Abstract
The present paper is the second report on the experimental studies, which were designed to elucidate animal's behavior in relation to the goal.
Approach behavior: The Ss used in the first experiment were ten guinea pigs. They were thoroughly trained to run for food from the right end to the left end of the alley. After the training trials, tests were made to determine the strength of pull they would exert when food was removed from them at different points in the alley, under 23-hour food deprivation. In this situation, the right end of the alley does not acquire the character of the starting point. The results are shown in Fig. 5. It was found that the approach gradient was a negative growth function of the distance from the goal, that is, the animals pulled harder the nearer they were to it. But, a question rises whether it is really a goal gradient. In order to make this point clear, an additional experiment was designed under the situation under which the number of passages was equalized at each point in the alley. The results are presented in Fig. 6. A comparison of the curves of Fig. 5 and Fig. 6 indicates that the gradient of Fig. 5 was not based upon the difference in the number of passages at each point, but the effect of the goal as a function of the distance between the subject and the goal.
The second experiment was designed to investigate the approach gradient as a function of drive level, under 4-, 12-, 23- and 36- hour food deprivation. After five animals had been trained to run down the alley to secure the food separated from them, they were tested for strength of pull under different drive levels. The heights of the gradients, as can be seen in Fig. 8, vary with the strength of drive.
Escape behavior: The third experiment was designed to investigate the escape gradient as a function of the distance from the point at which the animals received a shock and the effect of the strength of the shock upon the gradient. The Ss used in this experiment were fifteen guinea pigs, and they were divided into three groups by shock intensity given, that is, 8-volt group, 20-volt group and 32-volt group. They were tested for strength of pull at different distances from the point at which the shock was administered. The results are presented in Fig. 13. The animals pulled harder the nearer they were to the shock point. That is, the escape gradient is a negative growth function of the distance from the shock. The heights of the gradients vary with the strength of the shock. Besides, a comparison of the results of approach and escape behaviors indicates that the escape gradient is steeper than the approach gradient.
