Activation and Behavior: II. Visually Evoked Cortical Potentials in Man as Indicants of Activation Level

Abstract

The effects of variations in behavioral arousal and neural activation or excitation on averaged evoked occipital-cortical potentials to a repetitive flashing light stimulus were studied, using the Mnemotron computer of average transients (CAT). Degree of behavioral arousal and neural activation was manipulated by having Ss perform physical and “mental” tasks of varying degrees of difficulty. Records obtained under these conditions were compared with those obtained during periods of physical and mental quiescence wherein activation level was assumed to be at a relatively low level. The evoked potential patterns were found to increase in amplitude and/or to change in wave form with increases in level of activation or arousal. A number of techniques for quantifying differences in evoked cortical potential patterns were described. It was concluded that the evoked potential measure may be added to the repertory of physiological measures (EEG, EMG, heart rate, skin conductance, etc.) currently considered to constitute reliable and valid indices of activation level.