August 2009
Volume 9, Issue 8
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Vision Sciences Society Annual Meeting Abstract  |   August 2009
Impaired luminance detection in apparent motion trajectory
Author Affiliations
  • Souta Hidaka
    Department of Psychology, Graduate School of Arts & Letters, Tohoku University
  • Masayoshi Nagai
    National Institute of Advanced Industrial Science and Technology (AIST)
  • Patrick J. Bennett
    Department of Psychology, Neuroscience & Behaviour, McMaster University, and Centre for Vision Research, York University
  • Allison B. Sekuler
    Department of Psychology, Neuroscience & Behaviour, McMaster University, and Centre for Vision Research, York University
  • Jiro Gyoba
    Department of Psychology, Graduate School of Arts & Letters, Tohoku University
Journal of Vision August 2009, Vol.9, 687. doi:10.1167/9.8.687
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      Souta Hidaka, Masayoshi Nagai, Patrick J. Bennett, Allison B. Sekuler, Jiro Gyoba; Impaired luminance detection in apparent motion trajectory. Journal of Vision 2009;9(8):687. doi: 10.1167/9.8.687.

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Abstract

Yantis & Nakama (1998) found that letter discrimination was impaired when the letter fell within the path of an apparent motion (AM) trajectory of a spot. Thus, the internal representation of AM stimuli can interfere with perception at a relatively high processing stage (letter discrimination). Here, we investigated whether AM interference also occurs at an earlier processing stage (pattern detection). We presented two square inducers (1×1 deg) at 5 deg below a fixation cross, separated horizontally by 5 deg. The inducer durations and interstimulus intervals (ISIs) were 106 ms. Background luminance was 30 cd/m2; the inducers' Weber contrast was 100%. In the On-AM-path condition, a target of identical shape and dimension as the inducers was presented for 26 ms in-between inducers. In the Off-AM-path condition, the vertical positions of the target and inducers differed by 2 deg. In the FL condition, the inducers flickered so that AM was not perceived. Five observers conducted a target detection task. Two interleaved staircases varied target contrast across to estimate the 50 % detection threshold. We found that threshold in the On-AM-path condition was higher (contrast: 37.9 %) than threshold in the Off-AM-path (contrast: 17.1 %) and FL (contrast: 13.3 %) conditions. Similar results were obtained when the inducers and target had negative contrasts (On-AM-path: −53.3 %; Off-AM-path: −19.2 %; FL: −15.8 %), and when the contrast of the target was negative and that of the inducers was positive (On-AM-path: −27.6 %; Off-AM-path: −13.5 %; FL: −15.9 %). These findings suggest that AM stimuli affect early visual processes involved in detecting a luminance increment or decrement and that the internal representation of AM stimuli reflects the stimulus's attribute (contrast polarity).

Hidaka, S. Nagai, M. J. Bennett, P. Sekuler, A. B. Gyoba, J. (2009). Impaired luminance detection in apparent motion trajectory [Abstract]. Journal of Vision, 9(8):687, 687a, http://journalofvision.org/9/8/687/, doi:10.1167/9.8.687. [CrossRef]
Footnotes
 This study was supported by Grant-in-Aid for scientific research from the Japan Society for the Promotion of Science to SH (No. 19004400).
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