Various - Harvard Psychological Studies, Volume 1

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[1] Gallon, Francis: 'Inquiries into Human Faculty and its
Development,' London, 1883, p. 109.

More recent writers classify the students, or other persons examined,
according to these persons' own statements with regard to the nature
and degree of control over the mental images which they consider
themselves to possess. An article by Bentley[2] is the only study of a
specific problem of the memory image. After a glance at the literature
with reference to methods pursued in the investigation of problems of
memory in general, Bentley outlines 'a static and genetic account' of
the memory image in particular, and presents details of experiments
'carried on for the special investigation of the visual memory image
and its fidelity to an original presentation.'

[2] Bentley, I.M.: 'The Memory Image and its Qualitative
Fidelity,' _Am. Journ. of Psychol._, 1899, XI., pp. 1-48.

Of the many memory problems as yet unattacked, that of the control of
the mental image is one of the most interesting. The visual image
obviously offers itself as the most accessible and the experiments
described in this report were undertaken with the purpose of finding
out something about the processes by which control of this image is
secured and maintained. The report naturally has two aspects, one
numerical and the other subjective, presenting the statements of the
subjects as to their inner experiences.

The term 'suppression' is used as a convenient one to cover the
enforced disappearance of the designated image, whether it be directly
forced out of consciousness (a true suppression) or indirectly caused
to disappear through neglect, or limitation of the attention to the
other image which is to be retained.

As this was an investigation of the control of memory images, the
presence of these images under conditions most favorable to their
vividness and distinctness was desirable. An immediate mental recall
at the end of five seconds of visual stimulation, under favorable
though not unusual conditions of light, position and distance, seemed
most likely to secure this desideratum. Experimentation showed that
five minutes was, on the whole, a suitable period in which to secure
the information needed without developing a fatigue in the subject
which would vitiate the results.

The experiments made in the visual field were restricted to visual
memory images which were called up by the subject during the five
minutes succeeding a five seconds' presentation of one or two objects.
The subject sat, with his eyes closed, about four feet from a wall or
screen, before which the object was placed. At a signal the eyes were
opened, and at a second signal five seconds later they were closed. If
an after-image appeared the subject reported its disappearance, and
then called up the image of the object just presented, and reported as
to its clearness, vividness, persistency and whatever phenomena arose;
and when directed he sought to modify the image in various ways to be
described later.

There were six subjects in experiments conducted during the winter of
1900-1901, and six (five being new ones) in experiments of the fall
of 1901. They were all good visualizers, though they differed in the
readiness with which they visualized respectively form or color.

The experiments of the first few weeks were designed to establish the
fact of control by the subjects over a single visual memory image as
to its position, size, outline, color, movement and presence. In
general it was established that a considerable degree of control in
these particulars existed in these subjects.

Later, two objects were presented at a time, and were such small
articles as a glass ball, a book, a silk purse, an eye-glass case, an
iron hook, and so forth. Still later, colored squares, triangles, or
discs were used exclusively.

The investigation followed these lines: I. Movements of a single
image; II. Changes of color of a single image; III. Movements of two
images in the same and in different directions; IV. Suppression of one
of two images; V. Movements of a single image, the object having been
moved during the exposure.

I. MOVEMENTS OF A SINGLE IMAGE.

The first table gives the time in seconds taken to move voluntarily a
single image (of a colored square or disc) to the right, left, up or
down, and in each case to restore it to its original position. There
were thirty movements of each kind for each of the six subjects,
making one hundred and eighty for each direction and also for each
return, the total of all movements being fourteen hundred and forty.
The distance to which the subjects moved the images was not fixed, but
was in most cases about twelve inches. The time was taken with a
stop-watch, and includes the time between the word of command,
'right,' etc., of the director and the verbal report 'now' of the
subject. It includes, therefore, for each movement two reaction times.
The subject reported 'now' the instant the color reached, or appeared
at, the designated place, not waiting for the completion of the shape
which usually followed. Two of the subjects (H. and K.) took much
longer than the other four, their combined average time being almost
exactly four times the combined average time of the other four.

TABLE I.

MOVEMENTS OF A SINGLE IMAGE.

30 Movements of Each Kind for Each Subject Average Time in Seconds.

To To
Subjects Right Return Left Return Up Return Down Return Averages
B. 1.30 1.07 1.06 1.11 1.13
0.58 0.73 0.46 0.45 0.55

G. 1.44 1.15 0.99 0.82 1.10
0.92 0.89 0.76 0.57 0.78

H. 7.12 6.42 5.96 5.85 6.34
4.51 4.41 4.36 4.40 4.42

I. 1.28 1.34 1.62 1.47 1.43
0.67 0.62 0.86 0.72 0.72

J. 1.71 1.42 1.40 1.14 1.50
1.34 1.53 0.77 0.74 1.09

K. 4.81 4.64 3.29 3.28 4.01
2.40 2.71 1.91 1.56 2.14

Averages 2.95 2.67 2.39 2.23 2.59
1.72 1.82 1.52 1.41 1.62

NUMERICAL.

The general averages for the different movements show that movement to
the right was hardest, to the left next; while movement downward was
the easiest. A marked exception is seen in I., for whom the upward
movement was the hardest and movement to the right was the easiest. J.
found movement to the left hardest. For the return movements, the
general averages show that the return from the left is the hardest,
from the right next; while from below is the easiest. Here again I.
found the return from above the hardest and from below the next
hardest; while from the left was the easiest.

Arranging the subjects in the order of the average time, taken for all
the movements, including the returns to the original position, we have

H. 5.35 average time out and back.
K. 3.07 " " " " "
J. 1.29 " " " " "
I. 1.07 " " " " "
G. .94 " " " " "
B. .84 " " " " "

SUBJECTIVE.

All the six subjects whose time records appear in Table I. and also
four others whose time was not recorded reported eye movements, or a
tendency to eye movement. A. and K. reported that when the image was
dim there was accommodation as for long vision and when the image was
vivid there was accommodation as for near vision. B. ideated the new
position and the eye movement occurred automatically. G. reported a
contraction of the scalp muscles and a tendency to cast the eyes up
and locate the image at the back of the head inside; this was an
inveterate habit. He reported also accommodation for the different
distances of the image and an after-feeling of strain in the head. H.
reported a strong tendency in the eyes to return to the center,
_i.e._, the original position, and to carry the image back there. All
the subjects frequently reported a sense of relief in the eye muscles
when the command to return the image to the center was given--also, a
tension in the forehead in the upward movement which was accentuated
(with H.) when there was headache. J. reported, 'always eye strain,'
and noticed that the eyes usually turned as far as the new position,
but sometimes stopped short of it. K. reported first an eye movement,
then an ideation of the image in the new position. E. and H. turned
the head to right and left for movements of the image in those
directions. A., B., E. and F. believed that they could inhibit the eye
movement. Subjects were at times unconscious of eye movements. H.
articulated the names of the colors of the image and found that it
aided the movement of the image to say to himself, for example: "Don't
you see that blue square there?"

All but J. reported a loss in vividness and also, though to a less
degree, in distinctness whenever the image was moved away from the
center. J. found no difference. H. reported that details of the object
which were reproduced in the image when at the center were not
discernible in the image in other positions, also that at the left the
image was more vivid than at the right. B.'s memory image of a watch,
three minutes after it was called up, was still so clear that he read
from it the time. E., who was an experienced photographer, had no
difficulty in recalling outline, light and shade, but had difficulty
in reproducing color. I. frequently lost the form in making the
required improvements.

Under manipulation the memory image usually retained its distinctness
and vividness with no loss or with but slight loss when in its
original position, to the end of the five minutes of the experiment.
The image, also, seldom disappeared except for the momentary
disappearances in passing from one position to another, which are
referred to later. Under passive observation of the memory image
disappearances, though of short duration, were frequent and there was
a noticeable fading away of color and loss of outline.

The memory image almost without exception, when first recalled, was
located in the direction and at the distance of the object presented.

In moving from the center to right and left the image remained in the
same plane with a few exceptions; in moving up and down it moved on an
arc whose center was at the eye. This was especially true of the
downward motion, which was almost always to a greater distance than
any of the other motions.

C., D., F. and H. felt the need of a support for the image in any
except the central position. This was true especially of the position
above the center, but was entirely overcome by practice by C., F. and
H., and partially by D. In movements where time was to be recorded,
the distance was from six to eighteen inches, but the image could be
carried by all the eleven subjects to any part of the room or beyond
the room. Usually the method followed was to fix the attention on the
suggested position and then the image appeared there, sometimes
complete at the outset, but usually in part at first, then developing
instantly to completion. When the subject was requested to trace the
image _in transitu_, this could usually be accomplished, but the time
was much longer. Frequently, in such a case, the image was lost during
the last third or fifth of its journey. J. "felt conscious of a
something that went in the suggested direction but did not develop
details out of this material; had to await development of the image at
the new locality." "At times _forced_ this development out of the
vague something that seemed to go over." G. had 'no feeling of
transition in space.' K. did not perceive the image _in transitu_. I.
perceived the image _in transitu_ when the movement was away from the
center but when the image was to return to the center its passage was
too quick to be followed; 'it came out at the center.'

J. noticed that in moving from the center the image took a curved path
towards himself, and that the position _to_ which the image moved
always seemed further away than the position _from_ which it came, but
the new position seemed to be readjusted when the next movement
occurred.

The return to the center seemed easier to all the subjects except G.,
who was conscious of no difference between the movements with respect
to ease. Several described the return to the center as like the return
of a small ball snapped back by a stretched elastic cord.

With D. a suggestion of weight in the perception of the object was a
hindrance to moving its memory image. Also the image of a short piece
of brass tubing persisted in rolling off the table and along the floor
and could not be held stationary. Other objects rotated rapidly, and
much effort was needed to 'slow down' the rotation and to bring the
objects to rest and keep them at rest.

II. CHANGES OF COLOR OF A SINGLE IMAGE.

Tables II. and III. show the results of experiments in changing the
color of a single image. This was usually a square, sometimes a disc.
The time of optical perception was five seconds. After the
disappearance of after-images, if there were any, eighteen to
twenty-four changes were made in the color of the memory image,
occupying from four and a half to six minutes.

The colors were saturated blue, green, yellow and red, and each one
was changed into each of the other colors and then restored. The order
of change was varied to avoid uniformity of succession. The four
colors were shown to the subjects each day before the experiments
began, to establish a standard. The time was taken with a stop-watch,
and includes the time between the director's word of command, 'green,'
etc., and the subject's report, 'now,' or 'green,' etc. It includes,
therefore, two reaction times. The subject reported 'now' the instant
he secured the desired color, not waiting for the completion of the
shape that usually followed.

TABLE II.

CHANGES OF COLOR. SINGLE IMAGE. 72 CHANGES OF EACH COLOR.

[Label 1: Subject.]
[Label 2: To Green.]
[Label 3: Return to Blue.]
[Label 4: To Yellow.]
[Label 5: Return to Blue.]
[Label 6: To Red.]
[Label 7: Return to Blue.]
[Label 8: To Blue.]
[Label 9: Return to Green.]
[Label 10: To Yellow.]
[Label 11: Return to Green.]
[Label 12: To Red]
[Label 13: Return to Green.]

From Blue. From Green.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]

B. 1.72 0.50 1.66 0.38 1.81 0.50 1.23 0.56 1.10 0.65 1.33 0.56
G. 1.15 0.60 1.10 0.79 0.89 0.65 1.75 0.87 1.04 0.75 1.35 0.71
H. 4.67 4.25 4.87 4.06 4.81 3.83 5.27 4.50 5.81 4.89 5.37 4.94
I. 2.27 1.25 1.77 1.19 1.83 1.25 2.15 0.93 1.71 1.04 1.92 1.15
J. 1.38 0.81 1.29 0.94 1.29 0.95 1.65 1.08 1.15 0.77 1.60 0.81
K. 2.35 1.71 1.96 1.66 2.10 1.19 2.25 1.25 2.17 1.73 2.44 1.27

Av. 2.26 1.52 2.11 1.50 2.15 1.39 2.41 1.53 2.15 1.65 2.34 1.57

[Label 1: Subject.]
[Label 2: To Blue.]
[Label 3: Return to Yellow.]
[Label 4: To Green.]
[Label 5: Return to Yellow.]
[Label 6: To Red.]
[Label 7: Return to Yellow.]
[Label 8: To Blue.]
[Label 9: Return to Red.]
[Label 10: To Green.]
[Label 11: Return to Red.]
[Label 12: To Yellow.]
[Label 13: Return to Red.]

From Yellow. From Red.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]

B. 1.79 1.06 1.35 0.87 1.89 1.10 1.54 0.58 1.71 0.62 1.31 0.71
G. 1.50 1.10 1.48 0.87 1.31 0.88 1.33 0.92 1.35 0.91 0.77 0.58
H. 5.02 4.54 5.73 3.91 6.15 4.17 6.35 3.91 5.89 4.69 5.54 4.37
I. 2.29 1.31 2.54 1.19 2.29 1.27 2.85 1.10 2.50 1.21 1.65 1.31
J. 1.35 0.98 1.35 0.65 1.27 0.88 1.42 1.04 1.31 1.02 1.25 0.85
K. 3.02 1.52 3.21 2.04 2.23 1.79 2.54 1.56 2.66 1.60 2.88 1.81

Av. 2.49 1.76 2.61 1.59 2.52 1.68 2.67 1.51 2.57 1.68 2.23 1.62

TABLE III.

CHANGES TO THE FOUR COLORS.

Average time in seconds. 72 changes from and 72 changes to each color.

[Label 1: To Blue.]
[Label 2: Return from Blue.]
[Label 3: To Green.]
[Label 4: Return from Green.]
[Label 5: To Yellow.]
[Label 6: Return from Yellow.]
[Label 7: To Red.]
[Label 8: Return from Red.]

[1] [2] [3] [4] [5] [6] [7] [8]
From blue, 2.26 1.52 2.11 1.50 2.12 1.39
" green, 2.38 1.53 2.16 1.64 2.33 1.57
" yellow, 2.49 1.75 2.61 1.59 2.52 1.68
" red, 2.67 1.52 2.58 1.68 2.27 1.62

Average, 2.52 1.60 2.48 1.59 2.17 1.58 2.33 1.55

_Changes from_ a presented color. _Returns to_ a presented color.
216 movements. 216 movements.

_From_ presented yellow, 2.52 _To_ presented yellow, 1.67
" " red, 2.49 " " red, 1.61
" " green, 2.29 " " green, 1.58
" " blue, 2.16 " " blue, 1.47

Average, 2.37 Average, 1.58

_Changes to_ a color _from_ _Returns from_ a color _to_
a presented color. a presented color.
216 movements. 216 movements.

_To_ blue, 2.52 _From_ blue, 1.60
" green, 2.48 " green, 1.59
" red, 2.33 " yellow, 1.58
" yellow, 2.17 " red, 1.55

Average, 2.37 Average, 1.58

The six subjects fall into two groups--three, H., I., and K., taking
longer than the other three. As in the previous experiment H. was
markedly longer than any of the others.

There were seventeen hundred and twenty-eight changes in all,
including returns to the original color. There were two hundred and
sixteen changes from each of the four colors as presented, to each of
the other three and, of course, the same number of returns to the
presented color.

The change to blue from the other presented colors was the most
difficult and the change to yellow was the easiest.

The averages (216 exp. each) are,

Sec.
To blue, 2.55
" green, 2.48
" red, 2.33
" yellow, 2.17

The returns to the presented colors did not differ greatly from each
other, the averages (216 exp. each) being:

Sec.
From blue, 1.603
" green, 1.597
" yellow, 1.589
" red, 1.549

From red appears to be the easiest change, and from blue the hardest.

The getting away from a presented blue was the easiest and from a
presented yellow the most difficult, as seen by these averages (216
exp. each):

Sec.
From yellow, 2.54
" red, 2.49
" green, 2.29
" blue, 2.16

The returns to the presented colors show that it was hardest to get
back to the presented yellow, easiest to get back to the presented
blue, the averages (216 exp. each), being:

Sec.
To yellow, 1.67
" red, 1.61
" green, 1.58
" blue, 1.47

The facts as to blue and yellow shown by these four tables of averages
may be expressed also in this way:

If a blue square was shown, it was easier to change the blue memory
image into the other colors, and also easier to get back the blue
memory image after such changes, than if any other of the three colors
was presented.

If another color than blue was shown it was harder to change the
memory image of that color to blue than to any of the other colors,
and also harder to get back to the memory image of that color from
blue than from any of the other three colors.

If a yellow square was shown, it was harder to change the yellow
memory image into the other colors, and also harder to get back the
yellow memory image after such changes than if any other of the three
colors was presented.

If another color than yellow was shown, it was easier to change the
memory image of that color to yellow than to any of the three other
colors, and also easier to get back to the memory image of that color
from the yellow than from any of the other three colors except red.

If we combine _all_ the changes into a color (both changes from
another presented color and returns to this color previously
presented) we find that changes to green are hardest, to yellow
easiest. The averages (for 432 exp. each) are,

Sec.
To green, 2.03
" blue, 1.99
" red, 1.97
" yellow, 1.92

The changes away from a color (both from this color previously
presented and from this color to the other previously presented
colors) show that it was hardest to get away from yellow, easiest to
get away from blue, the averages (for 432 exp. each) being:

Sec.
From yellow, 2.06
" red, 2.02
" green, 1.94
" blue, 1.88

As for the subjects, all six found yellow the easiest to change into,
one finding red equally easy.

SUBJECTIVE.

For seven of the subjects, mental repetition of the name of the color
(usually accompanied by articulatory movements) tended to bring up the
color, and one other subject occasionally used this method of bringing
about a change that was difficult. With D. the color did not come at
repetition of the name. G. was assisted by auditory recall of the
name. Nine subjects reported a feeling of strain, usually in the eyes
as of focusing, occurring especially when there seemed a difficulty in
producing the desired change. The tension attended almost exclusively
changes of the presented color, not restorations of that color. For D.
this strain was considerable, for G. there was also an after-feeling
of strain in the head. For G. the image was clearest when the feeling
of strain was least, and J. secured the promptest and clearest results
when he could most nearly rid himself of anxiety as to the result. K.
in one instance (a change from green to yellow) became conscious of
the setting of his jaws and motions of feet and body in aid of his
attempt. H. frequently had the feeling of physical fatigue.

In most cases the restoration of the presented color was as a complete
square, triangle, etc. In changes from the presented color the new
color appeared at a corner, or edge, or as a patch at the center. With
E. the "color flashed over the whole field and then had to be
restricted to the figure." B. "held the outline, emptied of the old
color, while it was filled in with the new." D. "had a clear outline,
and the new color came in small blotches inside, and effort spread
them out to cover the whole figure." For I. the "new color came
sliding in from the right side over the old, which, however,
disappeared as if it were moving out of focus." With A. the new color
usually came from either the lower left-hand or the upper right-hand
corner. F. kept a clear outline and the new color came in from the
right.

When E. found it difficult to create at the center the desired color,
he thought of some object (garment, grass, sky, etc.) of that color
and then transferred it to fill in the outline preserved at the
center. B. moved the colored figure aside and in its place put one of
the desired color, moved the new figure up to the old and there
superposed it. With G. the new colors seemed of new material and there
was felt to be an accumulation about the center, of old
color-material. Then he located the square outside of this imaginary
debris and began again. H. found that the colors of his own
experiments, in which he used color squares framed in black, came to
his mind at the names of the desired colors, and the association soon
gave him the figure also. I. located the new colors around the
presented one, first all at the right; then green at the left, red at
the right, yellow above, when presented blue was at the center; then
yellow and green were at the upper left-hand corner, while red came
from behind. The new color 'slid in over the old.' It was found easier
to secure the desired color when its position was known beforehand. J.
also used a similar device. He 'turned towards the places and brought
out the required color and filled the central outline with it.' He
tried to break up this scheme and got red without going after it but
found himself 'at a loss to find the colors.' Later he succeeded so
that the required color simply appeared in the outline of the old
color at the center. K. turned his eyes to corners of the central
outline, then to the center, and found that this aided in developing
the desired color from the corners inward. When difficulty arose, he
experienced muscular tension in body and legs and jaws.

Five of the subjects considered the change from a presented color to
blue the hardest and one found the change to red hardest. Green was
placed second in difficulty by one, and blue second by the one who
found red the hardest. Three reported the change to yellow the easiest
and two the change to red.