Action fluency and conscious intention: being aware of what we are about to do.

Voluntary actions are often accompanied by a clear, preceding conscious experience of intention. However, the nature of this experience, and the neural mechanisms underlying it, have proved difficult to study scientifically. Many previous studies instructed participants to make simple manual actions, and then report their preceding intention only retrospectively. We combined a typing-based verbal fluency paradigm with pseudorandom probes of conscious experience to address these issues, and used electroencephalography (EEG) to explore neural correlates of prospective intention. Across one behavioral and one EEG experiment, involving 51 participants, we found conscious intention emerged over 1 s before estimated action onset. Further, we found an EEG readiness-potential-like activity that was stronger prior to probes that participants reported as interrupting a conscious intention, compared to other probes. In addition, probes that interrupted conscious intention were found to occur after lateralization of the readiness-potential-like activity to the hemisphere contralateral to the hand that participants reported would type the first letter. Our results provide novel evidence for a prospective experience of conscious intention associated with neural processes that precede voluntary actions. Significance Statement Many models of voluntary action assume that an experience of conscious intention precedes movement onset, but the mechanisms underlying this experience are highly controversial. By randomly probing experiences of intention during an action generation task involving typing-based verbal fluency, we developed a new method for estimating time of conscious intention, and its neural mechanisms. The method estimates that experiences of prospective intention occur over 1 s before action. Concurrent EEG recordings suggested that the EEG signals classically used as precursor indices of voluntary action are also associated with the experience of prospective intention.