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Maria Lev, Uri Polat; Reaction time as a predictive marker for crowding. Journal of Vision 2015;15(12):106. doi: 10.1167/15.12.106.
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© ARVO (1962-2015); The Authors (2016-present)
Visual crowding, the inability to recognize objects in clutter, limits visual perception, conscious, and object recognition throughout most of the visual ﬁeld. Crowding is measured as a reduction of the target’s performance such as letter identification in the presence of flankers. We recently showed (Lev, Yehezkel, and Polat, Scientific Reports 2014) that foveal crowding may be absent for long presentation times but is evident for short times. However, the reaction time (RT) is remarkably slower under crowded conditions even without reduced accuracy. Since RT and response accuracy are used to explore the processing load, we hypothesized that RT can serve as a marker for processing the load imposed by spatial crowding. We asked subjects to identify the letter E embedded in a matrix of other letters for presentation times from 30 to 240 msec. The results show that foveal crowding is remarkable for short presentation times of 30 and 60 msec but is insignificant for 240 msec. However, RT was largely slower (~100 msec) even in cases without reduced accuracy (no crowding effect). Furthermore, RT for 240 msec predicts crowding effect for a more demanding task; for subjects that exhibit a slower RT for 240 msec, a larger crowding effect is measured for the shorter durations. Therefore, a slower RT can serve as a marker for an implicit increase in processing load to overcome reduced accuracy, suggesting reduced processing speed in crowding; hence it can be regarded as temporal crowding. Recently our perceptual learning studies showed that training improves the processing speed (Lev, Ludwig, Gilaie-Dotan, et al., Scientific Reports, 2014), thus enabling the crowding to be overcome for shorter presentation times. Hence, improved temporal crowding may be followed by reduced spatial crowding, thus eliminating "bottlenecks" for further cognitive tasks.
Meeting abstract presented at VSS 2015
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