Intensity differences of sensations / by Charles S. Myers.

  • Charles Samuel Myers
Date:
[between 1924 and 1929?]
Catalogue details

Licence: In copyright

Credit: Intensity differences of sensations / by Charles S. Myers. Source: Wellcome Collection.

    5/88 (page 3)
    In recent years, however, this simple system of physiolo? gical correlations has been breaking down. All nerves seem to be alike and to be but passive conductors. We still speak of their specific energies, but we mean now a specificity ’of locus in their central terminations. This view of quality, however, conflicts with the theory of extensity. It is hard to believe, for example, that the difference between red and blue is a difference of locus in the occipital cortex, when local differences have already been appropriated for visual space perception. This difficulty is emphasized by recent negative work on cerebral localization of function, and is doubtless one factor that operates toward frequency theories of sensory quality. Moreover, the progress of physiological research has. created a difficulty, not only for quality, but also for intensity where the psychologist had thought himself most secure. The alhormothing principle of Adrian and Lucas makes it seem improbable that nerve fibers can conduct with different degrees of excitation; and Forbes and others have shown that the principle holds for sensory nerves as well as motor nerves. 0 Does this discovery shake our faith in the intensity of sensation? Forbes and Gregg have sought to restore the faith by an appeal to the variable excitation of nerve^fiber during the relative refractory period. A sustained stimulus may give rise to a repetitive discharge of the nerve. The stimulus begins by initiating a first discharge which leaves the nerve inactive during the absolute refractory period. When the relative refractory period sets in, the excitability of the nerve gra? dually returns until, if the stimulus is being continued, exci^ tability reaches a point where stimulus becomes adequate and there is a second discharge. Then, as long as the stimulus Cf., e.g., S. I. Franz, Science, 1912, N. S. 35, 321—328; Psychol. Rev., 1921, 28, 81—95; Franz and K. S. Lashley, Psychobiology, 1917, 1, 3—18, 71—139; etc. Cf. K. Lucas, Conduction of the Nervous Impulse, 1917. *) A. Forbes and A. Gregg, Am. J. Physiol., 1915, 39, 172—235; E. D. Adrian and Forbes, J. Physiol., 1922, 56, 301—330.