Power to the will: how exerting physical effort boosts the sense of agency.

The sense of agency refers to the experience of being in control of one's actions and their consequences. The 19th century French philosopher Maine de Biran proposed that the sensation of effort might provide an internal cue for distinguishing self-caused from other changes in the environment. The present study is the first to empirically test the philosophical idea that effort promotes self-agency. We used intentional binding, which refers to the subjective temporal attraction between an action and its sensory consequences, as an implicit measure of the sense of agency. Effort was manipulated independent of the primary task by requiring participants to pull stretch bands of varying resistance levels. We found that intentional binding was enhanced under conditions of increased effort. This suggests not only that the experience of effort directly contributes to the sense of agency, but also that the integration of effort as an agency cue is non-specific to the effort requirement of the action itself.