Is the spatial position of a co-actor coded in shared representations?

Abstract

The Simon task affords two response alternatives that can be distributed amongst a pair of participants to create a joint action task. While no correspondence effect is typically observed when performing a go/no-go (G-NG) task, when completing the exact same task alongside another, the effect arises just as it would if the task were carried out by one person responsible for both responses (Sebanz et al., 2003). These results suggest that knowledge about another person's task is integrated into one's own action plans. We examined whether the joint-correspondence effect is influenced by one's spatial position relative to a partner. We compared performance on variants of the Simon task. In the individual G-NG task, participants carried out one part of the task alone. In the joint G-NG task, the two parts were distributed between paired participants. Participants performed two blocks, with their position relative to their partner changing between blocks. Finally, in the two-choice (TC) task, the participant performed both parts of the task alone. In the individual task, no significant correspondence effect was observed. A strong effect was observed in the TC task. A joint-correspondence effect was seen when participants first performed with a partner. When the participants' position relative to their partner was changed, there was no correspondence effect. We had expected that if the joint-correspondence effect depended on implicitly coding one's position relative to a partner, changing the direction of this spatial relation would lead to participants re-coding their new position and maintain the correspondence effect.

Acknowledgments: Supported by NSERC