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開催日 2014/9/13
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Changes in bodily self-consciousness and body representations by manipulating virtual body part

  • P3-271
  • 渋谷 賢 / Satoshi Shibuya:1 大木 紫 / Yukari Ohki:1 
  • 1:杏林大学・医・統合生理 / Dept of Physiol, Kyorin Univ, Sch of Med, Japan 

We examined bodily self-consciousness (senses of agency and ownership) and body representations (body image and body schema), when illusion was induced by manipulating a virtual hand. Normal subjects (n=16) placed the right forearm on a 2D manipulandum with a low-friction. The real hand was not visible, but an image of the life-size right hand was displayed 12 cm in front of the real one. For the illusion, subjects were required to move the image cyclically for four minutes, by moving the real hand. A 2 x 2 factorial design was applied to differentially induce the senses of agency and ownership by the intervention. One factor was movement type (active or passive), in which the real hand was moved by the subject or experimenter. The other was congruency (congruent or incongruent), where arrangement of the virtual hand was either anatomically congruent to the real or rotated at 180 degrees. Body representations were estimated by proprioceptive drifts in three tests, before and after the intervention: bilateral arm position matching (BM), visual position judgment using a ruler (VJ), and target-reaching movement (TR). After the intervention, senses of agency and ownership, evaluated by a Likert rating-scale questionnaire, showed evidence for a double dissociation between conditions, as reported in previous studies. Body representations were also affected by the intervention, but to slightly different extents in three parameters. Drifts in BM were observed only in the congruent conditions, regardless of the movement type. On the other hand, VJ and TR were influenced by both factors: drifts were greater in the congruent than the incongruent, and in the active than the passive conditions. Between the three, VJ was significantly correlated with TR (r=0.4, p<0.01) and BM (r=0.3, p<0.05), but a correlation was not shown between TR and BM (r=0.05). Multiple regression analyses revealed that the sense of ownership, but not sense of agency, could be explained by the three parameters (r=0.47, p<0.01), for which BM (β=0.39, p<0.01) contributed mainly. These results suggest that manipulating virtual body part would alter body representations in different ways, and that some parts of these changes are linked to the sense of ownership in bodily self-consciousness.

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