Abstract
The onset of the readiness potential (RP)—a key neural correlate of upcoming action—was repeatedly found to precede subjects’ reports of having decided. This was famously taken as evidence against a causal role for consciousness in human decisions making and thus as an attack on free-will. Yet those studies focused on purposeless, unreasoned, arbitrary decisions, bereft of consequences. So, it remains unknown to what degree these neural precursors of action generalize to deliberate decisions, which are arguably more interesting, ecological, and relevant to real life. We therefore directly compared the neural correlates of deliberate and arbitrary decisions during a $1000-donation task to non-profit organizations. While we found the expected RPs for arbitrary decisions, they were strikingly absent for deliberate ones. Our results are congruent with the RP representing the accumulation of noisy, random fluctuations, which drive arbitrary—but not deliberate—decisions. In that they challenge the generalizability of studies that argue for no causal role for consciousness in decision making from arbitrary to deliberate decisions.