The relationship between the strength of the conditioned stimulus and the size of the resulting conditioned reflex / by P.S. Kupalov and W. Horsley Gantt.

  • Kupalov, P. S. (Petr Stepanovich), 1888-
Date:
[1926?]
Catalogue details

Licence: In copyright

Credit: The relationship between the strength of the conditioned stimulus and the size of the resulting conditioned reflex / by P.S. Kupalov and W. Horsley Gantt. Source: Wellcome Collection.

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    tactile and thermal analysers cannot produce so strong a process of excitation as those of the auditory analysers, and that they more readily pass over into a state of inhibition. Such a view lacks experimental verification. Certain observations suggest that the difference depends solely upon the strength of the stimulus, upon the amount of energy sent into the cortex. To investigate this problem we employed complex stimuli affecting several analysers. It was already known that in the reaction to a complex of two simultaneous stimuli the chief effect was produced by one of the components, that of the other being suppressed, so that the latter did not produce the reaction which it would have done had it been employed alone. If we assume that the magnitude and stability of the conditioned reflexes to auditory stimuli when compared with the responses to cutaneous and optical stimuli depend, not upon a qualitative difference in the nervous processes concerned, but upon quantitative- factors, then we may experimentally vary the latter, comparing, for example, the effect of weak auditory and strong optical stimuli. If quantitative factors govern the response, then we should obtain a greater response to strong light than to weak auditory stimuli. Further, if our supposition is true, these two stimuli might be so adjusted as to produce equal reflex responses. The observations recorded in the present paper were based upon such an hypothesis. Observations had already been made in the laboratory relating to this problem, but being directed to other purposes, did not provide the facts which were of primary interest to us. Thus, Palladin [4] formed a conditioned reflex by the summation of stimuli (simultaneous thermal —cold—with scratching stimuli). When each component was separately employed it was found that a response equal to that obtained on combina¬ tion of the two resulted from scratching, while cold alone gave either no response or a minimal one. However, the continued use of cold as a stimulus finally evoked a constant response, but one less than that elicited by scratching. Thus in a complex of qualitatively different stimuli the response depends upon the more potent stimulus. Perlzweig [5] confirmed these observations. We have extended them to include auditory and optical, auditory and thermal combinations. In one dog we formed a conditioned reflex to a faint sound (Galton’s whistle) applied simultaneously with a strong light (400 candle-power), crv Oacj; the sound of the whistle being muffled by placing it in a large bottle so that it was scarcely audible to the human ear at 40 cm. distance from