Me, you, and our object: Peripersonal space recruitment during executed and observed actions depends on object ownership

Peripersonal space (PPS) is a spatial representation that codes objects close to one's own and to someone else's body in a multisensory-motor frame of reference to support appropriate motor behavior. Recent theories framed PPS beyond its original sensorimotor aspects and proposed to relate it to social aspects of the self. Here, we manipulated the ownership status of an object ("whose object this is") to test the sensitivity of PPS to such a pervasive aspect of society. To this aim, we assessed PPS through a well-established visuo-tactile task within a novel situation where we had dyads of participants either grasping or observing to grasp an object, whose ownership was experimentally assigned to either participant (individual ownership), or to both participants (shared ownership). When ownership was assigned exclusively ("this belongs to you/the other," Experiment 1), the PPS recruitment emerged when grasping one's own object (I grasp my object), as well as when observing others grasping their own object (you grasp your object). Instead, no PPS effect was found when grasping (and observing to grasp) an object that was not one's own (I grasp yours, you grasp mine). When ownership was equally assigned ("this belongs to both of you," Experiment 2), a similar PPS recruitment emerged and, again, both when the action toward the shared object was executed and merely observed. These findings reveal that ownership is critical in shaping relatively low-level aspects of body-object interactions during everyday simple actions, highlighting the deep mark of ownership over social behavior.