ERP correlates of agency processing in joint action.

In the Ouija board phenomenon, the lack of agency experienced by the players leads them to attribute the movement of the planchette to spirits. The aim of this study was to investigate the neural and cognitive mechanisms involved in generating the sense of agency in such a joint action context. Two players (a participant and a confederate) jointly moved a Ouija board-style planchette containing a wireless mouse. This, in turn, moved a digital board on the screen. Participants reported a greater sense of agency in the condition where they had complete control of the planchette (the 'self' condition), and least agency when they passively held the planchette while it was moved by the confederate ('other' condition), with the two 'joint' action conditions in between. While the N1 peak did not differ between conditions, the early part of the N1 differentiated between the joint action conditions, and the solo action conditions. In contrast, the Tb and P2 components differed between the 'other' condition and the 'self' and 'joint' conditions. These findings are discussed with reference to motor-prediction and attentional mechanisms.