Influence of stimulus--response assignment on the joint-action correspondence effect.

Sebanz et al. (Cognition 88:B11-B21, 2003) have shown that spatial correspondence effects are observed even when the two-choice reaction time task is distributed between two people, such that each person is assigned only one of two possible stimulus-response (S-R) pairings. The effect is similar to when one person is assigned and responds to both S-R pairings. These results have been taken to suggest that two people performing a complementary task co-represent each other's response alternatives. In our experiment, we examined performance when paired participants responded to the same S-R alternative. We reasoned that co-representation would be of little advantage as the task alternatives would be the same for both participants. Correspondence effects were absent when paired participants responded to the same S-R alternative but emerged when they responded to different alternatives.