Cephalic and digital vasomotor orienting responses: the effect of response localization, stimulus type and stimulus repetition.

Two studies are reported; the first dealing with vascular responses in the head area and in finger to tone, bell and mental arithmetic stimuli, the second, with the same responses to a series of 20 tones. Dilation responses from the head area were considerably less frequently obtained to pure tone than the other three stimuli, even on first exposure. This may account for some of the disparities in results between Eastern and Western European investigators. Habituation to tone from the head, and to a lesser extent from the finger, involved a shift from vasodilative to vasoconstrictive responses. However, a series of 20 tones was not sufficient to demonstrate habituation of the vasoconstrictive response. The shift from vasodilative to vasoconstrictive responses from the head area is not concordant with Sokolovian notions of the latter response being associated with defensive responses, unless one considers the possibility that the experimental situation becomes aversive over the experimental period. This possibility is explored in the paper.