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| Volume 7, Number 4, Article 9, Pages 1-11 |
doi:10.1167/7.4.9 |
http://journalofvision.org/7/4/9/ |
ISSN 1534-7362 |
Orientation discrimination in 5-year-olds and adults tested with luminance-modulated and contrast-modulated gratings
Terri L. Lewis |
Department of Psychology, Neuroscience & Behaviour, McMaster University,
Hamilton, Canada |
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Andrea Kingdon |
Department of Psychology, Neuroscience & Behaviour, McMaster University,
Hamilton, Canada |
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Dave Ellemberg |
Département de Kinésiologie, Université de Montréal, Montréal, Canada, & Centre de Recherche en Neuropsychologie Expérimental et Cognition, Montréal, Canada |
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Daphne Maurer |
Department of Psychology, Neuroscience & Behaviour, McMaster University,
Hamilton, Canada |
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Abstract
We compared thresholds for discriminating orientation by 5-year-olds and adults for first-order (luminance-modulated) and second-order (contrast-modulated) gratings. To achieve equal visibility, we set the contrast for each age and condition at a fixed multiple of the contrast threshold for discriminating horizontal from vertical gratings. The minimum tilt that could be discriminated from vertical was four to five times larger in 5-year-olds than in adults, even when the noise was removed from the first-order stimuli and amplitude modulation increased to 0.90. Thresholds at both ages were significantly worse (1.2–1.5 times worse) for second-order modulation than for equally visible first-order modulation, and 5-year-olds were equally immature for both types of pattern. Together, the findings suggest that orientation discrimination is slow to develop and worse for second-order than first-order patterns in both children and adults.
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