title: Representing human hands haptically or visually from first-person versus third-person perspectives.
abstract: Humans can recognise human body parts haptically as well as visually. We employed a mental-rotation task to determine whether participants could adopt a third-person perspective when judging the laterality of life-like human hands. Female participants adopted either a first-person or a third-person perspective using vision (experiment 1) or haptics (experiment 2), with hands presented at various orientations within a horizontal plane. In the first-person perspective task, most participants responded more slowly as hand orientation increasingly deviated from the participant's upright orientation, regardless of modality. In the visual third-person perspective task, most participants responded more slowly as hand orientation increasingly deviated from the experimenter's upright orientation; in contrast, less than half of the participants produced this same inverted U-shaped response-time function haptically. In experiment 3, participants were explicitly instructed to adopt a third-person perspective haptically by mentally rotating the rubber hand to the experimenter's upright orientation. Most participants produced an inverted U-shaped function. Collectively, these results suggest that humans can accurately assume a third-person perspective when hands are explored haptically or visually. With less explicit instructions, however, the canonical orientation for hand representation may be more strongly influenced haptically than visually by body-based heuristics, and less easily modified by perspective instructions.
authors.affiliation: Division of Cerebral Integration, National Institute for Physiological Sciences, Okazaki, 444-8585, Japan. kitada@nips.ac.jp
authors.forename: Ryo
authors.initials: R
authors.lastname: Kitada
authors.forename: H Chris
authors.initials: HC
authors.lastname: Dijkerman
authors.forename: Grace
authors.initials: G
authors.lastname: Soo
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Lederman
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D005260:Female; D005556:Form Perception / Q000502:physiology*; D007839:Functional Laterality; D006225:Hand; D006801:Humans; D009949:Orientation; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011930:Reaction Time; D021641:Recognition, Psychology; D055815:Young Adult