June 2007
Volume 7, Issue 9
Vision Sciences Society Annual Meeting Abstract  |   June 2007
Sex classification of point-light walkers: Viewpoint, structure, kinematics
Author Affiliations
  • Anna Halevina
    Department of Psychology, Queen's University, Kingston, Canada
  • Nikolaus F. Troje
    Department of Psychology, Queen's University, Kingston, Canada
Journal of Vision June 2007, Vol.7, 483. doi:10.1167/7.9.483
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      Anna Halevina, Nikolaus F. Troje; Sex classification of point-light walkers: Viewpoint, structure, kinematics. Journal of Vision 2007;7(9):483. doi: 10.1167/7.9.483.

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      © ARVO (1962-2015); The Authors (2016-present)

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Biological motion point-light walkers convey information about the sex of a walker. As has been shown earlier, retrieving this information depends on the viewpoint: Frontal views are easier to classify than profile views. However, what happens if a walker is shown from a varying viewpoint as is the case when we see a walker walking on a circle? Multiple viewpoints should facilitate activation of a three-dimensional representation which might help classification. On the other hand, the additional rotation might mask intrinsic (that is, relative) motion diagnostic for the sex of the walker and therefore hinder classification. In the current study, observers had to indicate perceived sex of point-light displays of individual walkers shown either in frontal view (0 deg), half profile view (30 deg), profile view (90 deg), or in a condition in which the viewpoint rotated from −50 to 50 deg over the display time of 2 sec. In addition, we manipulated the information provided. Walkers contained either only structural information, only kinematic information, or all information. The results replicated earlier findings showing that performance at frontal and half profile view is much better than at profile view and that kinematic information is required for sex classification whereas structural information has very little diagnostic value. In addition, we could show that rotating views of a walker are clearly resulting in worse classification than frontal or half-profile views, but were classified much better than profile view walkers. We conclude that three-dimensional representations do not facilitate sex classification from biological motion. Diagnostic information about sex is primarily contained in the kinematics within the fronto-parallel plane and the motion due to rotation of the walker aggravates retrieval of this information.

Halevina, A. Troje, N. F. (2007). Sex classification of point-light walkers: Viewpoint, structure, kinematics [Abstract]. Journal of Vision, 7(9):483, 483a, http://journalofvision.org/7/9/483/, doi:10.1167/7.9.483.

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