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Hwan Cui Koh, Elizabeth Milne, Karen Dobkins; Development of direction-of-motion discrimination to detection threshold ratios (MOT/DET) for luminance (Light/Dark) and chromatic (Red/Green) stimuli: Infants, adolescents and adults. Journal of Vision 2009;9(8):1060. doi: https://doi.org/10.1167/9.8.1060.
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© ARVO (1962-2015); The Authors (2016-present)
Background: The use of luminance versus chromatic information for motion processing has been quantified by comparing the contrast threshold for discriminating direction of a moving grating (MOT), to the contrast threshold for detecting that same moving grating (DET), producing a MOT/DET ratio. Adults exhibit MOT/DET ratios near 1.0 for luminance gratings, but closer to 2.0–4.0 for chromatic gratings, suggesting that luminance information provides stronger input to motion mechanisms than chromatic information. By contrast, infants exhibit MOT/DET ratios that are comparable for luminance and chromatic gratings, suggesting that in early development luminance and chromatic information provide equal input to motion. The current study tested adolescents and adults to more finely track developmental changes in MOT/DET ratios from infancy to adulthood.
Method: Data were collected from 12–15 year-olds, 15–17 years-olds and adults, and were compared to data previously obtained from 3 month-olds (Dobkins & Teller, 1996). The stimuli were moving luminance (light/dark) and chromatic (red/green) horizontal gratings (1.0cpd, 5.5Hz, subtending 2.0×2.0°). In the MOT task, a single interval was presented and participants indicated whether the grating moved up or down. In the DET task, participants indicated in which of two intervals the moving grating was presented. The relative contribution of luminance versus chromatic information for motion processing is measured by the difference in log MOT/DET ratios for luminance and chromatic gratings (Diff-Ratio), with values [[gt]] 0 indicating stronger luminance versus chromatic input to motion processing.
Results: Mean Diff-Ratios increased significantly with age (F(3,88)=7.23, pConclusion: The relative input of luminance versus chromatic information to motion processing changes over the course of development, with a relative decline in chromatic input. This pattern of asymmetry becomes adult-like by 15 years of age.
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