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Harvard Psychological Studies, Volume 1 eBook

This eBook from the Gutenberg Project consists of approximately 678 pages of information about Harvard Psychological Studies, Volume 1.
such stimuli as light and the relation of the opening to the place at which the animals were put into the box might in themselves be sufficient to direct the animals to this point without the help of any associations which had resulted from previous experience, makes it unsatisfactory.  In addition to the possibility of the action being due to specific sensory stimuli of inherent directive value, there is the chance of its being nothing more than the well-known phenomenon of repetition.  Frogs, for some reason, tend to repeat any action which has not proved harmful or unpleasant.

For the purpose of more carefully testing this kind of association, a small box with an opening 15 cm. by 10 cm. was arranged so that the animal could escape from confinement in it through the upper part of the opening, the lower portion being closed by a plate of glass 10 cm. by 10 cm., leaving a space 5 cm. by 10 cm. at the top.  One subject placed in this box escaped in 5 minutes 42 seconds.  After 5 minutes’ rest it was given another trial, and this time got out in 2 minutes 40 seconds.  The times for a few subsequent trials were:  Third, 1 minute 22 seconds; fourth, 4 minutes 35 seconds; fifth, 2 minutes 38 seconds; sixth, 3 minutes 16 seconds.  Although this seems to indicate some improvement, later experiments served to prove that the frogs did not readily form any associations which helped them to escape.  They tended to jump toward the opening because it was light, but they did not learn with twenty or thirty experiences that there was a glass at the bottom to be avoided.  Thinking that there might be an insufficient motive for escape to effect the formation of an association, I tried stimulating the subject with a stick as soon as it was placed in the box.  This frightened it and caused violent struggles to escape, but instead of shortening the time required for escape it greatly lengthened it.  Here was a case in which the formation of an association between the appearance of the upper part of the clear space and the satisfaction of escape from danger would have been of value to the frog, yet there was no evidence of adaptation to the new conditions within a reasonably short time.  There can be little doubt that continuation of the training would have served to establish the habit.  This very clearly shows the slowness of adaptation in the frog, in contrast with the rapidity of habit formation in the cat or chick; and at the same time it lends additional weight to the statement that instinctive actions are all-important in the frog’s life.  A few things it is able to do with extreme accuracy and rapidity, but to this list new reactions are not readily added.  When put within the box described, an animal after having once escaped would sometimes make for the opening as if it knew perfectly the meaning of the whole situation, and yet the very next trial it would wander about for half an hour vainly struggling to escape.

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