October 2003
Volume 3, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   October 2003
Reduced contrast does not reduce visual crowding
Author Affiliations
  • Elisabeth M. Fine
    SERI/Harvard Medical School; USA
Journal of Vision October 2003, Vol.3, 814. doi:10.1167/3.9.814
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      Elisabeth M. Fine; Reduced contrast does not reduce visual crowding. Journal of Vision 2003;3(9):814. doi: 10.1167/3.9.814.

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

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Abstract

Background: Previous studies have reported reduced crowding for low contrast stimuli (Kothe & Regan, 1990: Optom Vis Sci; Simmers et al., 1999: Ophthal Physiol Opt). Both defined crowding as a change in acuity for single vs. flanked letters, and used foveal viewing. This study sought to confirm these findings using a more traditional crowding task (i.e. comparison of single and flanked letter identification at different retinal eccentricities). Methods: 10 observers (18–34 yo; VA 20/14) identified 0.34 deg letters and letters flanked by an ‘x’ on either side (xax) at fixation and ±1, 3, 5, and 7 letter spaces (±0.34, ±1.02, ±1.70, and ±2.38 deg) from fixation on the horizontal meridian. All 25 letters (other than x) were presented at each location; letter and position were randomly selected from trial-to-trial. In separate blocks, the stimuli were ∼100, 30, and 10% contrast. Crowding was defined as the difference between single letter and flanked letter performance. Results: There was little difference in crowding for the three contrasts. Averaged across position, there was 14±0.3, 15±0.1, and 19±0.2% crowding for the 100, 30, and 10% contrasts, respectively [F(2, 18) = 2.3, p = 0.127]. There was little change from 100% contrast for single or flanked letters presented with 30% contrast, but with 10% contrast, performance was significantly reduced for both stimulus types. Accuracy was similar across positions for single letters presented with 10% contrast and flanked letters presented with 100% contrast. Conclusions: Unlike previous reports, these data show no change in crowding with reduced contrast stimuli. It is possible that 10% is not sufficiently reduced for crowding to disappear, but Kothe and Regan showed reduced crowding for 11% contrast stimuli. The data suggest that the effect of flanking letters may be to reduce the effective contrast of the target letters.

Fine, E. M.(2003). Reduced contrast does not reduce visual crowding [Abstract]. Journal of Vision, 3( 9): 814, 814a, http://journalofvision.org/3/9/814/, doi:10.1167/3.9.814. [CrossRef]
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