Abstract
Libet's study of the readiness potential (RP; Libet et al., 1983) - an event-related potential (ERP) that precedes endogenously-willed actions - has called into question the ability of our conscious will to cause behavior. Since the RP begins well before subjects report willing a movement, some have concluded that conscious volition is illusory - a report to our conscious mind of decisions that our unconscious brain has already made (see Libet, 1993). An associated ERP known as the lateralized readiness potential (LRP) also precedes reports of conscious decisions to act and provides further ammunition for this position. In this study we performed two experiments. First, we replicated Libet's method and additionally compared the reported time of conscious willing of movements to corresponding onsets of the RP and LRP. We found no covariation between this reported time and either the RP or LRP onset, suggesting that the RP and LRP may underlie processes independent from volition. Second, we recorded RP-like ERPs in subjects as they readied an exogenously-cued movement, suggesting that the RP may reflect processes of anticipation or preparation rather than volition. This conclusion is supported by a previous report (Matsuhashi & Hallett 2008) that thoughts of movement begin well before reports of conscious will, and if true would leave open the possibility that conscious volition can cause behavior.