Joint response-effect compatibility

When performing jointly on a task, human agents are assumed to represent their coactor’s share of this task, and research in various joint action paradigms has focused on representing the coactor’s stimulus–response assignments. Here we show that the response–effect (R–E) contingencies exploited by a coactor also affect performance, and thus might be represented as if they were used by oneself. Participants performed an R–E compatibility task, with keypresses producing spatially compatible or incompatible action effects. We did not observe any R–E compatibility effects when the task was performed in isolation (individual go–no-go). By contrast, small but reliable R–E compatibility effects emerged when the same task was performed in a joint setting. These results indicate that the knowledge of a coactor’s R–E contingencies can influence whether self-produced action effects are used for one’s own motor control