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Vickie Armstrong, Terri Lewis, Daphne Maurer; The development of sensitivity to first- and second-order pattern versus motion. Journal of Vision 2007;7(9):38. doi: 10.1167/7.9.38.
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We measured sensitivity to first- and second-order pattern and motion in 5-, 7-, and 10-year-old children and in adults. Luminance (FO) and contrast (SO) were modulated over trials to measure the minimum modulation yielding 82% correct responses. We measured thresholds for four different conditions: the discrimination of the orientation (horizontal vs. vertical) of a stationary pattern and the discrimination of direction of motion (left vs. right) for three different combinations of temporal frequency (TF) and velocity (V): TF = 6 Hz, V=6 d/s; TF = 1.5 Hz, V = 6 d/s; TF = 1.5 Hz, V = 1.5 d/s. Adults and children (n=56/age grp) provided individual thresholds for one of the four conditions and for both types of stimuli (FO & SO). At all ages, observers were more sensitive to SO pattern than to SO motion, but showed the opposite for FO stimuli (ps[[lt]]0.001). This suggests that information about pattern is necessary to discriminate the direction of SO but not FO motion, as would be expected if SO motion, but not FO motion, is processed using a feature tracking mechanism (Seiffert & Cavanagh, 1998). For SO stimuli, children achieved adult-like thresholds by 7 years of age for all four conditions. Surprisingly, for FO motion, their thresholds for pattern discrimination were not adult-like until 10 years of age and even at that age, they were still immature at discriminating the direction of motion in one condition: TF =1.5 Hz, V=6 d/s (p[[lt]]0.001). The finding of earlier maturity for some conditions of SO than FO stimuli is consistent with recent findings in monkeys (Kiorpes, Gavlin, & El-Shamayleh, 2006).
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