Monitoring of Movement execution and Goal achievement influences the Sense of Agency

The Sense of Agency (SoA) - the feeling of controlling one’s body to influence external outcomes - is reduced by unpredicted events. We present a novel paradigm which investigates the combined contribution to SoA of movement execution and goal achievement. Thirty volunteers performed goal-directed actions consisting in pressing one of two buttons following a color cue, by lowering or raising their index finger. Participants observed a virtual hand from a first-person perspective acting simultaneously (0 msec delay) or after various delays (75, 150, 225, 300 msec) and Movement (same/opposite) and Goal (success/failure to press the signaled color) were manipulated. We collected judgments of correspondence - an explicit index of SoA that overcomes the tendency to over-attribute actions to oneself - by asking participants if the observed action was synchronous or not with their own action. We calculated the proportion of “synchronous” answers for each participant and each condition and entered mean values in a 2x2x5 ANOVA with Movement, Goal and Delay as within-subjects factors. Participants perceived opposite movements as less synchronous, irrespective of the duration of the delay (main effect of Movement). Further, observing a failure to achieve the goal was associated to lower perceived synchrony only when the observed action was simultaneous (0 msec) or presented after 75 msec (Goal x Delay interaction). These results suggest that SoA is modulated by monitoring both movement execution and goal achievement. Interestingly, goal manipulation was effective only within a short temporal window, suggesting that SoA is more sensitive to movement execution.