Harvard Psychological Studies Part 72

11 to 20 4 times to red 6

Red on Left. White on Right.

21 to 30 3 times to red 7

To Red. To White. To Right. To Left.

Totals. 17 13 23 7

This table indicates in trials 1 to 10 a strong tendency to the red cardboard. Trials 21 to 30 prove that there was also a tendency to the right.

Training was begun with the labyrinth arranged as shown in Fig. 1, that is, with the left entrance pa.s.sage and the right exit pa.s.sage open, and with red cardboard on the right (red was always on the side to be avoided) and white on the left. Table II. contains the results of 110 trials with No. 2, arranged according to right and wrong choice at the entrance and exit. Examination of this table shows a gradual and fairly regular increase in the number of right choices from the first series to the last; after 100 experiences there were practically no mistakes.

With another subject, No. _6a_, the results of Table III. were obtained. In this instance the habit formed more slowly and to all appearances less perfectly. Toward the end of the second week of work _6a_ showed signs of sickness, and it died within a few weeks, so I do not feel that the experiments with it are entirely trustworthy. During the experiments it looked as if the animal would get a perfectly formed habit very quickly, but when it came to the summing up of results it was obvious that there had been little improvement.

[Ill.u.s.tration: FIG. 2. Labyrinth as arranged for experiments. _E_, entrance; _R, R_, regions covered with red; _W, W_, regions covered with white. The tracing represents the path taken by No. 2 on the sixth trial. Dots mark jumps.]

TABLE II.

LABYRINTH HABIT. FROG NO. 2.

Entrance. Exit. Remarks.

Trials. Right. Wrong. Right. Wrong.

1- 10 1 9 4 6 One day rest.

11- 20 2 8 5 5 21- 30 4 6 7 3 31- 40 5 5 6 4 41- 50 5 5 6 2 (17) (33) (30) (20) 51- 60 9 1 8 2 61- 70 6 4 10 0 71- 80 7 3 9 1 81- 90 9 1 8 2 91-100 10(50) 0(10) 10(52) 0( 8) --- --- --- --- 67 43 82 28

Other animals which were used gave results so similar to those for frog No. 2 that I feel justified in presenting the latter as representative of the rapidity with which the green frog profits by experience.

TABLE III.

LABYRINTH HABIT. FROG NO. _6a_.

Entrance. Exit. Remarks.

Trials Right. Wrong. Right. Wrong.

1- 10 6 4 5 5 One day rest.

11- 20 7 3 4 6 21- 30 2 8 1 9 31- 40 6 4 1 9 41- 50 7 3 8 2 (28) (22) (19) (31) 51- 60 5 5 7 3 61- 70 6 4 4 6 71- 80 4 6 3 7 One day rest.

81- 90 5 5 7 3 91-100 10(30) 0(20) 8(29) 2(21) ---- ---- ---- ---- (58) (44) (48) (52)

Preliminary Trials.

Red on Left Part.i.tion at Exit on Right 1- 5 5 times to Red 4 times to Part.i.tion.

Red on Right Part.i.tion at Exit on Left 6-10 3 times to Red 5 times to Part.i.tion.

2. _Rapidity of Habit Formation_.--As compared with other vertebrates whose rapidity of habit formation is known, the frog learns slowly.

Experimental studies on the dog, cat, mouse, chick and monkey furnish excellent evidence of the ability of these animals to profit quickly by experience through the adapting of their actions to new conditions.

They all show marked improvement after a few trials, and after from ten to thirty most of them have acquired perfect habits. But the comparison of the frog with animals which are structurally more similar to it is of greater interest and value, and we have to inquire concerning the relation of habit formation in the frog to that of fishes and reptiles. Few experimental studies with these animals have been made, and the material for comparison is therefore very unsatisfactory. E.L. Thorndike[1] has demonstrated the ability of fishes to learn a labyrinth path. In his report no statement of the time required for the formation of habit is made, but from personal observation I feel safe in saying that they did not learn more quickly than did the frogs of these experiments. Norman Triplett[2] states that the perch learns to avoid a gla.s.s part.i.tion in its aquarium after repeatedly b.u.mping against it. Triplett repeated Moebius' famous experiment, and found that after a half hour's training three times a week for about a month, the perch would not attempt to capture minnows which during the training periods had been placed in the aquarium with the perch, but separated from them by a gla.s.s part.i.tion. Triplett's observations disprove the often repeated statement that fishes do not have any a.s.sociative processes, and at the same time they show that the perch, at least, learns rapidly--not so rapidly, it is true, as most animals, but more so in all probability than the amphibia.

[1] Thorndike, Edward: 'A Note on the Psychology of Fishes,'

_American Naturalist_. 1899, Vol. x.x.xIII., pp. 923-925.

[2] Triplett, Norman: 'The Educability of the Perch,' _Amer.

Jour. Psy._, 1901, Vol. XII., pp. 354-360.

The only quant.i.tative study of the a.s.sociative processes of reptiles available is some work of mine on the formation of habits in the turtle.[3] In the light of that study I can say that the turtle learns much more rapidly than do fishes or frogs. Further observations on other species of turtles, as yet unpublished, confirm this conclusion.

[3] Yerkes, Robert Mearns: 'The Formation of Habits in the Turtle,' _Popular Science Monthly_, 1901, Vol. LVIII., pp.

519-535.

For the frog it is necessary to measure and calculate the improvement in order to detect it at first, while with the turtle or chick the most casual observer cannot fail to note the change after a few trials. In connection with the quickness of the formation of a.s.sociations it is of interest to inquire concerning their permanency.

Do animals which learn slowly retain a.s.sociations longer? is a question to which no answer can as yet be given, but experiments may readily be made to settle the matter. I have tested the frog for permanency, and also the turtle, but have insufficient data for comparison.

3. _Sensory Data Contributing to the a.s.sociations_.--Among the most important of the sensory data concerned in the labyrinth habit are the visual impressions received from the different colored walls, the slight differences in brightness of illumination due to shadows from the part.i.tions and the contrast in form of the two sides of the labyrinth resulting from the use of the part.i.tions, and the muscular sensations dependent upon the direction of turning. The experiments proved beyond question that vision and the direction of turning were the all-important factors in the establishment of the habit. At first it seemed as if the direction of turning was the chief determinant, and only by experimenting with colors under other conditions was I able to satisfy myself that the animals did notice differences in the appearance of their surroundings and act accordingly. In Table IV.

some results bearing on this point have been arranged. To begin with, the habit of going to the left when the red was on the right at the entrance had been established; then, in order to see whether the colors influenced the choice, I reversed the conditions, placing the red on the left, that is, on the open-pa.s.sage side. The results as tabulated in the upper part of Table IV. show that the animals were very much confused by the reversal; at the entrance where there were several guiding factors besides the colors there were 50 per cent. of mistakes, while at the exit where there were fewer differences by which the animal could be directed it failed every time. This work was not continued long enough to break up the old habit and replace it by a new one, because I wished to make use of the habit already formed for further experiments, and also because the animals remained so long in the labyrinth trying to find their way out that there was constant danger of losing them from too prolonged exposure to the dry air.

TABLE IV.

INFLUENCE OF CHANCES OF CONDITIONS. FROG NO. 2.

Habit perfectly formed of going to Left (avoiding Red) at entrance and to Right at exit. Conditions now reversed. Red on Left. Part.i.tion at Exit on Right.

Trials. Entrance. Exit. Remarks.

Right. Wrong. Right. Wrong.

1- 5 3 2 0 5 6-10 2 3 0 5

Discontinued because animal remained so long in labyrinth that there was danger of injuring it for further work. This shows that the habit once formed is hard to change.

Given 20 trials with conditions as at first in order to establish habit again.

1-10 9 1 8 2 11-20 10 0 9 1

Colors reversed, no other change. To test influence of colors.

1-10 6 4 10 0

INFLUENCE OF DISTURBANCE WHEN ANIMAL IS ENTERING BOX.

No Disturbance. Animal Touched.

To Red (Right). To White (Left). To Red. To White.

2 8 5 5

This was after the tendency to go to the Left at the entrance had been established.