Social scaling of extrapersonal space: Target objects are judged as closer when the reference frame is a human agent with available movement potentialities

• Published in: Cognition 2015-01, Vol.134, p.50-56
• Main Authors: Fini, C., Brass, M., Committeri, G.
• Format: Article
• Language: English
• Subjects: Adult; Allocentric; Body; Cognition; Distance Perception - physiology; Ecological validity; Female; Humans; Male; Motor potentialities; Movement; Perception; Personal Space; Reference frames; Social Perception; Space; Virtual reality; Young Adult
• ISSN: 0010-0277; 1873-7838
• DOI: 10.1016/j.cognition.2014.08.014

•Distance categorization in extrapersonal space is affected by the RF’s nature.•The distance between a RF and an object is reduced if the RF is a human agent.•Movement potentialities of a human RF contribute to the extension of “Near” space. Space perception depends on our motion potentialities and our intended actions are affected by space perception. Research on peripersonal space (the space in reaching distance) shows that we perceive an object as being closer when we (Witt, Proffitt, & Epstein, 2005; Witt & Proffitt, 2008) or another actor (Costantini, Ambrosini, Sinigaglia, & Gallese, 2011; Bloesch, Davoli, Roth, Brockmole, & Abrams, 2012) can interact with it. Similarly, an object only triggers specific movements when it is placed in our peripersonal space (Costantini, Ambrosini, Tieri, Sinigaglia, & Committeri, 2010) or in the other’s peripersonal space (Costantini, Committeri, & Sinigaglia, 2011; Cardellicchio, Sinigaglia, & Costantini, 2013). Moreover, also the extrapersonal space (the space outside reaching distance) seems to be perceived in relation to our movement capabilities: the more effort it takes to cover a distance, the greater we perceive the distance to be (Proffitt, Stefanucci, Banton, & Epstein, 2003; Sugovic & Witt, 2013). However, not much is known about the influence of the other’s movement potentialities on our extrapersonal space perception. Three experiments were carried out investigating the categorization of distance in extrapersonal space using human or non-human allocentric reference frames (RF). Subjects were asked to judge the distance (“Near” or “Far”) of a target object (a beach umbrella) placed at progressively increasing or decreasing distances until a change from near to far or vice versa was reported. In the first experiment we found a significant “Near space extension” when the allocentric RF was a human virtual agent instead of a static, inanimate object. In the second experiment we tested whether the “Near space extension” depended on the anatomical structure of the RF or its movement potentialities by adding a wooden dummy. The “Near space extension” was only observed for the human agent but not for the dummy. Finally, to rule out the possibility that the effect was simply due to a line-of-sight mechanism (visual perspective taking) we compared the human agent free to move with the same agent tied to a pole with a rope, thus reducing movement potentialities while maintaining equal visual accessibility. The “Near