Sixteen Experimental Investigations from the Harvard Psychological Laboratory by Hugo Münsterberg (100 books to read .txt) 📕

himself, for example, having referred to instances in which the

control was lacking, goes on to say[1]: “Others have complete mastery

over their mental images. They can call up the figure of a friend and

make it sit on a chair or stand up at will; they can make it turn

round and attitudinize in any way, as by mounting it on a bicycle or

compelling it to perform gymnastic feats on a trapeze. They are able

to build up elaborate structures bit by bit in their mind’s eye and

add, substract or alter at will and at leisure.”

[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