against a dark background.
As suggested by other studies, it was hypothesized that
‘scanning proceeds inward from the periphery. It was an-
ticipated that differences in ocular dominance would pro-
duce stronger "extreme-torcenter" scanning in either the
right or left visual fields depending upon the ocular
dominance of g.

56 college gs, equally divided by both sex and
ocular dominance, were tested under 2 conditions (28 §5
participating in each). In Condition 1 gs fixated at the
center of the display board; in Condition 2 the fixation-
point was midway between the display board and g. The
presentation of 2 bulbs to either the right or the left
halves of the display board constituted each experimental

trial. In each trial the 2 bulbs were either flashed

Stuart J. Agres

simultaneously or there was a delay in onset between the 2
bulbs, this done to assess actual discrimination ability
in each visual field.

No significant differences in scanning behavior
due to ocular dominance differences were observed in Con-
dition 1. In Condition 2 the more extreme bulb was seen
as going on first (p < .01) by both right and left-eye
dominant gs. Also in Condition 2 the left field was bet-
ter discriminated by both groups, on delayed-onset trials
(p < .01). An explanation of differential attention is

suggested for this later result.

Approved 07/2/16 é‘z'LC—Q,
/r /

Date gaff/{1744‘ /%a/fl

 

TABLE OF

ACKNOWLEDGMENTS . . . . . . .
LIST OF TABLES AND FIGURES .\.
-LIST OF APPENDICES . . . . . .
{Chapter
I. INTRODUCTION . . . . .
II. METHOD . . . .,. . . .
III. RESULTS . . . .’. . . .
_IV. DISCUSSION . . . . . .
REFERENCES .-. . . . . . . . .

APPENDICES O ‘ ' O O O O O O O O 0

CONTENTS

Page
ii

iv

14
25
30
33

LIST OF TABLES AND FIGURES

Average scores for each subgroup in
Condition 1 (all trials) . . . . . . . .

Analysis of Variance of Condition 1
on simultaneous trials only . . . . . .

Average scores on correctness of delay-
presentation responses in Condition 1 .

4. Analysis of Variance of Condition 2
on simultaneous trials only . . . . . .
5. Average scores for each subgroup in
Condition 2 (all trials) . . . . . . . .
6. Analysis of Variance of Condition 2--
all trials (without ratings) . . . . . .
7. Analysis of Variance of Condition 2--
all trials (with ratings) . . . . . . .
8. Average scores on correctness of delay-
presentation responses in Condition 2‘ .
Figure
l. The extent to which one response was said
' more than the others in Condition 1 . .
2. The extent to which "extreme" was said

more than "center" in Condition 2 . . .

Page

17

18

17

20

21

21

22

22

19

24

4.0.4.

LIST OF APPENDICES

Appendix

A.
B.

C.

The Apparatus . . . . . . . . . . . . .
Directions to Subjects . . . . . . . .

Table of Presentations . . . . . . . .

I .-._ J- -“‘-~I- - --~_—,‘r»-- ‘ ' "

Page
34
36
4O

CHAPTER I

INTRODUCTION

While possibly not the first, Leonardo da Vinci.con-

ducted what was probably the-most thorough analysis of the
differences between monocular and binocular vision (this
done prior to 1500).1 Although he realized that differences
did exist between the two ways of seeing, he always seemed
to assume that the two eyes were equal in both use and
ability. I

Some of the earliest reports of differential per-
ceptual ability, due to ocular dominance, are from Porta
(1593; cited in Miles, 1929): 2

Nature has bestowed on us eyes in pairs, one at
the right hand and one at the left, so that if we are
to see anything at the right hand we make use of the
right eye. . . . Whence we always see with one eye,
although we think that both are open and that we see
with both.

Between the_two eyes let there be placed a partition
to divide the one from the other, and let us place a book
before the right eye and read. If anyone shows another
book to the left eye it will not only not be able to
read, but it cannot even see the pages, unless in a
moment it withdraws the visual virtue from the right
eye and changes it to the left. '

 

1A comprehensive history of ocular dominance to the

1920's is found in Miles (1929), some of which is cited
here as background.

If anyone places a staff before him and brings it
directly Opposite some crack that exists in the oppo-
site wall, and notes the place, when he closes his
left eye he will not see the staff removed from the
Opposite crack, the reason being that everyone looks
with his right eye as he uses his right hand.

As late as 100 years ago, it was still believed a
rarity that some people were left-eye dominant. Donders
(1864), as cited in Miles, states: "It certainly is true,
that we usually abstract from the one eye more easily than
from the other. If anyone causes to be distracted the sight
to a remote object, it appears, on subsequent closing of the
left eye, almost always, that the right eye has been used."

Shastid (cited in Schoen & Scofield, 1935) suggests
that the dominant eye is the one which gives the brain the
details of the outside world; is the more acute in relaying
the necessary visual information; and that the non-dominant
eye comes in only now and again with some accessory informa-
tion. Javel about 1870 (cited in Schoen.& Scofield, 1935)
assumed that one eye served as the directing eye for deter-

mining the object's position while the other operated only

in a supporting capacity:

Most explanations of binocular vision are accompanied
by diagrams which show a triangulation, with tho baso of
an isoceles triangle connecting the two eyes and the
apex lying at the fixation point in the midline between
them. In reality, the triangulation of binocular vision
is nearer that ofqa right triangle with the right angle
at the dominant eye (Schoen & Scofield, 1935).

Schoen & Scofield (1935), found that the non-dominant

eye serves a somewhat different function. Without stating

A__‘_‘_‘ A_____‘._.‘ 4A .- 1...4.L 4-1 4.4. ‘A Li“ L_ A _‘_ m A ‘4‘

any implications,they found that the non-dominant eye moves
faster than the dominant eye in attending to new stimuli.
In the early_129QL§i_§§uQies of dominance began to
take on a form which has been prominent until very recently:
the study of the relationship between handedness and eye-
dominance.
Elsin (1910) reported on 65 left-handed adults.
"There were 58 of the 65 patients who had equally good
vision in both eyes; but only 20 of these brought the
'finger in front of the left eye." ("Sighting-past-the
finger" method of testing for dominance.) This failure of
more than half of the left-handed to demonstrate left-
eyedness in this task was believed especially remarkable,
for he had previously found all right-handed to be right-
eyed (cited in Miles,.1929).
In 1925, Mills published a report on eyedness and
handedness, finding:
76.0% right-eyed and right-handed
13.0%-1eft-eyed and right-handed
9.3% left-eyed and left-handed
1.7% right-eyed and left-handed
Recent studies have also found the low correlation
between handedness and eyedness (Cole, 1957; Fuller & Thomp-
son, 1960; Kruper, Boyle & Patton, 1966;_Merrell, 1957),
leading Kruper, Boyle & Patton (1966) to say: "It would
seem that eye and hand preference are not mediated by a

simple common factor, e.g. a single dominant hemisphere."

 

Recent perceptual studies which may pertain to eye-
dominance, are in actuality, typically, concerned with
scanning behavior, utilizing dominance (hemispheric), where
helpful, as an explanation. These studies utilized tachis-
toscopic presentations Of words, letters, geometric forms,
etc., presenting these stimuli either to the left or to
the right Of fixation, or to both simultaneously.

The general trend of findings in these tachisto-
scopic scanning experiments has been that when a single
letter is exposed to either the left or right fields suc-
cessively, it is more easily identified when it appears
in the right (Bryden, 1966; Bryden & Rainey, 1963; Heron,
1957). Geometric forms or nonsense figures tend not
tO show such differences (Bryden & Rainey, 1963; Heron,
1957; Terrace, 1959).

The findings of right field superiority on suc-
cessively presented stimulus items previously cited, are
explained by Heron (1957) as being due to a learned scan-
ning process (due to the left-to-right reading Of the
English language). Presentation of stimuli to the right
are more readily identified than those which are at another
time presented to the left when the eyes are fixed at the
center point of a visual field because the eyes are
already located left of the stimulus, allowing the "normal"

left-to-right scanning to Operate.

In addition to the left or right field placement,
the orientation of the material has alternative significance.
Mishkin & Forgays (1953) found that Jewish words were more
easily identified by Jewish reading Se in the left field.
Harcum & Finkel (1963), found that mirror-imaged words of
English were also better identified in the left; but when
normally oriented, these words were better discriminated
to the right of fixation.

There have been conflicting reports in further
studies. Jewish readers sighting Jewish material are only
superior in the left field if Jewish was the first language
learned. Further, mirror images of single letters are more
easily seen in the right field (when right-handed subjects
are used; Bryden, 1966), suggesting to Bryden that: "Hemi-
spheric dominance is more important than directional scan-
ning in determining left-right differences in the recogni-
tion Of single letter material" (Bryden, 1966).

Bryden's study fails, however, to completely test
out this argument, in that no left-handed group was used;
nor has it been conclusively shown that handedness predicts
hemispheric dominance. Handedness has certainly not been a
predictor Of eyedness. ~

The previously cited studies of the left-right
perceptual differences all deal with the presentation of
materials to either the left 93 the right fields succes-

sively. When stimuli are presented to both fields

simultaneously, it has generally been found that the left
field is better perceived than the right (Crosland, 1931;
Crosland, 1939; Heron, 1957), with this difference being
found greater for right-eyed subjects than for left-eyed
(Crosland, 1939). Dallenbach (1923) found that stimuli
presented to the non-dominant hemisphere were more intense
for the right handed.

Harcum and Dyer (1962) proposed that:

If the visual Objects are too numerous or too complex
to be perceived in their entirety, the component'ele-
ments must be attended to in some sequence, starting
at some reference point. This may require a scanning
of the visual field even when the eyes are fixed.

. . . The selection of the beginning reference point
in the right or left visual field for the scan may be
determined by the perceived clarity of the stimuli.
Dallenbach suggested that the distribution of atten-
tion may produce such greater clarity for the stimulus
in the left visual field for most 9s.

A combined study Of both of these methods Of pres-
entation to the two visual fields (successive and simul-
taneous), was conducted by Bryden and Rainey (1963). "In
the simultaneous presentation condition, all types of mate-
rial (letters, geometric forms, and outline drawings) were
more readily recognized in the left visual field. . . .
With successive presentation, a right field superiority
. . . was Observed."

Early studies of ocular dominance attributed little
significance to the role of the non-dominant eye in percep-
tion. The non-dominant eye has been asserted to be no more

than auxiliary to the dominant--though probably a necessary

one, in giving information regarding depth and dimension.

In addition, it was thought that the dominant eye was the
first to "see" a stimulus and was better able tO maintain
fixation on it. In 1935, Schoen & Scofield found that the
ngnfdominant eye moves more quickly in adjusting to new
stimuli, though this finding was not put to use in a pos-
sible refutiation of other of the many beliefs about the
nature of eye-dominance.

The present study was undertaken to assess ocular
dominance differences in a simple visual discrimination
task. Because the non-dominant eye does move more quickly,
it was hoped that differences would occur between right and
left eye-dominant individuals when a scanning task (with
presentations to either side and across fixation) was used.

A previous experimental task was sought, which would
fulfill the requisite demands of this experiment and allow
for anticipation of the direction of the results. A study
by' Mackworth (1965) showed that it appeared that scanning
proceeded from the periphery to the center (no right or
left field differences noted). The experiment called for
an identification of a peripheral stimulus when extraneous
stimuli were present, either more external or internal to
the required target stimulus. Mackworth found that the
more external stimuli significantly increased time necessary
for the task, while internally presented extraneous stimuli
had much less effect, thereby concluding that scanning may

proceed from the periphery to the center.

 

 

 

Since this seemed a possible area for testing dis-

criminational differences due to ocular dominance, it was

decided that an experiment to test for this scanning phe-
nomenon, with analysis for ocular dominance differences,
would prove worthwhile. If scanning did progress as hy-
pothesized, it was reasoned that a simple discrimination
task which involved scanning as an integral part, and did
not necessitate memory (even relatively short term memory)

would best accomplish the demands presented.

CHAPTER I I
METHOD

A scanning task was develOped, wherein the subject
was to make judgments as to which of two adjacent lights
went on first, when these lights were presented peripherally
in either the right or the left visual field (oral responses).
If scanning progressed as hypothesized, from the periphery
to the center, it was expected that the lights most external
to the fixation point should be seen as going on first more
Often than those internally adjacent, when the onset of the

two were simultaneous.

Subjects

 

gs were 56 college students enrolled in an elementary
course in psychology, partially fulfilling course require-
ments. Twenty-eight female (14 right-eyed and 14 left-eyed)
and 28 male (l4-right-eyed and 14 left-eyed) were divided.
into two experimental groups. Each experimental group con:
tained 28 SS; seven right-eyed males, seven right-eyed fe-
males,_seven left-eyed males and seven left-eyed females.

To assess dominance, each S was tested for ocular
dominance by the use of three common tests for dominance:

(a) sighting through a tube, (b) a'cone and (c) through a

Y
EPARTN‘E'" oF PENN gas)”
9 o N STATE U
lAICHEG'A _ ..|(‘HIGAN

 

10

1/2 in. hole in a piece of cardboard. For acceptance each

g had to pass all three tests consistently, twice.

Apparatus

 

Four neon bulbs (GE #NEBO) were mounted 1/2 in.
behind a 44 by 28 in. neutral gray posterboard sheet. Four
holes, 3/8 in. in diameter, through the board at distances
of 9-1/2 and 13 in. from either side of the center Of the
board, and 12 in. from the bottom corresponded exactly to
the placement of the bulbs.

Running horizontally from the left extreme hole to
the right extreme hole was a painted strip (off-white) ap-
proximately 1/8 in. in width. At the center of the board
was a short (3/4 in.) vertical line, also 1/8 in. in width.

This display board was curved so that it was approx-
imately 70 in. from the subject at all critical points, thus
making the visual angles 7°45' and 10°30' to the "central"
and "extreme" bulbs respectively. D.C. current (negative
pole to the center Of_the_bulblmgf 110 V. was used for illu-~
minating the bulbs, so that only the center target (1/2 in.
in diamter) of the bulbs was lit.

The apparatus was designed so that only either the
right field bulbs or the left field bulbs could be turned
on. It was also designed so that either the center or ex-
treme bulbs could have a delayed onset (42 msec.) or so

that they were simultaneous. This could be accomplished

 

11

either from the experimenter's control.box (for the prac-
tice trials) or automatically, as to prior programming (for
the experimental trials).

Though the bulbs could be delayed in onset, they
always terminated simultaneously. Total time on for the
initially onsetted bulb (and for both bulbs when simul-
taneous) was 0.372 sec. This time being found Optimal
during pilot studies.

Room illumination was kept at a constant low level
by bouncing a high intensity light from behind g, off
the white ceiling, in the otherwise dark room, thereby

illuminating equally all parts of the display board.

 

_._.-_. “M-
—._.-__..‘_

NO potentially distracting stimuli were noted to
be present in the §fs field Of vision, nor were any ever
reported by an S.

A chrome plated music stand base and pole were
used during Condition 2. (See Appendix A for pictures of

\the display board.)

Procedure

g sat at a table with a variable height chin rest,
70 inches from the display board. During all instruc-
tion periods, gs were instructed to keep their eyes closed;
this was done to both rest and adapt their eyes to the dim
illumination condition Of the room. Each trial consisted
Of the presentation Of two adjacent bulbs; either the two

bulbs to the right or those to the left of fixation.

12

CONDITION 1

gs sat as described above, and were instructed to
fixate at the center point of the display board. gs re-
ceived further instruction to signify which of the two
bulbs they Observed as going on first, signifying the one
closer to the center of the board as "center," and the ad-
jacent bulb as "extreme." Each S was asked to say "ready"
when he was sure he was once again looking at the center
point of the board.

Practice consisted of up to 62 trials with lights
flashed according to a random, but balanced, schedule. g
met criterion when he was able to discriminate correctly
any of the seven from 10 consecutive trials (after the
first 14). gs who could not reach this criterion were
terminated at the 62nd trial.
_ Rest periods of 15 seconds were administered after*
every 14 and 10 trials (i.e., after trials #14, #24, #48,
#62) during practice. When S completed practice, he was
instructed to close and rest his eyes during which time
the remainder of the instructions were.read; the experiment
was then begun.

Presentations consisted of 44 randomly selected
trials, Of which 20 were of the same delay as during prac-
tice; 10 of these to the right and 10 to the left (5 rt.-

center, 5-rt.-extreme, 5 leftecenter, 5 lefteextreme).

13

Twenty-four-simultaneous (no delay) trials constituted the
remainder; 12 presented to each side. (See Appendix C for
order of presentations.) After trial 30 §_received instruc-
tion to close and rest his eyes (approximately 30 sec.).

The experimental trials differed in the responses
required of S'in that he was additionally required to give
a rating Of the certainty of his Observation: ("zero,"
"one," or "two"; with-"zero" signifying a complete guess,

and "two" relative certainty.

CONDITION 2

All conditionstere similar to those for Condition
1, except that a chrome pole (adjustable for height and
left-right placement), was placed midway between the display
board and g, The tip Of-this pole-was covered for the top
1-1/2 in. with manila colored, non-reflective tape on which
a horizontal black line was drawn (1/2 in. from the tOp).
S aligned this line with the height Of the horizontal line
of the board, and then centered this pole with the center
of the board (sighting with dominant-eye only). The line ‘
on the pole then coincided with S's view of the fixation

point of the board.

Ss received instructiontx>always fixate at the line
on the pole, and after each trial, to tell when they were
ready for the next trial; when they were looking at the

.pole tip. Practice and experimental trials both utilized

the pole as the fixation. (See Appendix B, for complete

instructions to the subject.)

CHAPTER III
RESULTS

Five scores were obtained for each §Ito assess any

/

differences between the groups:

l."A score was Obtained for each S’by counting the num-
ber of extreme (+1) responses and center (-1) responses, on
trials where the two lights on either side were'presented

with no-delay in onset.

2. A score Obtained by including all trials (delayed

and simultaneous in onset)-

3. A score Obtained by considering the rating given
for each trial, multiplying that rating ("0," "l," or "2")

by the response (center (-1), or extreme (+1)). 0n delayed

~\

14

15

onset trials, a score Of zero was given for a correct re-
sponse; a score Of "2" (times the rating) if the response
"extreme" was given to a center-first presentation; a re-
sponse of "center" was scored as "-2" (times the rating)
if the presentation was extreme-first.

Thus a score of "0" would be Obtained if the S ran-
domly guessed on the simultaneous and either (1) guessed on
the delayed, or (2) was correct on the delayed onset trials.

A The higher sOores for misnaming on delayed trials
was done as it was considered a more significant error (in
calling, for example, a presentation, "center," if it were
actually extreme, than if the lights were presented simul-
taneously).

4. An "efficiency" score was obtained, by considering
only delayed onset trials. Scores of "2" or "-2" were
given for correct or incorrect responses respectively, on
delay trials. The scores then multiplied by the rating
given to each response.

5. A score Obtained as in 3 above, but only on delayed
onset trials and regardless Ofthe correctness or incorrect-
ness Of the response. Scores then Obtained would point to

the direction Of errors on delay trials.

In the scores Obtained by methods 3, 4, and 5, rat-
ings were utilized to both obtain st degree Of certainty

regarding his response (which was considered to be Of

16

potential importance) and to relieve any possible frustra-
tion due to the large number of simultaneous-onset trials;

S could not give "same" as a response.

Condition 1

Two hypotheses were tested for originally, in each
Of the two experimental conditions: (1) that extreme lights,
would be seen more Often than center (when simultaneous)
,and (2) that there would be differences due to ocular domi-
nance. ’“““‘““““-~~-

A summary Of resulting averages for each subgroup
in Condition 1, is found in Table 1 (average score over all
trials, with ratings). Analysis of variance does not show
significance for this measure. There is no trend of extreme
seen before center and right-left field differences are not
significant. There does however appear to be a trend of a
right hand bulb being seen before its adjacent left hand
bulb (a general trend Of right-to-left movement) in both
fields.

Analysis of scores on simultaneous trials only,
without ratings, is given in Table 2. Once again, analysis
of variance does not show significance. Analysis on simul-
taneous trials only, with ratings, show this same lack of
significance.

As relatively high sample variances were Obtained,

it was felt that the degree to which §_was actually able

17

TABLE 1

AVERAGE SCORES FOR EACH SUBGROUP IN CONDITION 1, AVERAGED
OVER ALL TRIALS.

 

 

 

 

 

m: I
Left field Right field
Left
Males
Rt.
eyed -l.86 3.71
Left
eyed -2.29 3.57
Females
Rt.
eyed -6.00 3.43
TABLE 3

AVERAGE SCORES ON CORRECTNESS OF DELAY-PRESENTATION
RESPONSES, CONDITION 1.

 

 

 

 

 

M
Left field Right field
Left
eyed ' 25.14 23.14
Males ’
Rt.
eyed 22.86 ' 26.86
Left
eyed 16.57 9.14
Females
Rt.

eyed 25.71 21.43

 

18

to discriminate differences when such differences did exist,
would be an influencing factor on scores. The scoring out-
lined in 4 was utilized in this analysis; no significant
field or sex or dominance differences were Obtained (see

Table 3).

TABLE 2

ANALYSIS OF VARIANCE, CONDITION l,SIMULTANEOUS TRIALS ONLY
--No RATINGS. ~ . -

 

 

ss df MS f
Eyedness 18.285 1 18.285
Field ' 35.571 1 35.571 _ 1.458
Eyedness X Field 0.000 1 0.000
Error 1268.002 - 52 24.4
Totals ' 1320.858 55

 

One further analysis was conducted to see where the
errors were, when discriminations were incorrect on the
delay-onset trials. Scores for this measure were obtained
by multiplying the rating by the response (see Fig. 1).

The report of "extreme" more than "center" on these trials
.(all st, both fields) is significant (p < .01, sign-test;

p < .05, Wilcoxon sign-rank test).

19

 

7" ------ Rt. field

6- \ —— Left field

 

 

J 1 l

i I I I
Female Male Female Male
L-eyed L-eyed R-eyed R-eyed

 

Fig. l.--The extent to which one response was
said more than the other in Condition 1. '(A
positive score indicates extreme more'than=
center; a negative score, center more than-ex-
treme.) :'.:-' ',‘. '

20

Condition 2

As in Condition 1, analysis Of simultaneous trials
and overall averages, averages on discrimination ability,
and errors in discrimination were conducted and are sum-

marized in Tables 5, 6, 7 and 8 and in Fig. 2.

TABLE 4

ANALYSIS OF VARIANCE, CONDITION 2, SIMULTANEOUS TRIALS ONLY
' --NO RATINGS.

 

 

 

SS df‘ MS f
Eyedness 39.446 1 39.446 1.282
Field 189.446 1 189.446' 6.159*
Eyedness X Field 75.445 1 75.445 2.453
Error 1599.503 52 30.76
Totals 1903.840 55

 

*p < .025.

Analysis Of all trials with or without ratings did
not reach significance (see Tables 5, 6 and 7). Analysis
Of simultaneous trials without ratings showed a significant
(p < .025) right-left field difference, the right field
being more extreme-to-center and the left field center-to-

extreme.(see Table 4).

In analysis for discrimination ability (Table 8)

the left field is better discriminated than the'right field,

21

TABLE

5

AVERAGE SCORES FOR EACH SUBGROUP IN CONDITION 2, AVERAGED

OVER ALL TRIALS.

 

 

 

 

 

Left field Right field

Left

eyed -2.28 2.28
Males

Rt.

eyed 1.71 2.85

Left

eyed -e aAlilmiiii,h 4.28
Females

Rt.

eyed -2.00 -3.00

TABLE 6

ANALYSIS OF VARIANCE, ALL TRIALS OF CONDITION 2
(SIMULTANEOUS AND NON-SIMULTANEOUS)--NO RATINGS

 

 

 

SS df MS f
Eyedness. 70.875 1 70.875 1.087
Field 236.160 1 236.160 .3.456
Eyedness X Field 182.160 1 182.160 2.665
Error 3553.788 52 68.342
Totals 4042.983 55

 

22

TABLE 7

ANALYSIS OF VARIANCE, ALL TRIALS OF CONDITION 2--NO RATINGS

 

 

 

SS df MS
Eyedness 0.017 1 0.017
Field 161.160 1 161.160 2.131
Eyedness X Field 154.446 1 154.446 2.043
Errors 3950.931 52 75.594
Totals 4266.554 55
TABLE 8

AVERAGE SCORES ON CORRECTNESS OF DELAY-PRESENTATION

RESPONSES, CONDITION 2

 

 

Left field Right field

Left

eyed 21.71 12.86
Males

Rt.

eyed 19.43 13.71

Left

eyed 25.43 18.29
Females

Rt.

eyed 23.71 18.86

 

23

when a real difference in onset is presented (p < .01,
Wilcoxon sign-rank; p < .01 sign-test), this difference-
being somewhat, though not significantly, greater for left
eyed gs. .

Analysis for differences between fields, dominance
and sex showed no significant results when errors in dis-
crimination are Observed (Fig. 2). Within groups, signifi-
cant reporting Of extreme more than center is noted; both
male and female left-eyed (p = .05, Wilcoxon sign-rank;

p <..025 sign-test), and male and female right-eyed §S

(p - .02, Wilcoxon sign-rank; p < .01, sign-test).

24

 

 

 

 

 

6 - -'----- Left field
5- — Right field
/
/
I
I I’ I I
Female Male, Female Male

L-eyed L-eyed R—eyed R-eyed

Fig. 2.--The extent to which "extreme" was
said more than "center" in Condition 2.
(These resulting averages include ratings
Offered for each response.)

CHAPTER IV
DISCUSSION

In an attempt partially to replicate previous stud-
ies, the fixation point in Condition 1 was at the same dis-
tance as the stimuli. Condition 2, which utilized a nearer
fixation point, was believed to be more closely related to
the everyday visual experiences of people. Very Often we
look at something close at hand and still are aware of
Objects and especially movement farther away.

It was also believed that presentation . Of a
fixation nearer §_would amplify any differences due to both
the greater expected attention to the fixatiOn and also be-
cause of the slightly greater angle at which the non-
dominant eye would be forced to look.

It should be noted here that Condition 1 experiment
was conducted prior to that Of Condition 2.

It appears that most earlier studies of scanning
argue for a learned process, that begins at the left and
proceeds to the right (in English reading gs). The results
obtained from these previous studies (e.g., Heron, 1957)
are almost invariably that the left field is better dis-
criminated than the~right, in experiments where both fields

I

25

26

are presented simultaneously. When, howeverr-the stimulus

is presented to either the right or the left successively,
the right field is better. These results being found fOr
letters and words. When, however, geometric forms, pictures,
etc., are used as the stimuli, the results become less ex-
treme or entirely absent;

The current experiment did not show this to be true:
the left field was better discriminated than the right—~the-
stimuli were presented successively to either the left or
the-right fields..

There are two possible explanations for these results.
First, it is possible that the horizontal line, which was
readily observable during as well as prior to each trial,
was more effective in duplicating a full-field presentation
than was previously believed. This line was introduced to
more closely approximate the study by Harcum and Dyer (1962),
and still not necessitate the memory problem inherent in
multiple stimuli experiments, for which they have been criti-
cized. Thus, this experiment may have succeeded in causing.
.the phenomenon observed in simultaneous presentation studies
(left field superiority).

A second possible explanation, and one which is be-
lieved to be more in-keeping with several other studies
(Dallenbach, 1923 and McKinney, 1967) concerns, in part, the
differences between the present experiment and most scanning

studies. While this experiment.did involve scanning, it was

27

not a replication of any other studies. Other stud-

ies utilized tachistoscopic presentations: a dark stimulus-
against a light background and calling fOr S to recognize
the stimulus from many possible ones, and often to remember
this observation long enough to record it. The current
experimental situation involved light stimuli against a
dark background and the response task was an immediate
verbalization of which light was seen first. This being a
much different task.

This experiment, in having a light stimulus against
a dark background, is similar in many ways to those con-
ducted by Dallenbach and McKinney. Dallenbach projected
patches of light into the two fields and McKinney had lumi-
nescent lines in the visual fields. Dallenbach's findings,
of the left field being more intense, which he believed due
to an attentional factor, appears an equally good explana-
tion of McKinney's-greater degree of fragmentation of the
left visual field. McKinney interpreted this greater frag-
mentation of the left to be due to a superiority of the
right field, which was better able to keep the line in that
field from fragmenting as often. It is, however, possible
that the greater fragmentation of the left was due to a
greater attention to that field (which should cause faster
and more frequent fragmentation), this may have predisposed
g to identify more readily what happened there. SO rather
than the right field being superior, the left may be, and

because of this superiOrityhave the observed effects.

28

This explanation makes no reference to hemispheric
‘ dominance theories to which both investigators have sub-
scribed, rather it allows for a dominance theory to explain
the greater intensity of the left field. A

It is therefore possible that the greater discrimi-
nation ability shown in this experiment for the left field,
may be of the same class as are the observations described
above. I

The extreme-before-center reports of Condition 2
are as hypothesized, though not on the trials predicted.
A possible (P2§E_Hgg) explanation for this "extreme" re-
sponse observed on non-simultaneous trials and not on simul-
taneous, may be that the response itself may not have caused
this apparent contradiction, but ratherlthe rating given to
that response.

It was possible to tell that one light came on bee
fore another, and yet not be able to identify which came on
first. It is therefore possible that extreme was always

seen before center (this was clearly not the case) but that,

 

*MMM

because the additional cue which signified a relatively long
delay between bulbs was absent, lower ratings were given to
these responses. It is also possible that a balancing was
tried, to compensate for the seeing of "extreme" when a dif-
'ference in onset times was most evident.

As a partial test for this, it was found that the

average rating given an incorrect response on delay trials

29

was significantly higher than those given for simultaneous
presentations (p < .001, sign test on Condition 2).

It should be noted that the field that was dis-
criminated best also showed the phenomenon of extreme-
before-center. It may be argued therefore that this phe-
nomenon is not caused by an inability to discriminate cor-
rectly.

One finding, which did not reach significance, is
of some interest here: the greater tendency for the con-
tralateral field to the dominant eye, to evidence a greater
extreme-before-centerness (see Fig. 2). This finding cor-
relates closely with the findings of Crovitz, Daston, &
Zener (1959) who found better recognitiOn of the target in
the opposite field of the dominant hand (most significant
when same eyedness and handedness).

Because all different methods of presentations in
visual scanning (different types of material and modes of
presentation) appear to have different results, direct com--
parisons between studies: this and previous, for example;
cannot be made with any degree of certainty. The results
of this study, then, should not be construed as being con-
trary~to results found in other experiments. The amount,
of difference in the methodologies may more than explain

the different results obtained.

REFERENCES

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apprehension scores, with'reference to reading dis-
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Ayres, J. J. & Harcum, E. R. Directional response-bias in
reproducing brief visual patterns.' Percept. mot.
Skills, 1962, 14, 155-165.

 

Barton, M. I.: Goodglass, H. & Shai, A. The differential
recognition of tachistoscopically presented English
and Hebrew word in right and left visual fields.
Percept. mot. Skills, 1965, 21, 431-437.

 

‘Bartz, A. E. Eye and head movements in peripheral vision:
Nature of compensatory eye movements. Science,
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Brown, R. & Strongman, K. T. Visual search and stimulus
‘ orientation. Percept. mot. Skills, 1966, 23(2),
539—542.

 

Bryden, M. P. Left-right differences in tachistoscopic
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1134.

 

Cole, J. Laterality in the use of the hand, foot, and eye
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Crosland, H. R. Letter-position effects, in the range of
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ters in each exposure. J. exp. Psychol., 1931, 14,
477-507.

 

. Superior elementary-school readers contrasted
with inferior readers in letter-position "range of
attention scores." J. educ. Res., 1939, 32, 410-
427.

 

Crovitz; Daston & Zener. Laterality and the phenomenon of
localization. Percept. mot. Skills, 1959, 9, 282.

30

31

Dallenbach, K. M. Position vs. intensity as a determinant

of clearness. Amer. J. Psychol., 1923, 34, 282-286.1

 

IEdwards, A. L. Experimental Design in Psychological Research.

Holt, Rinehart and WInston, N.Y., 1962.

JFuller, J. L. & Thompson, W. R. Behavior Genetics. Wiley,.
New York, 1960.

 

Gould, J. D. & Schaffer, A. Eye movement patterns during
visual information processing. Psychon. Sci., 1965,

 

Guilford, J. P. Fundamental Statistics in Psychology and
Education. McGraw-Hill, N.Y., 1965.

 

Haber, R. N. Nature of the effect of set on perception.
Psychol. Rev., 1966, 73, 335.

Harcum, E. R. Visual hemified differences as conflicts in
direction of reading. J. exp. Psychol., 1966, 72(3),
479-480.

 

. A note on "Some artifactual causes of perceptual
primacy." Psychon. Sci., 1967, 8(2), 67-68.

Harcum, E. R. & Dyer, D. Monocular and binocular reproduc—
~ tion of binary stimuli appearing right and left of
fixation. Amer. J. Psychol., 1962, 75, 56-65.

Harcum, E. R. & Finkel, M. E. Explanation of Mishkin and
Forgay's results as a directional reading conflict.
Canad. J. Psychol., 1963, 17, 224-234.

Harcum, E. R. & Smith. Effect of preknown stimulus reversals
on apparent cerebral dominance in word recognition.
Percept. mot. Skills, 1963, 17, 799-810.

Hays, W. L. Statistics for Psychologists. Holt, Rinehart,
and Winston, N.Y., 1963.

Heron, W. Perception as a function of retinal locus and at—
tention. Amer. J. Psychol., 1957, 70, 38-48.

Herrnstein & Boring. A Source Book in the History of Psy-
cholo . Harvard University Press, Cambridge, Mass.,
I965.

 

—Howard, I. P. & Templeton, W. B. Human Spatial Orientation.
John Wiley & Sons, New York, 1966.

 

32

ICruper,‘D. C.; Boyle, B. E. & Patton, R. A. Eye and hand
preference in rhesus monkeys. Psychon. Sci., 1966,
5(7), 277-278.

Efiackworth, N. H. Visual noise causes tunnel vision. Psy-
ChOD. SCio, 1965' 3' 67-680

 

IMcFarland, J. H. The effect of different sequence of part
presentation on perception of a forms parts as
simultaneous. "Proceedings of the 73rd Annual Con-
vention of the American Psychological Association,"
1965, 43-44.

. Sequential part presentation: a method of study-
ing visual form perception. Brit. J. Psychol., 1965,
56, 439-446.

 

:McKinney, J. P. Handedness, eyedness and perceptual sta—
bility of the left and right visual fields. Neuro-

Merrell, D. J. Dominance of eye and hand. Human biology,
1957, 29, 314-328.

 

uMiles, W. R. Ocular dominance demonstrated by unconscious
sighting. J. exp. Psychol., 1929, 12, ll3~126.

‘Mills, L. Amer. J. Ophth., 1925, 8, 933-941.
Mishkin, M. & Forgays, D. G. Word recognition as a func-

tion of retinal locus. J. exp. Psychol., 1953, 43,

 

Overton, W. & Wiener, M. Visual field position and word-
recognition threshold. J. exp. Psychol., 1966, 71,
249-253.

 

Schoen, Z. J. & Scofield, C. F. A study of the relative
neuromuscular efficiency of the dominant and non-

dominant eye in binocular vision. J. gen. Psychol.,
1935, 12, 156-181.

 

Taylor, S. Eye movements in reading: facts and fallacies.
Amer. Educ. Res. J., 1965, 2(4), 187-202.

-Terrace, H. S. The effect of retinal locus and attention
on the perception of words. J. exp. Psychol., 1959,
58(5), 382-385.

Toch, H. H. Can eye dominance be trainedP Percept. mot.
Skills, 1960, 11, 31-34.

APPENDICES

 

 

 

 

APPENDIX A

 

 

3a
W
0 313

D1

 

 

Overhead View of Experimental Room

lSubject

2Experimenter

3aFixation (COndition l)

3bFixation (Condition-2)

4Internal lights (7° 45').

5

External lights (10° 30')

34

 

35

 

 

  

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I“,

APPENDIX B
DIRECTIONS TO SUBJECTS

This experiment is designed to test a hypothesis
about the way peOple see; it is not in any way a test of
your personality or intelligence; but merely an attempt to
collect some data from college students, like yourself,
about the way they see.

While I am reading these instructions to you, would
you please close and rest your eyes.

' In this experiment there are two sets of lights
mounted on the board in front of you--one set to the left,
and the other to the right. Each of these sets contain two
bulbs; one, which we will call the "center," is located
somewhat closer to the center of the board than the other,
and the other we'll call the "extreme."

I (CONDITION 1 ONLY) When you open your eyes you.
will see that there is a line running across the board, and
in the center of this line, which is also the center of the
board, is a very short vertical line.’ I want you to always
'look at this point--where the vertical and horisontal.line3'.
cross. I

(CONDITION 2 ONLY) When you open your eyes and
throughout this experiment, I want you to look at the pole
Iin.front of you which-we lined up with the center point of-
the board. Remeber, you are to always look at the line on.

this pole.
36

‘37

In this experiment one of the following things will
happen: either the set of lights to the right, 2E those to
the left will go on, and each time one of these sets goes
on, you will see either the "extreme" or the "center” bulb
I go on first. Remember the extreme bulb is the one farthest
from the center of the board. I want you to tell me which
bulb went on first: the "center" or the "extreme." You
need not tell me which side went on.

Once again this_is what I'd like you to do. When
the lights Flash, tell me which of the bulbs you saw go on
first. They do go on quickly, but each time, I want you to
make the best decision that you can and give me your choice,
either "center" or "extreme.flg%$inceit is sometimes diffi-
. cult-to tell at first, I'll give you some practice trials.

-(CONDITION 1 ONLY) Remember-you are always to-look'

at the center point of the board--and after each time, would .

you please tell me when you are.sure you are once again look-

ing at the center point.

(CONDITION 2 ONLY) Remember you are to always look

at the line on the pole--and after each time, would you please

tell me when you are sure you are once again looking directly

at the line on the pole.’
In summary then, let me repeat what will happen.
Each time, either the set of bulbs to the left or those to

the right will flash on, one bulb before the other. Imme-

diately after they flash, you tell me which you saw go on_

' ""_~.".V'l'

 

4. -— —-—.—.——_—.-W _. '
u—r "... ~my~vg-‘~‘l.-<-n. F"-»~—-—\o—.‘~" '

38

:flirstq making the best decision that you can.‘ Your response'
should always be either "center" or "extreme."

(CONDITION 1 ONLY) Then when you are sure you are
Looking directly at the point where the two lines cross,
say “ready," and then we will be ready for the next trial.

(CONDITION 2 ONLY) Then when you are sure you are
looking directly-at the line on the pole, say "ready," and
then we will be ready for the next trial.

After, and during, the practice session, I"ll ask

you to close your eyes again and rest them for a while.

Do you have any questions? (Instructed to Open eyes)

 

Practice session

 

(Instructed_to close eyes)

We-are now ready for the experiment itself; and I
would like you to do exactly as you have been doing: tell-
ing me which bulb went on first. Now, however, during-some‘
cfi'the trials, the two bulbs will go on quicker than before,
'umztime between them will be shorter. I still want you to
nuke the best decision that you can, but, this time in addi-
tion to telling me either "center" or "extreme," I want you
to give me an indication of how sure you are of your-choice.‘

If you-are-fairly certain, say-"2";

39

If you think you saw it that way, say "1";

If it is a pure guess, and you might just have well

said the other, say "zero." ‘ '4
If you are fairly certain, as you probably were at

times during practice, say "2":

If you think you saw it that way, say "l";

If it's a pure guess, say "zero.”

Once again, give the best decision that you can, not
worrying about winding up with more of one response than the
other. Tell me which.you see 90 on first, and an indication

of how-sure you.are of what you saw.

Do you have any questions? (Instructed to open eyes)

 

- --fiv—V\-¢—vm

APPENDIX C

TABLE OF PRESENTATIONS

 

 

 

 

Visual Field" Delay
. . Center No Extreme
Trial NO. Right Left firSt delay firSt'
l X X
2 X X
3, X X
4 X X
5 X X
6 X' ” ‘ '-~ X
7 X X
8 X X-
9 X X
10 X X
11 X X
12 X X
13 X X
14 X ‘ X
15 X X
16 X X
17 X X
18 X X
19 X X
20 X X
21 X X
22 X X
23 X X
24 X X
25 X X
26 X x
27 X X
28 X X
29 X X
30 X X
30 sec. rest period
3? x x ‘
32 X X
33 ‘ X X
34 X X
35 X X
36 ' X X
37 ' X X
38 X X
39 X X
‘40 X, X
41 X X
42 X X
43 . X X
44 X X

40