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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. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Peripersonal space (PPS) is a multisensory representation of the space near body parts facilitating interactions with the close environment. Studies on non-human and human primates converge in showing that PPS is a body-part-centred representation that guides actions. Because of these characteristics, growing confusion conflates peripersonal and arm-reaching space (ARS), that is the space one’s arm can reach. Despite neuroanatomical evidence favors their distinction, no study has contrasted directly their respective extent and behavioral features. Here, in five experiments (N=140) we found that PPS differs from ARS, as evidenced both by participants’ spatial and temporal performance and its modeling. We mapped PPS and ARS using both their respective gold standard tasks and a novel multisensory facilitation paradigm. Results show that 1) PPS is smaller than ARS; 2) multivariate analyses of spatial patterns of multisensory facilitation predict participants’ hand locations within ARS; 3) the multisensory facilitation map shifts isomorphically following hand positions, revealing hand-centred coding of PPS, therefore pointing to a functional similarity to the receptive fields of monkeys’ multisensory neurons. A control experiment further corroborated these results and additionally ruled out the orienting of attention as driving mechanism for the increased multisensory facilitation near the hand. In sharp contrast, ARS mapping results in a larger spatial extent, with undistinguishable patterns across hand positions, cross-validating the conclusion that PPS and ARS are distinct spatial representations. These findings urge for a refinement of theoretical models of PPS, which is relevant to constructs as diverse as self-representation, social interpersonal distance, and motor control.

Previous research using immersive virtual reality (VR) has shown that after a short period of embodiment by White people in a Black virtual body, their implicit racial bias against Black people diminishes. Here we tested the effects of some socio-cognitive variables that could contribute to enhancing or reducing the implicit racial bias. The first aim of the study was to assess the beneficial effects of cooperation within a VR scenario, the second aim was to provide preliminary testing of the hypothesis that empathy and political attitudes could contribute to implicit bias about race, while the third aim was to explore the relationship between political attitudes and empathy. We had (Caucasian) participants embodied in a Black virtual body and engaged either in a cooperative (Coop group) or in a non-cooperative (Neutral group) activity with a confederate experimenter embodying another Black avatar. Before and after VR, we measured participants’ implicit racial bias by means of Implicit Association Test (IAT) and their perceived closeness toward the confederate experimenter. Before VR we also assessed participants’ political attitudes and empathy traits. Results revealed that, as compared to the Neutral group, the Coop group showed lower IAT scores after the social interaction. Interestingly, in the Neutral but not the Coop group the perceived closeness toward the confederate experimenter was associated with the initial racial bias: the more the participants reduced their distance, the more they reduced their IAT score. Moreover, reported traits of empathy and political attitudes significantly explained the variance observed in the initial implicit bias, with perspective-taking, empathic concern, and personal distress being significant predictors of the IAT scores. Finally, there was a relationship between political attitudes and empathy: the more participants considered themselves as left-wing voters, the higher their perspective-taking and empathic concern scores. We discuss these findings within the neuroscientific and social cognition field and encourage scholars from different domains to further explore whether and under which conditions a given manipulation for reducing racial bias could be efficiently transposed in VR.

The space surrounding people is often termed Interpersonal (IPS) in social psychology and Peripersonal (PPS) in neuroscience. In the current debate about their origin, the prevalent opinion is they share common functional characteristics. Bucking the trend, here we report a dissociation between PPS, operationalized as reachable space, and IPS, operationalized as comfort space. To probe their plasticity we introduced a novel type of cooperative long-tool-use that would modify both spaces. Results showed the estimated IPS referred to another individual was reduced, as expected following a positive social interaction. In sharp contrast, the estimated PPS toward the very same cooperative person was actually extended after use of the same long-tool. Control short-tool-use selectively reduced IPS, but not PPS, when performed in the same cooperative set or had no effect on either space estimation, when performed in a neutral set where the other person is not interacting cooperatively, but simply observing. The use of tools to perform actions in social settings allows us to report the first strong evidence that PPS and IPS underlie dissociable plastic representations: the former representation is sensitive to long-tool-dependent plasticity, whereas the latter representation, independently of use of a short or long tool, is sensitive to cooperation-dependent plasticity.

We describe a right-handed patient (M.B.), who developed left hemianopsia and a severe reading impairment after right occipital-parietal hemorrhage. The pattern of his reading deficit was very similar to that of pure alexia (alexia-without-agraphia): extremely slow reading times with frequent grapheme substitutions and omissions. A test of letter reading while controlling for saccadic eye movements and hemifield of presentation ruled out hemianoptic alexia. Although there have already been reports of reading impairments in right handers following right- hemispheric lesions, ours is, to the best of our knowledge, the first where visual field loss can be definitely excluded as the main cause. Based on a standard neuropsychological assessment and on additional behavioral tests, we argue that M.B.'s difficulties are unlikely to be due to right-hemisphere dominance for language. After considering several candidate explanations, we suggest that M.B.'s symptoms may be related to an impairment in attentional processes related to reading.

Converging evidence suggests close relationships between the action and social space representations. The concepts of peripersonal space, as defined by cognitive neuroscience, and interpersonal space, as defined by social psychology, refer to approximately the same spatial area surrounding our bodies. The aim of this study was thus to assess experimentally whether the peripersonal (PPS) and interpersonal space (IPS) represent a similar psychological entity. Were this true, they should share some functional features. Here we tested tool-use dependent plasticity, known to modulate PPS, but still unexplored in the IPS. Results from two experiments converge in showing that tool-use remapped the action-related PPS, measured by a Reaching-distance toward a confederate, but did not affect the social-related IPS, measured by a Comfort-distance task. These findings indicate that PPS and IPS rely on dissociable plastic mechanisms and suggest that, at least in the present experimental conditions, there is no full functional overlap between these two spatial representations.

Rightward prismatic adaptation (RPA) can reduce neglect symptoms in patients whereas adaptation to leftward deviating prisms (LPA) can induce neglect-like behavior in healthy subjects. One influential anatomo-functional model of prismatic adaptation (PA) postulates that it inhibits activity of the posterior parietal cortex (PPC) contralateral to the prismatic deviation. By hypo-activating the PPC and thus eventually acting on interhemispheric balance, both LPA and RPA could possibly affect visuospatial perception in healthy subjects, however, such behavioral modulation has seldom been reported after RPA. In the light of recent evidence showing that LPA-induced visuospatial shift need time to develop we hypothesized that RPA might induce significant changes in visuospatial cognition on a longer time scale. We thus assessed the Landmark task, as well as sensorimotor aftereffects, several times over 8 h after a single session of either LPA or RPA. In agreement with previous reports, sensorimotor effects were symmetrical and long-lasting, with both LPA and RPA inducing shifts of comparable amplitudes in the direction opposite to the deviation that lasted up to 8 h. Visuospatial cognition assessed by Landmark performance, was also significantly modulated for up to 8 h, but only after LPA. Interestingly, the timing and direction of this modulation differed according to participants' baseline bias. An initial leftward bias led to a rapid, but short-lasting rightward shift, whereas an initial rightward bias led to a slower-developing and longer-lasting leftward shift. These findings shed new light on a so-far relatively overlooked feature of spatial cognition that may interact with the effect of PA: the state of the visuospatial system prior to PA should be taken into account when attempting to understand and modulate visuospatial cognition in healthy and brain-damaged populations. This highlights the need for refining current models of PA's mechanisms of action.