June 2006
Volume 6, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2006
Orientation discrimination in noise: 7-year-olds are noisier than adults
Author Affiliations
  • Terri L. Lewis
    McMaster University, HamiltonCanada
  • Dorita H. F. Chang
    McMaster University, HamiltonCanada
  • Kathryn M. Murphy
    McMaster University, HamiltonCanada
  • Daphne Maurer
    McMaster University, HamiltonCanada
  • David G. Jones
    McMaster University, HamiltonCanada
Journal of Vision June 2006, Vol.6, 380. doi:10.1167/6.6.380
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      Terri L. Lewis, Dorita H. F. Chang, Kathryn M. Murphy, Daphne Maurer, David G. Jones; Orientation discrimination in noise: 7-year-olds are noisier than adults. Journal of Vision 2006;6(6):380. doi: 10.1167/6.6.380.

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

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Abstract

We used a new high contrast stimulus containing a variable amount of orientation signal in unoriented noise (Jones et al., 2003) to test orientation discrimination in visually normal 7-year-olds and adults (n = 16/grp). The task on each trial was to indicate whether the signal was oriented horizontally or vertically. Percent signal was varied according to a QUEST staircase procedure and thresholds were taken as the lowest orientation signal for which performance was 82% correct. Across 4 runs, stimulus size decreased systematically from 6 − 0.75 deg. In a 5th run, we retested the 6 deg stimulus to rule out fatigue effects. Thresholds were higher in children than in adults and varied with stimulus size (ANOVA, p < .0002 for both). Specifically, at both ages, thresholds improved as size increased from 0.75 – 3 deg (p < .005 for all) and then reached an asymptote, showing no further improvement beyond 3 deg (p > .70). At asymptote, children required 18% signal to discriminate orientation accurately whereas adults required only 12%, indicating that intrinsic noise may be 1.5 times higher in 7-year-olds than in adults. Because contrast sensitivity and motion coherence thresholds are mature by 7 years of age (Ellemberg et al., 1999, 2002), the ability to extract a stationary oriented signal from noise likely involves different neural mechanisms that mature more slowly.

Lewis, T. Chang, D. H. F. Murphy, K. M. Maurer, D. Jones, D. G. (2006). Orientation discrimination in noise: 7-year-olds are noisier than adults [Abstract]. Journal of Vision, 6(6):380, 380a, http://journalofvision.org/6/6/380/, doi:10.1167/6.6.380. [CrossRef]
Footnotes
 Support: CIHR grants MOP-36430 & MOP-13624 NSERC grant 175437-05.
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