The time of perception as a measure of differences in sensations / by Vivian Allen Charles Henmon.

  • Henmon, Vivian Allen Charles (V. A. C.), 1877-
Date:
1906
Catalogue details

Licence: In copyright

Credit: The time of perception as a measure of differences in sensations / by Vivian Allen Charles Henmon. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    The history of mental measurement shows that two apparently independent lines of research in psychology have been pursued with a diligence rarely if ever equaled in the history of any science. On the one hand is the measurement of the time-relations of mental phenom- ena; on the other, the measurement of the relation of the stimulus to the sensation, the psychophysical law, which has concerned itself chiefly with relations of intensity. These lines of inquiry, mental time and mental intensity, appear to converge in the method here applied, one mental quantity being used as a measure of the other. The method proposes the use of mental time to measure mental in- tensity. It would, therefore, be in place to consider the history of the measurement of these quantities, which has run a parallel and in- dependent course with occasional evidences of interrelations and points of contact. However, it would carry us too far afield to give a detailed account of the investigations of reaction-times, or, more particularly, that part of the work which has to do with perception- and will-time, or, as it is perhaps more often termed, the time of dis- crimination and choice. This would bear more or less directly on this study. Again, the method here used and the results obtained bear directly on the problems of psychophysics, an account of which is beyond the limits of this paper. Summaries there are in plenty, and a detailed account is here out of the question. I shall content myself with giving, after some introductory considerations, a historical account of the psychometric method as a measure of differences in sensations. From the measurement of the velocity of the nerve impulse by Helmholtz in 1850 it was not a far cry to the determination of the time of reaction, or the time elapsing between the giving of the stimulus and the execution of an appropriate and predetermined movement. . The elements that enter into the processes which take place have been variously analyzed, and attempts have been made to isolate them for purposes of determining especially the time taken up by the purely cerebral processes. There is the time taken to overcome the inertia of the sense organs, the time of centrifugal and centripetal conductions in the sensory and motor nerves and in the cord, and the latent time of a muscle. Moreover, the factors which influence the reaction-time, such as the quality and intensity of the stimulus, the effects of practise, fatigue, attention, mode of reaction, and racial and individual differ- ences, have been studied in detail. The simple reaction-time, aside from the analysis of the conditions above noted, is of especial interest and value from the fact that there
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