Unconscious cerebral initiative and the role of conscious will in voluntary action

Bibliographic Data

ID23322730
AuthorsBenjamin Libet (University of California, San Francisco, corresponding author)
Year1985
Volume8
Issue4
Pages529-539
Publication date1985-12-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueBehavioral and Brain Sciences (JOURNAL)
Journal identifiersISSN: 0140-525X • E-ISSN: 1469-1825
PublisherCambridge University Press (CUP) (PUBLISHER)
DOI10.1017/s0140525x00044903
OpenAlexW2001136156
LanguageEN
Citations received283
References cited83

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. For spontaneous voluntary acts, RP onset preceded the uncorrected Ws by about 350 ms and the Ws corrected for S by about 400 ms. The direction of this difference was consistent and significant throughout, regardless of which of several measures of RP onset or W were used. It was concluded that cerebral initiation of a spontaneous voluntary act begins unconsciously. However, it was found that the final decision to act could still be consciously controlled during the 150 ms or so remaining after the specific conscious intention appears. Subjects can in fact “veto” motor performance during a 100–200-ms period before a prearranged time to act. The role of conscious will would be not to initiate a specific voluntary act but rather to select and control volitional outcome. It is proposed that conscious will can function in a permissive fashion, either to permit or to prevent the motor implementation of the intention to act that arises unconsciously. Alternatively, there may be the need for a conscious activation or triggering, without which the final motor output would not follow the unconscious cerebral initiating and preparatory processes.

Cognitive psychology · Contingent negative variation · Electroencephalography · Political science · Politics · Recall · Stimulus (psychology) · Turnover · Veto · Voluntary action · EEG and Brain-Computer Interfaces · Law · Neural and Behavioral Psychology Studies · Neuroscience · Psychology · Tactile and Sensory Interactions

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