The Coding of Direction of Tactile Stimulus Movement: Correlative Psychophysical and Electrophysiological Data

Recently published psychophysical studies have shown that the capacity of human subjects to identify direction of tactile stimuli that move in a linear path across the thenar eminence and the upper arm is a function of velocity, of the distance traversed by the moving stimulus (“traverse length”) and of the cutaneous innervation density (Dreyer, Hollins, and Whitsel, 1976; Dreyer, Duncan, and Wong, 1978a; Dreyer, Hollins, and Whitsel, 1978b). Moreover, a subject’s capacity to identify direction of linear movement on either the hairy or glabrous skin is independent of the orientation of the stimulus path (Whitsel and Dreyer, unpublished observations).