title: Roles of the upper and lower bodies in direction discrimination of point-light walkers.
abstract: We can easily recognize human movements from very limited visual information (biological motion perception). The present study investigated how upper and lower body areas contribute to direction discrimination of a point-light (PL) walker. Observers judged the direction that the PL walker was facing. The walker performed either normal walking or hakobi, a walking style used in traditional Japanese performing arts, in which the amount of the local motion of extremities is much smaller than that in normal walking. Either the upper, lower, or full body of the PL walker was presented. Discrimination performance was found to be better for the lower body than for the upper body. We also found that discrimination performance for the lower body was affected by walking style and/or the amount of local motion signals. Additional eye movement analyses indicated that the observers initially inspected the region corresponding to the upper body, and then the gaze shifted toward the lower body. This held true even when the upper body was absent. We conjectured that the upper body subserved to localize the PL walker and the lower body to discriminate walking direction. We concluded that the upper and lower bodies play different roles in direction discrimination of a PL walker.
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan. ktakahashi@fennel.rcast.u-tokyo.ac.jp
authors.forename: Kohske
authors.initials: K
authors.lastname: Takahashi
authors.forename: Haruaki
authors.initials: H
authors.lastname: Fukuda
authors.forename: Hanako
authors.initials: H
authors.lastname: Ikeda
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Doi
authors.forename: Katsumi
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ueda
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Shinohara
mesh_terms: D004192:Discrimination, Psychological / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D016138:Walking / Q000502:physiology*