The orienting response as a nonverbal measure of neurological extinction.

Abstract

Detection and localization of tactile stimulation in neurological patients is typically evaluated through verbal report. This approach is limited, especially in evaluating perceptual distortions, some of which may have a primarily psychological rather than physiological explanation. An alternative approach, based on the orienting response as measured by the galvanic skin response (GSR), was evaluated for its equivalence to verbal report. Its efficacy was explored in measuring face-hand extinction in which sensation on the hand is masked when face and hand are touched simultaneously. The GSR to single stimulations of the cheek was habituated and then simultaneous stimulation of the cheek and hand was given. Ss were dichotomized on the basis of their verbal report as to whether they reported feeling the touch on the hand. The 12 Ss reporting only face stimulation (extinction), showed no new orienting response, but a large response was evoked in 12 Ss reporting both touches. This measure might provide basic insight into paradoxical clinical phenomena such as hysterical anesthesia, allesthesia, and unilateral right-left disorientation.