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Girish Kumar, Susana T. L. Chung; Saccades affect crowding, but crowding does not affect saccades. Journal of Vision 2013;13(9):580. doi: 10.1167/13.9.580.
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Aim: Recent research has shown a close association between saccades and crowding, specifically saccades reduce crowding. However, does crowding affect saccades? The aim of this study was to investigate the effects of crowding on the dynamics of saccades. Methods: We compared the dynamics of saccades (amplitudes, latencies, accuracy and precision of landing positions) when subjects (N=3) executed saccades to the center of a stimulus target, located at either 10° in the lower visual field or 10° in the lower-right visual field. Different types of stimuli were tested: a 0.25°[sup] [/sup]square, single letters, random sequences of three letters (trigrams), a small and a large solid rectangle and a small and a large Gaussian blob. Letters were rendered in Times New Roman with x-height = 0.75°. The size (and standard deviation) of the small and large rectangles and Gaussian blobs matched the average size of a single letter and a trigram, respectively. Eye movements were monitored using an Eyelink II at a sampling frequency of 250 Hz. Saccades were identified using a velocity criterion of 75 °/second. To ensure that subjects experienced crowding at both testing locations, we separately measured letter identification accuracy for single letters and for the middle letters of trigrams, presented for 150 ms. Results: On average, performance accuracy dropped from 99% for identifying single letters to 40–55% for identifying the middle letters of trigrams, confirming that our letter-stimulus conditions were effective in inducing crowding. However, there was no difference in any of the parameters of the dynamics of saccades between the single-letter and the trigram conditions. In fact, none of the parameters of the dynamics of saccades were statistically different across the different stimulus types (p>0.05 after Bonferroni corrections). Conclusions: While saccades affect crowding perceptually, the reverse is not true. Specifically, crowding does not alter the dynamics of saccades.
Meeting abstract presented at VSS 2013
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