Benjamin Libet's Work on the Neuroscience of Free Will

Awareness of action: Inference and prediction

“…This method has proved to be one of the few viable experimental approaches to conscious experience of voluntary action. In spite of this, the timing method has attracted considerable criticism (see Banks & Pockett, 2006, for a review). Factors such as attention and 'prior entry' (Titchener, 1908) mean that any single time estimate needs to be treated with caution.…”

Subjective reports of stimulus, response, and decision times in speeded tasks: How accurate are decision time reports?

“…They examined the neural activity before and after the moments at which people indicated they had made their decisions, and the results suggested that the brain had already started getting ready to act before the time at which people reported deciding to do so-a finding that has also been replicated in other laboratories (e.g., Haggard & Eimer, 1999;Trevena & Miller, 2002). As has been discussed extensively since the original result (e.g., Banks & Pockett, 2007;Gomes, 1999;Haggard, 2008;Mele, 2006;Roediger, Goode, & Zaromb, 2008;Shibasaki & Hallett, 2006;Spence, 1996;Wegner, 2003), the findings of Libet et al support the idea that people's decisions to move are made unconsciously by the brain before people are aware of making them. This implies that such actions are determined by unconscious brain processes and perhaps even that our subjective impression of having the free will to choose our actions is just an illusion (e.g., Kawohl & Habermeyer, 2007;Libet, 1992).…”

The neural basis of event-time introspection

“…The finding that a brain potential related to action preparation starts several hundred milliseconds before the participants introspectively decide to move has had major impact on discussions about the significance of consciousness and free will (Banks & Pockett, 2007; Haggard, 2008). Yet, even though the results were reproduced and extended by independent groups (Haggard & Eimer, 1999; Trevena & Miller, 2002), as well as with fMRI measurements (Soon, Brass, Heinze, & Haynes, 2008), and with single neuron recordings (Fried, Mukamel, & Kreiman, 2011), their implications remain a matter of debate, in particular because it is unknown how we introspect and whether introspective reports are accurate (Klein, 2002; Banks & Pockett, 2007; Danquah, Farrell, & O’Boyle, 2008). Participants in these studies were typically asked to watch a rapidly rotating clock hand, to memorize its position each time they “felt the urge to move”, and to report it after the actual physical movement, and this has been commonly referred to as the Libet-paradigm .…”