ERP correlates of processing the auditory consequences of own versus observed actions

Research has so far focused on neural mechanisms that allow us to predict the sensory consequences of our own actions, thus also contributing to ascribing them to ourselves as agents. Less attention has been devoted to processing the sensory consequences of observed actions ascribed to another human agent. Focusing on audition, there is consistent evidence of a reduction of the auditory N1 ERP for self- versus externally generated sounds, while ERP correlates of processing sensory consequences of observed actions are mainly unexplored. In a between-groups ERP study, we compared sounds generated by self-performed (self group) or observed (observation group) button presses with externally generated sounds, which were presented either intermixed with action-generated sounds or in a separate condition. Results revealed an overall reduction of the N1 amplitude for processing action- versus externally generated sounds in both the intermixed and the separate condition, with no difference between the groups. Further analyses, however, suggested that an N1 attenuation effect relative to the intermixed condition at frontal electrode sites might exist only for the self but not for the observation group. For both groups, we found a reduction of the P2 amplitude for processing action- versus all externally generated sounds. We discuss whether the N1 and the P2 reduction can be interpreted in terms of predictive mechanisms for both action execution and observation, and to what extent these components might reflect also the feeling of (self) agency and the judgment of agency (i.e., ascribing agency either to the self or to others).