September 2011
Volume 11, Issue 11
Free
Vision Sciences Society Annual Meeting Abstract  |   September 2011
How well do you know the back of your hand? Reaction time to identify a rotated hand silhouette depends on whether it is interpreted as a palm or back view
Author Affiliations
  • Richard Dyde
    Centre for Vision Research, York University, Toronto
  • Kevin MacKenzie
    Dept. Psychology, Bangor University, Wales
  • Laurence Harris
    Centre for Vision Research, York University, Toronto
Journal of Vision September 2011, Vol.11, 868. doi:10.1167/11.11.868
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      Richard Dyde, Kevin MacKenzie, Laurence Harris; How well do you know the back of your hand? Reaction time to identify a rotated hand silhouette depends on whether it is interpreted as a palm or back view. Journal of Vision 2011;11(11):868. doi: 10.1167/11.11.868.

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

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Abstract

The reaction time (RT) to identify whether an image is of a left or right hand depends on its orientation. Observers mentally rotate the image into a canonical orientation before making their decision. The kinesthetic hypothesis proposes that the RT reflects physiological constraints as if observers actually rotated their hands (Parsons, J Exp Psychol, 1994, 20: 709; Fiorio et al., Brain, 2006, 129:47). To distinguish this hypothesis from a purely visual transform we used silhouettes of hands which could be interpreted as palms or back views – identical images with different physiological constraints. Silhouettes of left and right hands were generated from a single image, mirror imaged and randomly rotated to one of six orientations from 90° (fingers rightwards) through 180° (fingers down) to 270° (fingers leftwards) and viewed through a circular shroud. Fourteen right-hand-dominant observers were tested in two order-counterbalanced conditions. In condition one, observers were instructed that the images were the backs of hands; in condition two they were instructed that they were palms. Their task was to report as quickly and as accurately as possible whether the presented image was a left or right hand using vertically separated key presses. RTs were measured. The canonical positions of the two hands tilted inwards and also depended on view. For hand images presented at 90° and 270° there were significant interactions dependent on the interpreted view: identical stimuli showed different RTs depending on whether observers were instructed that the image was a right or left hand. For intermediate orientations (130° through 230°) a more complex pattern emerged with effects of view (palm/back) and laterality (left/right). Our pattern of results broadly supports the kinesthetic hypothesis. However, RT is also influenced by image orientation interacting with hand laterality and how the image is interpreted.

Supported by the Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada. KM held an OGS scholarship. 
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