Representing relations between individual contributions: when does joint action planning facilitate task performance?

Understanding how individuals plan, predict and adapt their actions is central to understanding the high degree of coordination involved in joint action. While previous research has examined the role of joint action plans in linking individual action representations in a two-person joint action plan, the specific conditions and representations associated with these plans are less well understood. In this study, we investigated when and how joint action plans that specify the relations between individual contributions facilitate performance in a joint task. We hypothesized that joint action plans serve to organize individual contributions to a joint action by specifying the relations between them. Pairs of participants performed a joint computer task that required flipping blocks to produce a joint pattern. We manipulated the availability and information provided by two types of pre-cues: joint cues specified the relation between individual contributions and individual cues specified each participant’s individual part. The results of three experiments showed that information regarding the relation between individual contributions helped co-actors integrate representations of their individual contributions. This is evidenced by faster response times when a joint cue was presented together with a cue specifying the partner’s action. Moreover, joint cues could be used to compensate for the lack of information about individual contributions, as evidenced by faster response times when a joint cue was presented in trials without information about individual contributions. We conclude that joint action plans that specify the relations between individual contributions serve to organize representations of individual contributions and thereby help co-actors infer their own underspecified contribution to a joint action.