Volition and “free will”

Philosophers have debated the “free will” for centuries, yet it is only in recent years that voluntary actions have become an object of investigation for cognitive neuroscience. This review begins by attempting a definition of volition (i.e., the mental state associated specifically with voluntary actions) that could be relevant for cognitive neuroscience. We then review the neuropsychology of volition. Alterations in voluntary behaviour in neurological and psychiatric patients first suggested the possibility that specific cognitive processes of volition have specific bases in the brain. These findings counter traditional dogmas that human volition is somehow ineffable, and instead suggest that voluntary actions depend on specific brain circuitry that is accessible to scientific investigation.The second part of the review focuses on the experimental psychology of volition. A number of studies have combined a systematic manipulation of experimental conditions, and recording of brain processes associated with voluntary action. We argue that this combination is most likely to identify the brain processes specifically associated with volition, and we therefore review these studies systematically. For example, several studies link the Readiness Potential of the EEG to preparatory conscious preplanning of actions. Further, a meta-analysis of neuroimaging studies (PET/ fMRI) reveals a distinctive pattern of activations for choosing one among many possible actions - a key element of volition. The medial frontal cortex appears to make a key contribution to both these biomarkers of volition.