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Charles Chubb, Joshua A. Solomon, Michael J. Morgan; Evidence for plaid-grabbers. Journal of Vision 2006;6(6):201. doi: 10.1167/6.6.201.
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We wondered whether plaids activate preattentive mechanisms distinct from those activated by their component gratings. Observers searched for a target plaid—the sum of two perpendicular components in a circular window (radius = 0.65 deg). The target was present on half the trials. On target-present trials, approximately half of the three or seven distractors were one component (frequency f1), the rest were the other component (frequency f2). Target and distractors were evenly arrayed on a circle (radius 2.36 deg) around fixation. Target and distractor contrasts were randomly perturbed. When f1 = 2 c/d and f2 = 5.25 c/d, reaction times increased with the number of distractors (15.75 ms/item). When f1 = f2 = 5.25 c/d, the set-size effect was much smaller (2.35 ms/item). When f1 = f2 = 2.00 c/d, reaction times did not increase with the number of distractors. These results suggest the existence of “plaid-grabbers”: preattentive, plaid sensitive mechanisms with bandlimited input that do not respond to individual plaid components.
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