Vigilance and Arousal in Depressive States

Abstract

An experiment was performed to investigate predictions of vigilance performance among depressive patients, based on the assumptions that vigilance would vary in a predictable manner with level of arousal, and that levels of arousal among diagnostic categories of depressive patients are well known. It was found that psychotic depressives, presumed to be hypo-aroused relative to normals, exhibited poor signal detection performances and committed few false positive errors relative to normals. This was consistent with predictions. Neurotic depressives, presumed to be hyper-aroused relative to normals, detected fewer signals than did normals, but also made more false positive errors than normals. Again this was consistent with predictions. A measure of arousal in experimental subjects, namely barbiturate tolerance, was found to directly relate to the false positive error rate in all subjects. The relationship between arousal and total signal detection rate was significantly curvilinear, and an 'inverted U' (quadratic) function provided the best fit. This justified the conclusion that vigilance performance is a function of at least that component of arousal measured by barbiturate tolerance.