Average Evoked Potentials and Reaction times to Visual Stimuli

Average evoked potentials to brief light flashes were recorded from occipital, vertex, temporal and orbital leads in ten subjects during a reaction time study. Subjects performed under two conditions, with and without knowledge of results. The amplitude of the average evoked potentials was related to reaction time. For any given sequence of reaction times, faster reactions were associated with larger amplitude average evoked potentials. Knowledge of results shortened reaction times and increased the magnitude of average evoked potentials. The diffuse and non-specific character of the main component of the average evoked potential appears to reflect changes in cortical excitability associated with the variability of reaction time. This result has been interpreted in relation to the non-specific arousal and alerting mechanism