Unconscious determinants of free decisions in the human brain

Chun Siong Soon, Marcel Brass, Hans-Jochen Heinze, John-Dylan Haynes
Nature Neuroscience 11, 543 - 545 (2008)

There has been a long controversy as to whether subjectively 'free' decisions are determined by brain activity ahead of time. We found that the outcome of a decision can be encoded in brain activity of prefrontal and parietal cortex up to 10 s before it enters awareness. This delay presumably reflects the operation of a network of high-level control areas that begin to prepare an upcoming decision long before it enters awareness.

Fulltext: http://www.nature.com/neuro/journal/v11/n5/pdf/nn.2112.pdf