Interpersonal motor interactions remap visuotactile integration

Expansions of the Peri-Personal Space during individual action execution have been indexed by measuring cross-modal interferent effects of distant visual cues over the ability to detect tactile stimuli that are spatially congruent or incongruent with the end-location of one’s action. Here we studied whether these effects are modulated by the presence of a partner with which participants need to coordinate in a joint-grasping task as a function of the nature of the interaction requiring or not to predict the movements of a partner. Eighteen participants were asked to grasp an object synchronously with a facing virtual partner by performing OPPOSITE/SAME movements to those of the partner (FREE condition) and to detect a tactile stimulus on their finger while spatially IN/CONGRUENT visual cues with the participants’ end-location appeared on the to-be-grasped object. As a control condition (GUIDED), participants were instructed to synchronize with the partner and to ignore the target position of the partner action. The classical interferent effect of spatially incongruent visual cues over tactile detection was abolished selectively when participants needed to predict the movement of the partner (FREE) during OPPOSITE interactions showing that visuo-tactile integration is remapped by the rules of interpersonal interactions.