September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Foveal and peripheral crowding and contour interaction are not affected by flanker-target color congruency
Author Affiliations & Notes
  • Stephanie Marten-Ellis
    College of Optometry, University of Houston, Houston, Texas, United States
  • Harold E. Bedell
    College of Optometry, University of Houston, Houston, Texas, United States
  • Scott B Stevenson
    College of Optometry, University of Houston, Houston, Texas, United States
  • Footnotes
    Commercial Relationships   Stephanie Marten-Ellis, None; Harold Bedell, None; Scott Stevenson, None
  • Footnotes
    Support  short-term training grant T35 EY07088
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 1516. doi:
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      Stephanie Marten-Ellis, Harold E. Bedell, Scott B Stevenson; Foveal and peripheral crowding and contour interaction are not affected by flanker-target color congruency. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1516.

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

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Abstract

Purpose : Previous studies disagree as to whether visual performance is impaired more by flanking stimuli that have the same (congruent) vs. a different (incongruent) color as the target to be identified. In this study, we compared the effect of color congruent and incongruent flankers and targets on the magnitude and extent of crowding (CW) and contour-interaction (CI) in foveal and peripheral vision.

Methods : Single Sloan letters were presented at the fovea or at 5 deg in the inferior visual field, with and without flanking bars or letters placed symmetrically to the right, left, top and bottom. Flanking bars or letters were either color congruent (red-red or green-green) or incongruent (red-green or green-red) with respect to the target letter. All targets and flankers had approximately equal Weber color contrast (-79%). At each eccentricity, the target size was chosen so that each subject (n=4) could identify the letters with ~80% accuracy in the absence of flankers. Edge-to-edge flanker-to-target distance varied from 10 – 200% of the letter size. The magnitude and extent of foveal and peripheral CW and CI were defined from plots of percent correct letter identification vs. target-to-flanker distance, separately for color congruent and incongruent stimuli.

Results : Plots of foveal CW and CI were similar and showed no difference between the color congruent and incongruent conditions. At an eccentricity of 5 deg, both the magnitude and extent of CW were greater than CI, as reported previously. As in the fovea, no differences in CW or CI were found at 5 deg for color congruent vs. incongruent stimuli.

Conclusions : The results suggest that grouping by color does not significantly influence the mechanisms that mediate CW or CI. The data also indicate that CW and CI depend on different underlying mechanisms in the fovea and periphery and that the most relevant input to these mechanisms is luminance rather than chromatic contrast.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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