Differentiating the reported time of intent and action on the basis of temporal binding behaviors and confidence ratings.

Abstract

The reported time of intent (W) and the reported time of action (M) have been used as indices of consciousness during simple voluntary actions. However, it is unclear whether W is exclusively inferred from M. Past studies have suggested that W is inferred from M by demonstrating that W varies when judged in conjunction with M. The current study offers counterevidence by showing that W is independent of M under some circumstances related to temporal binding. Participants performed a voluntary keypress that elicited a tone (briefly delayed at 5 and 60 ms). Subsequently, they reported W or M and indicated the confidence of their report. Binding strength was measured as the extent to which the W and M reports gravitated toward the time of the tone. Moreover, the binding strength was evaluated in conjunction with time course and knowledge to assess whether the strength increases due to repeated exposure or weakens if informed of the tone delay manipulation, respectively. We observed that the binding strength associated with W increased over time, and being informed of the tone manipulation did not affect W's binding behaviors. In contrast, M's binding behaviors did not change over time but being informed of the tone manipulation may release M from binding. The corresponding confidence ratings associated with W were uniform whereas those associated with M fluctuated over time. Collectively, the results suggest that binding behaviors associated with W and M differ, and that W is not simply derived from M.