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

point, with side excursions to right and left, when refreshment of

perception is needed. The balance is horizontal and not vertical.

C. A balance with variety, or without symmetry. Centers at division

point and wants sweep over long part. More concentration on short

part. Subjective activity there—an introduction of energy. A

contraction of the muscles used in active attention. Long side easier,

takes care of itself, self-poised. Line centers at division point.

Active with short division. Introduces activity, which is equivalent

to the filling that the complex figures have; in these the introduced

activity is objectified—made graphic.

D. Focal point at division point: wants the interesting things in a

picture to occupy the left (when short division is also on left).

Short division the more interesting and means greater complication.

When the pleasing division is made, eyes move first over long and then

over short. Division point the center of real reference from which

movements are made.

E. No reference to center in making judgments; hurries over center.

All portions of simple line of equal interest; but in unequal division

the short gets a non-apparent importance, for the line is then a

scheme for the representation of materials of different interest

values. When the division is too short, the imagination refuses to

give it the proportionally greater importance that it would demand.

When too long it is too near equality. In enjoying line, the division

point is fixed, with shifts of attention from side to side. An

underlying intellectual assignment of more value to short side, and

then the sense-pleasure comes; the two sides have then an equality.

F. Middle vulgar, common, prosaic; unequal lively. Prefers the

lively. Eyes rest on division point, moving to the end of long and

then of short. Ease, simplicity and restfulness are proper to the long

part of complex figures. Short part of simple line looks wider,

brighter and more important than long.

G. Unequal better than equal. Eye likes movement over long and then

over short. Subject interested only in division point. Short part

gives the æsthetic quality to the line.

H. Center not wanted. Division point the center of interest. (No

further noteworthy introspection from H, but concerning complex

figures he said that he wanted simple or the compact on the short, and

the interesting on the long.)

These introspective notes were given at different times, and any

repetitions serve only to show constancy. The subjects were usually

very certain of their introspection. In general it appears to me to

warrant these three statements: (1) That the center of interest is the

division point, whence eye-movements, or innervations involving,

perhaps, the whole motor system, are made to either side. (2) That

there is some sort of balance or equivalence obtained (a bilateral

symmetry), which is not, however, a vertical balance—that is, one of

weights pulling downwards, according to the principle of the lever.

All the subjects repudiated the suggestion of vertical balance. (3)

That the long side means ease and simplicity, and represents

graphically exactly what it means; that the short side means greater

intensity, concentration, or complexity, and that this is substituted

by the subject; the short division, unlike the long, means something

that it does not graphically represent.

So much for the relation between what is objectively given and the

significance subjectively attributed to it. There remains still the

translation into psychophysical terms. The results on the complex

figures (showing that a division may be shortened by making the

innervations on that side increasingly more involved) lend

plausibility to the interpretation that the additional significance

is, in visual terms, a greater intricacy or difficulty of

eye-movement, actual or reproduced; or, in more general terms, a

greater tension of the entire motor system. In such figures the

psychophysical conditions for our pleasure in the unequal division of

the simple horizontal line are merely graphically symbolized, not

necessarily duplicated. On page 553 I roughly suggested what occurs in

regarding the unequally divided line. More exactly, this: the long

section of the line gives a free sweep of the eyes from the division

point, the center, to the end; or again, a free innervation of the

motor system. The sweep the subject makes sure of. Then, with that as

standard, the æsthetic impulse is to secure an equal and similar

movement, from the center, in the opposite direction. It is checked,

however, by the end point of the short side. The result is the

innervation of antagonistic muscles, by which the impression is

intensified. For any given subject, then, the pleasing unequal

division is at that point which causes quantitatively equal

physiological discharges, consisting of the simple movement, on one

hand, and, on the other, the same kind of movement, compounded with

the additional innervation of the antagonists resulting from the

resistance of the end point. Since, when the characteristic movements

are being made for one side, the other is always in simultaneous

vision, the sweep receives, by contrast, further accentuation, and the

innervation of antagonists doubtless begins as soon as movement on the

short side is begun. The whole of the short movement is, therefore,

really a resultant of the tendency to sweep and this necessary

innervation of antagonists. The correlate of the equivalent

innervations is equal sensations of energy of movement coming from the

two sides. Hence the feeling of balance. Hence (from the lack of

unimpeded movement on the short side) the feeling there of

‘intensity,’ or ‘concentration,’ or ‘greater significance.’ Hence,

too, the ‘ease,’ the ‘simplicity,’ the ‘placidity’ of the long side.

As in traditional symmetry, the element of unity or identity, in

unequal division, is a repetition, in quantitative terms, on one side,

of what is given on the other. In the simple line the equal division

gives us obviously exact objective repetition, so that the

psychophysical correlates are more easily inferred, while the

unequal offers apparently no compensation. But the psychophysical

contribution of energies is not gratuitous. The function of the

increment of length on one side, which in the centrally divided line

makes the divisions equal, is assumed in unequal division by the end

point of the short side; the uniform motor innervations in the former

become, in the latter, the additional innervation of antagonists,

which gives the equality. The two are separated only in degree. The

latter may truly be called, however, a symmetry of a higher order,

because objectively the disposition of its elements is not graphically

obvious, and psychophysically, the quantitative unity is attained

through a greater variety of processes. Thus, in complex works of art,

what at first appears to be an unsymmetrical composition, is, if

beautiful, only a subtle symmetry. There is present, of course, an

arithmetically unequal division of horizontal extent, aside from the

filling. But our pleasure in this, without filling, has been seen to

be also a pleasure in symmetry. We have, then, the symmetry of equally

divided extents and of unequally divided extents. They have in common

bilateral equivalence of psychophysical processes; the nature of these

differs. In both the principle of unity is the same. The variety

through which it works is different.

*

STUDIES IN ANIMAL PSYCHOLOGY.

*

HABIT FORMATION IN THE CRAWFISH CAMBARUS AFFINIS.[1]

BY ROBERT M. YERKES AND GURRY E. HUGGINS.

[1] See also Yerkes, Robert: ‘Habit-Formation in the Green

Crab, Carcinus Granulalus,’ Biological Bulletin, Vol. III.,

1902, pp. 241-244.

This paper is an account of some experiments made for the purpose of

testing the ability of the crawfish to profit by experience. It is

well known that most vertebrates are able to learn, but of the

invertebrates there are several classes which have not as yet been

tested.

The only experimental study of habit formation in a crustacean which

we have found is that of Albrecht Bethe[2] on the crab, _Carcinus

maenas_. In his excellent paper on the structure of the nervous system

of Carcinus Bethe calls attention to a few experiments which he made

to determine, as he puts it, whether the crab possesses psychic

processes. The following are the observations made by him. Experiment

I. A crab was placed in a basin which contained in its darkest corner

an Eledone (a Cephalopod). The crab at once moved into the dark

region because of its instinct to hide, and was seized by the

Eledone and drawn under its mantle. The experimenter then quickly

freed the crab from its enemy and returned it to the other end of the

basin. But again the crab returned to the dark and was seized. This

was repeated with one animal five times and with another six times

without the least evidence that the crabs profited by their

experiences with the Eledone. Experiment 2. Crabs in an aquarium

were baited with meat. The experimenter held his hand above the food

and each time the hungry crab seized it he caught the animal and

maltreated it, thus trying to teach the crabs that meat meant danger.

But as in the previous experiment several repetitions of the

experience failed to teach the crabs that the hand should be avoided.

From these observations Bethe concludes that Carcinus has no

‘psychic qualities’ (i.e., is unable to profit by experience), but

is a reflex machine.

[2] Bethe, Albrecht: ‘Das Centralnervensystem von _Carcinus

maenas_,’ II. Theil., Arch. f. mikr. Anat., Bd. 51, 1898, S.

Bethe’s first test is unsatisfactory because the crabs have a strong

tendency to hide from the experimenter in the darkest corner. Hence,

if an association was formed, there would necessarily be a conflict of

impulses, and the region in which the animal would remain would depend

upon the relative strengths of its fear of the experimenter and of the

Eledone. This objection is not so weighty, however, as is that which

must obviously be made to the number of observations upon which the

conclusions are based. Five or even twenty-five repetitions of such an

experiment would be an inadequate basis for the statements made by

Bethe. At least a hundred trials should have been made. The same

objection holds in case of the second experiment. In all probability

Bethe’s statements were made in the light of long and close

observation of the life habits of Carcinus; we do not wish,

therefore, to deny the value of his observations, but before accepting

his conclusions it is our purpose to make a more thorough test of the

ability of crustaceans to learn.

[Illustration: FIG. 1. Ground Plan of Labyrinth. T, triangular

compartment from which animal was started; P, partition at exit;

G, glass plate closing one exit passage. Scale 1/6.]

For determining whether the crawfish is able to learn a simple form of

the labyrinth method was employed. A wooden box (Fig. 1) 35 cm. long,

24 cm. wide and 15 cm. deep, with one end open, and at the other end

a triangular compartment which communicated with the main portion of

the box by an opening 5 cm. wide, served as an experiment box. At the

open end of this box a partition (P) 6 cm. long divided the opening

into two passages of equal width. Either of these passages could be

closed with a glass plate (G), and the subject thus forced to escape

from the box by the choice of a certain passage. This box, during the

experiments, was placed in the aquarium in which the animals lived. In

order to facilitate the movement of the crawfish toward the water, the

open end was placed on a level with the water in the aquarium, and the

other end was raised so that the box made an angle of 6°