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

locality produces upon the interval in which it occurs. These two

factors may work in conjunction or in opposition, according to

conditions. The bare constant error does not remain exactly the same

at all times for any individual and is probably less regular in

tactual time than in auditory or in optical time, according to the

irregularity actually found and for reasons which will be assigned

later.

3. The third group of experiments introduced the factor of variation

in intensity of stimulation. By the introduction of a loop in the

circuit, containing a rheostat, two strengths of current and

consequently of stimulus intensity were obtained, either of which

could be employed as desired. One intensity, designated as W, was

just strong enough to be perceived distinctly. The other intensity,

designated as S, was somewhat stronger than the intensity used in

the preceding work.

In the first instance, sixty series were taken from Subject B, with

the conditions the same as in the experiments of Group 1, except that

two types of series were taken; the first two stimulations being

strong and the third one weak in the first type (SSW), and the order

being reversed in the second type (WSS). The results gave values of

ET of 5.27 secs. for SSW and 5.9 secs. for WSS.

In order to get comprehensive qualitative results as rapidly as

possible, a three-second standard was adopted in the succeeding work

and only one compared interval, also three seconds, was given,

although the subject was ignorant of that fact—the method being thus

similar to that adopted later for the final experiments of Group 2,

described above. Six types of tests were given, the order of

stimulation in the different types being SSS, WWW, SSW, WWS, SWW and

WSS, the subject always knowing which order to expect. For each of

the six types one hundred tests were made on one subject and one

hundred and five on another, in sets of five tests of each type, the

sets being taken in varied order, so that possible contrast effect

should be avoided. The results were practically the same, however, in

whatever order the sets were taken, no contrast effect being

discernible.

The total number of judgments of CT, longer, equal, and shorter, is

given in Table VIII. The experiments on each subject consumed a number

of experiment hours, scattered through several weeks, but the relative

proportions of judgments on different days was in both cases similar

to the total proportions.

TABLE VIII.

ST=CT= 3.0 SECS.

Subject R, 100. Subject P, 105.

L E S d L E S d

SSS 32 56 12 + 20 SSS 16 67 22 - 9

WWW 11 53 36 - 25 WWW 19 72 14 + 5

SSW 6 27 67 - 61 SSW 17 56 32 - 15

WWS 57 36 7 + 50 WWS 37 61 7 + 30

WSS 10 45 45 - 35 WSS 9 69 27 - 18

SWW 3 31 66 - 63 SWW 3 64 33 - 25

By the above table the absolute intensity of the stimulus is clearly

shown to be an important factor in determining the constant error of

judgment, since in both cases the change from SSS to WWW changed

the sign of the constant error, although in opposite directions. But

the effect of the relative intensity is more obscure. To discover more

readily whether the introduction of a stronger or weaker stimulation

promises a definite effect upon the estimation of the interval which

precedes or follows it, the results are so arranged in Table IX. that

reading downward in any pair shows the effect of a decrease in the

intensity of (1) the first, (2) the second, (3) the third, and (4) all

three stimulations.

TABLE IX.

Subject R. Subject P.

(1) SSS + 20 - 6

WSS - 35 - 55 - 18 - 12

SWW - 63 - 25

WWW - 25 - 38 + 5 + 30

(2) SSW - 61 - 15

SWW - 63 - 2 - 25 + 10

WSS - 35 - 18

WWS + 50 + 85 + 30 - 48

(3) SSS + 20 - 6

SSW - 61 - 81 - 15 - 7

WWS + 50 + 30

WWW - 25 - 75 + 5 - 25

(4) SSS + 20 - 6

WWW - 15 - 35 + 5 + 11

There seems at first sight to be no uniformity about these results.

Decreasing the first stimulation in the first case increases, in the

second case diminishes, the comparative length of the first interval.

We get a similar result in the decreasing of the second stimulation.

In the case of the third stimulation only does the decrease produce a

uniform result. If, however, we neglect the first pair of (3), we

observe that in the other cases the effect of a difference between

the two stimulations is to lengthen the interval which they limit. The

fact that both subjects make the same exception is, however, striking

and suggestive of doubt. These results were obtained in the first

year’s work, and to test their validity the experiment was repeated at

the beginning of the present year on three subjects, fifty series

being taken from each, with the results given in Table X.

TABLE X.

ST = 3.0 secs. = CT.

Subject Mm. Subject A. Subject D.

S E L d S E L d S E L d

SSS 24 13 13 - 11 7 30 13 + 6 10 31 9 - 1

WSS 33 9 8 - 25 20 24 6 - 14 17 27 6 - 11

SSW 19 15 16 - 3 23 16 11 - 12 10 31 9* - 1

WWW 19 12 19 0 13 26 11 - 2 1 40 9 + 8

SWW 18 30 2 - 16 23 21 6* - 17 7 38 5 - 2

WWS 13 16 21 + 8 12 30 8 - 4 15 25 10 - 5

*Transcriber’s Note: Original “16” changed to “6”, “19” to “9”.

Analysis of this table shows that in every case a difference between

the intensities of the first and second taps lengthens the first

interval in comparative estimation. In the case of subject Mm a

difference in the intensities of the second and third taps lengthens

the second interval subjectively. But in the cases of the other two

subjects the difference shortens the interval in varying degrees.

The intensity difference established for the purposes of these

experiments was not great, being less than that established for the

work on the first two subjects, and therefore the fact that these

results are less decided than those of the first work was not

unexpected. The results are, however, very clear, and show that the

lengthening effect of a difference in intensity of the stimulations

limiting an interval has its general application only to the first

interval, being sometimes reversed in the second. From the combined

results we find, further, that a uniform change in the intensity of

three stimulations is capable of reversing the direction of the

constant error, an intensity change in a given direction changing the

error from positive to negative for some subjects, and from negative

to positive for others.

III. INTERPRETATION OF RESULTS.

We may say provisionally that the change from a tactual stimulation

of one kind to a tactual stimulation of another kind tends to lengthen

subjectively the interval which the two limit. If we apply the same

generalization to the other sensorial realms, we discover that it

agrees with the general results obtained by Meumann[15] in

investigating the effects of intensity changes upon auditory time, and

also with the results obtained by Schumann[16] in investigations with

stimulations addressed alternately to one ear and to the other.

Meumann reports also that the change from stimulation of one sense to

stimulation of another subjectively lengthens the corresponding

interval.

[15] op. cit. (II.), S. 289-297.

[16] op. cit., S. 67.

What, then, are the factors, introduced by the change, which produce

this lengthening effect? The results of introspection on the part of

some of the subjects of our experiments furnish the clue which may

enable us to construct a working hypothesis.

Many of the subjects visualize a time line in the form of a curve. In

each case of this kind the introduction of a change, either in

intensity or location, if large enough to produce an effect on the

time estimation, produced a distortion on the part of the curve

corresponding to the interval affected. All of the subjects employed

in the experiments of Group 2 were distinctly conscious of the change

in attention from one point to another, as the two were stimulated

successively, and three of them, Hy, Hs and P, thought of

something passing from one point to the other, the representation

being described as partly muscular and partly visual. Subjects Mr

and B visualized the two hands, and consciously transferred the

attention from one part of the visual image to the other. Subject Mr

had a constant tendency to make eye movements in the direction of the

change. Subject P detected these eye movements a few times, but

subject B was never conscious of anything of the kind.

All of the subjects except R were conscious of more or less of a

strain, which varied during the intervals, and was by some felt to

be largely a tension of the chest and other muscles, while others felt

it rather indefinitely as a ‘strain of attention.’ The characteristics

of this tension feeling were almost always different in the second

interval from those in the first, the tension being usually felt to be

more constant in the second interval. In experiments of the third

group a higher degree of tension was felt in awaiting a light tap than

in awaiting a heavy one.

Evidently, in all these cases, the effect of a difference between

two stimulations was to introduce certain changes in sensation

during the interval which they limited, owing to the fact that the

subject expected the difference to occur. Thus in the third group of

experiments there were, very likely, in all cases changes from

sensations of high tension to sensations of lower, or vice versa. It

is probable that, in the experiments of the second group, there were

also changes in muscular sensations, partly those of eye muscles,

partly of chest and arm muscles, introduced by the change of attention

from one point to another. At any rate, it is certain that there were

certain sensation changes produced during the intervals by changes of

locality.

If, then, we assume that the introduction of additional sensation

change into an interval lengthens it, we are led to the conclusion

that psychological time (as distinguished from metaphysical,

mathematical, or transcendental time) is perceived simply as the

quantum of change in the sensation content. That this is a true

conclusion is seemingly supported by the fact that when we wish to

make our estimate correspond as closely as possible with external

measurements, we exclude from the content, to the best of our ability,

the general complex of external sensations, which vary with extreme

irregularity; and confine the attention to the more uniformly varying

bodily sensations. We perhaps go even further, and inhibit certain

bodily sensations, corresponding to activity of the more peripherally

located muscles, that the attention may be confined to certain others.