Neurophysiology of Consciousness

Abstract

Voluntary acts are preceded by electrophysiological “ readiness potentials” (RPs). With spontaneous acts involving no preplanning, the main negative RP shift begins at about -550 ms. Such RPs were used to indicate the minimum onset times for the cerebral activity that precedes a fully endogenous voluntary act. The time of conscious intention to act was obtained from the subject’s recall of the spatial clock position of a revolving spot at the time of his initial awareness of intending or wanting to move (W). W occurred at about -200 ms. Control experiments, in which a skin stimulus was timed (S), helped evaluate each subject’s error in reporting the clock times for awareness of any perceived event.