October 2003
Volume 3, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   October 2003
Accuracy in manually matching the height of a perceptually mislocalized visual target increases with hand-body distance as does manual pointing
Author Affiliations
  • Wenxun Li
    Department of Psychology, Columbia University, New York, NY, USA
Journal of Vision October 2003, Vol.3, 382. doi:10.1167/3.9.382
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      Wenxun Li, Leonard Matin, David Semanek; Accuracy in manually matching the height of a perceptually mislocalized visual target increases with hand-body distance as does manual pointing. Journal of Vision 2003;3(9):382. doi: 10.1167/3.9.382.

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Abstract

Accuracy of open-loop manual pointing to a perceptually mislocalized visual target increases linearly with distance of the hand from the body, approaching complete accuracy at full extension, with errors equal to the perceptual mislocalization for the hand close to the body (Li & Matin, Psychonomic Soc.,1999). To examine this further, we independently varied the distance of a small visual target and the distance of the hand employed for height-matching in the presence of a variably-pitched 1-line inducing stimulus in otherwise total darkness. The height of the visual target was either at 10 cm above, 10 cm below, or 30 cm below the observer's true eye level and at one of three distances from the observer (50, 140, or 300 cm) in the presence of a 50 deg-long pitched-from-vertical line at 25 deg horizontal eccentricity. Manual height matching to the visual target was measured by the Polhemus 3-space search coil with the hand either in the midfrontal plane or at 20 cm or 40 cm in front of the midfrontal plane. The line was set at each of 7 pitches (between −30 deg and +30 deg) at each target/hand combination. The height of the manual height match to the visual target changed linearly with the pitch of the 1-line stimulus in the direction opposite the elevation of the VPEL setting; furthermore, the induced change in elevation increased monotonically with visual target distance (not just a visual angle effect). Although the accuracy of the manual height match increased with hand/body distance, the magnitude of reduction in the height-match error with hand-body distance is roughly constant for the three target distances, indicating that the continuous, gradual decrease of the manual error with increased hand-body distance is due to the distance of the hand from the body, not the distance of the hand to the target.

Li, W., Matin, L., Semanek, D.(2003). Accuracy in manually matching the height of a perceptually mislocalized visual target increases with hand-body distance as does manual pointing [Abstract]. Journal of Vision, 3( 9): 382, 382a, http://journalofvision.org/3/9/382/, doi:10.1167/3.9.382. [CrossRef]
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