June 2006
Volume 6, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2006
The effect of contrast variations on the perception of Glass patterns
Author Affiliations
  • Charles C.-F. Or
    Centre for Vision Research, York University, Toronto, Ontario, Canada.
  • Sieu K. Khuu
    Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
  • Anthony Hayes
    Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Journal of Vision June 2006, Vol.6, 583. doi:10.1167/6.6.583
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      Charles C.-F. Or, Sieu K. Khuu, Anthony Hayes; The effect of contrast variations on the perception of Glass patterns. Journal of Vision 2006;6(6):583. doi: 10.1167/6.6.583.

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

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Abstract

The perception of global structure of a static concentric Glass pattern is difficult, but not impossible, when its dot-pairs are of opposite polarity (see, e.g., Badcock, Clifford, & Khuu, 2005). We investigated whether the addition of motion signals enhance extraction of local orientation from opposite-polarity dot-pairs. The stimuli were random-dot patterns (radius: 14 deg visual arc) consisting of 200 dot-pairs (dot width: 5 min; length of pair: 20 min) orientated along circular trajectories, or at random orientations, on a background at 45.5 cd m−2 luminance. For each dot-pair, one dot was always light increment (90.9 cd m−2), and the other was varied over conditions in the range between 0.0718 cd m−2 and 90.9 cd m−2 (i.e., Weber contrast from approx. −1 to 1). The dot pairs were either stationary (static condition), or randomly re-positioned at a rate of 17 Hz (dynamic condition) in a 1.06 s stimulus presentation. The observer's task was to identify the interval containing the circular structure in a temporal two-interval forced-choice procedure. The detection threshold for each contrast difference within the dot-pair was determined by an adaptive staircase. The results showed that perception of global structure is more salient with dynamic than with static Glass patterns regardless of variations in contrast, and for dynamic presentations salience improvement was greater for opposite-polarity than for same-polarity patterns. These findings suggest that motion processing mechanisms are more capable than form processing mechanisms in tolerating contrast differences for the perception of global structure.

Or, C. C.-F. Khuu, S.K. Hayes, A. (2006). The effect of contrast variations on the perception of Glass patterns [Abstract]. Journal of Vision, 6(6):583, 583a, http://journalofvision.org/6/6/583/, doi:10.1167/6.6.583. [CrossRef]
Footnotes
 Supported by Grant HKU7149/02H from the Research Grants Council of Hong Kong, and partly by a research grant to C. Or from the Canadian Institutes of Health Research.
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