Formation and development of temporary connections involving unperceived and perceived acoustic stimuli.

Abstract

1. In experiments with the simultaneous formation of responses to perceived and unperceived acoustic stimuli, orienting reactions to these stimuli were shown to differ in their time course. Electrographic components appeared in response to the unperceived acoustic stimulus only at the 6th–10th presentation, and later their intensity remained sufficiently high even after 60 presentations of the stimulus; only partial extinction of the components of the orienting reflex took place, as shown by a decrease in the probability of appearance and fall of the amplitude of the galvanic skin response and strengthening and weakening of the power of each individual response of depression of the alpha-rhythm. 2. Asymmetry of depression of spontaneous rhythmic activity and its predominance in the left hemisphere, linked with the conditioned reflex movement observed in these experiments, are evidence of the formation of temporary connections to both perceived and unperceived stimuli. However, formation and the consolidation of the temporary connections to the unperceived acoustic stimulus take place more slowly and become manifested only after 30–40 presentations. 3. The results are evidence in support of the hypothesis of relative independence of the formation of responses to perceived and unperceived stimuli, even of the same nature, and of the accelerating influence of the second signal system during the formation of conditioned reflex responses to perceived stimuli.