Ownership Status Influences the Degree of Joint Facilitatory Behavior.

When engaging in joint activities, humans tend to sacrifice some of their own sensorimotor comfort and efficiency to facilitate a partner's performance. In the two experiments reported here, we investigated whether ownership-a socioculturally based nonphysical feature ascribed to objects-influenced facilitatory motor behavior in joint action. Participants passed mugs that differed in ownership status across a table to a partner. We found that participants oriented handles less toward their partners when passing their own mugs than when passing mugs owned by their partners (Experiment 1) and mugs owned by the experimenter (Experiment 2). These findings indicate that individuals plan and execute actions that assist their partners but do so to a smaller degree if it is the individuals' own property that the partners intend to manipulate. We discuss these findings in terms of underlying variables associated with ownership and conclude that a self-other distinction can be found in the human sensorimotor system.