Brain signals do not demonstrate unconscious decision making: An interpretation based on graded conscious awareness

• Decision-related changes in brain activity sometimes precede conscious decisions.
• It is therefore claimed that decisions are made unconsciously by the brain.
• This claim assumes that conscious states vary in an all-or-none manner.
• We review evidence that–on the contrary–conscious states vary gradually.
• Thus, unconscious decision-making by the brain has not actually been demonstrated.

Neuroscientific studies have shown that brain activity correlated with a decision to move can be observed before a person reports being consciously aware of having made that decision (e.g., Libet, Gleason, Wright, & Pearl, 1983; Soon, Brass, Heinze, & Haynes, 2008). Given that a later event (i.e., conscious awareness) cannot cause an earlier one (i.e., decision-related brain activity), such results have been interpreted as evidence that decisions are made unconsciously (e.g., Libet, 1985). We argue that this interpretation depends upon an all-or-none view of consciousness, and we offer an alternative interpretation of the early decision-related brain activity based on models in which conscious awareness of the decision to move develops gradually up to the level of a reporting criterion. Under this interpretation, the early brain activity reflects sub-criterion levels of awareness rather than complete absence of awareness and thus does not suggest that decisions are made unconsciously.