Poster C97, Sunday, March 25, 1:00-3:00 pm, Exhibit Hall C
Changes in perceived peripersonal space following the rubber hand illusion
Miranda Smit1, Veerle Kurstjens1, Chris Dijkerman1, Ineke van der Ham2, Maarten van der Smagt1; 1Utrecht University, Department of Experimental Psychology, Helmholtz Institute, Utrecht, The Netherlands, 2Department of Health, Medical, and Neuropsychology, Leiden University, the Netherlands
The peripersonal space (PPS) is the region immediately surrounding the body, and is essential for bodily protection and goal directed action. Since the PPS is anchored to one’s own body, we investigated whether PPS could be modulated by changes in body ownership. The rubber hand illusion (RHI) is a way to manipulate body ownership and is induced by placing a fake hand next to one’s own hidden hand and stroking them in synchrony. We hypothesized that after the RHI the perceived body midline shifted would shift to the right, suggesting a relocation in PPS from the real hand to the fake hand. Thirty-eight participants performed a landmark test before and after the RHI. Half of the participants experienced synchronous stroking, the other half experienced asynchronous stroking. In the landmark task, participants had to determine whether a landmark was left or right from the center of the screen. Each participant’s data were fitted with a cumulative normal distribution function to generate estimates of the point of subjective equality (PSE). Results showed a shift in PSE, but only after synchronous stroking, which indicates that the perceived midline of the bodily space shifted to the right. Since the PPS is anchored to the body, these results suggest that the relevant action space becomes linked to the fake hand. Critically, subjective ownership did not correlate with this shift. This suggests that multisensory (e.g., visual, tactile, proprioceptive) integration of bodily information drives this shift in PPS and not experience of ownership per se.
Topic Area: PERCEPTION & ACTION: Multisensory