The Peripersonal Space: A Space to INTER-ACT Action- and Social-related Modulations of the Space around Us

The zone surrounding our body is of vital importance. In neuroscience this space is captured by the concept of peripersonal space (PPS), a plastic representation integrating tactile and visual stimuli presented on/close to the body. PPS is thought to contribute to the efficient guidance of actions, yet, a clear demonstration of this function is critically lacking. In the first study we provided strong support to this hypothesis by revealing that visual and tactile stimuli interact already during action planning. Such a PPS remapping that precedes motor execution is ideally suited to guiding actions. Recently, it has been suggested a possible PPS involvement in social interactions. In social psychology, interpersonal space (IPS) is the area individuals maintain around themselves into which others cannot intrude without arousing discomfort. Because of some similarities, some authors raised the question of whether PPS and IPS share some functional features. In the second and third study we tested this hypothesis by taking advantage of PPS remapping induced by tool-use. First, we showed that “standard” tool-use ‘extends’ PPS, as measured by reaching-distance toward a peer, but does not affect IPS, as measured by the comfort-distance toward the same peer. Then, we demonstrated that a novel “social” tool-use ‘extends’ PPS and ‘reduces’ IPS. These findings clearly disconfirm the hypothesis of functional overlap between the two spaces. The last study examines the sensitivity of PPS to a fundamental social dimension: ownership. The results indicate that ownership of an object is critical for the PPS remapping to emerge. Visual stimuli strongly affected touch perception during action only when the object belonged to the participant. A similar remapping emerged when simply observing a peer acting on her own object. Taken together, these findings critically inform current models about space perception and about its function in our sensorimotor and social inter-actions.