Section 34
Chapter 33,533

Studies of the conditioned reflex in the lower vertebrates III Motor-food conditioned reflex in domestic fowls

Koga, K.

Science Reports of the Tohoku University, Series 4. Biology 22: 115-136


ISSN/ISBN: 0040-8786
Accession: 033532459

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Motor food conditioned reflexes have been studied by combining food with light (green and red) as a conditioned stimulus in chickens (ages 27 to 175 days after hatching). The speed and retention of the temporary connection did not seem to be related to the colors employed, nor to the sex and age of the chickens. At the first application of the differential stimulus, marked variations were found among individual chickens. The difference between the sexes was especially distinct. According to the amount of generalization and the course of differentiation, the chickens were classified into 3 groups, as follows: (1) The ones in which both the processes of excitation and inhibition were equilibrated; (2) those in which the processes of excitation predominates over that of inhibition; (3) those in which the process of inhibition predominated over that of excitation. The formation of differentiation between colors appeared to be relatively difficult for the chickens. A few of them failed to develop a complete differentiation, because of the disturbance of the nervous activity, or the development of the process of inhibition. Differential inhibition develops much more slowly than the positive conditioned connection. Compared with the retention of the positive conditioned reflex, that of differential inhibition is, to a certain extent, more difficult. The latter decreases quickly after discontinuation of testing for 1 to 3 weeks. Successive changes of signal denotations were made, 5 times at the maximum. By means of these changes it is possible to classify chickens into 3 groups, relative to the type of nervous system, and to the course of differentiation. Throughout the course of changing the signal denotations of stimuli, it was more difficult to establish a negative reflex than a positive one. The greatly increased intersignal reactions, which occur in the early stage of each change of signal denotations, diminish according to the progress of the change. As a rule, the intersignal reactions almost disappear or decrease in frequency during the course of the change. The rate of extinction of the intersignal reactions seems to depend upon the age of the chickens. The latency of reflex reactions to the positive and negative stimuli, respectively, are altered parallel with the changing of the signals. Conditioned reflexes, once formed, were not retained after a 3 months' discontinuation of experiments.

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