Sympathetic Activity and Perception

Abstract

Psychological activity, such as the perception of a fearful object, can evoke autonomic changes. The inverse of this operation, however, is poorly understood. How, if at all, does autonomic activity influence psychological activity? An hypothesis is presented concerning an effect of autonomic activity on personality which is in essence an inverse feedback concept. If awareness of and reaction to a threat induce a sympathetic discharge, then sympathetic activity should have an inverse effect on awareness of cues. This postulated decrease in awareness and reactivity was termed decreased extroceptive input, and was tested by observing changes in visual perception produced by increased endogenous sympathetic activity. Using both a cold-pressor procedure and amyl nitrite inhalations to induce sympathetic activity, a consistent decrease in the apparent size of a distant object relative to a nearer object was observed. Evidence was presented to demonstrate that this was not due to local ophthal-mic effects nor to decreased attention, but rather, was explainable on the basis of decreased size constancy which could result from a narrowed awareness with reduction of reaction to distance cues. This fits the hypothesis of decreased extroceptive input. The literature of behavioral correlates of autonomic activity is reviewed and additional evidence in support of this hypothesis is pointed out. The implication of such a notion for the study of normal and pathological states is discussed.