Judy Trevena

Department of Psychology, University of Otago, Dunedin, New Zealand

Cortical Activity and Conscious Decisions

The idea that our actions are determined by our conscious decisions has been challenged by experimental results which suggest that the brain starts preparing for a movement before the person concerned has consciously decided to move (Libet, Gleason, Wright & Pearl, 1983). I will discuss two experiments in which we attempted to replicate Libet et al.'s comparison of participants' movement-related brain activity with the reported times of their decisions to move (and decisions about which hand to move). Although the readiness potential (RP) was usually present before all of the decisions to move (consistent with the findings of Libet et al., 1983) we found that many reported decision-times were before the onset of the lateralized readiness potential (LRP) which measures hand-specific movement preparation. We argue that the cortical processes necessary for the movement to occur may not start until after the conscious decision to move.

Libet, B., Gleason, C. A., Wright, E. W., & Pearl, D. K. (1983). Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential): The unconscious initiation of a freely voluntary act. Brain, 106, 623-642.

This page was last updated on 16 Feb 2001.

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