My partner is also on my mind: social context modulates the N1 response.

When individuals share a task with a partner, one's own actions and one's partner's actions have to be precisely tuned to one another. With behavioral means, it has been numerously shown that splitting a simple reaction time task between two participants produces similar interference patterns to those occurring when controlling the whole task on one's own. Less is known about the neuronal correlates when sharing a task with a partner. The processes of agent identification ("my turn" vs. "my partner's turn") were the focus of this study. In an EEG study, pairs of participants responded to different action-associated stimuli in a Go/NoGo paradigm. The same task was performed together with a partner (joint Go/NoGo condition) and when a partner was not present (single Go/NoGo condition). This study showed a top-down influence of social setting on early visual processing as indexed by the Go-N1 and NoGo-N1 response. This effect was only present in the joint Go/NoGo condition. It was particularly present in those trials where the partner did not have to act. Taken together, these results yield evidence for an early top-down influence of social setting on early processes of stimulus identification and differentiation.