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Jeff Moher; Salient distractors speed responses when targets are absent in visual search. Journal of Vision 2017;17(10):942. doi: 10.1167/17.10.942.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptually salient distractors frequently capture attention. In most research on this phenomenon, attention capture is measured by asking participants to identify a target on each trial, and comparing performance as a function of whether a salient distractor was present or not. However, in many real world search tasks such as medical image screening, targets are often absent. I examined the impact of salient distractors on search trials in which participants had to press a key to indicate whether or not a target was present. Three factors were varied randomly and orthogonally across trials: set size (4 vs. 8), salient distractor (present vs. absent), and target (present vs. absent). As expected, on target present trials, response times (RTs) were longer when a salient distractor was present than when it was absent. However, on target absent trials, RTs were shorter when a salient distractor was present. One possible explanation is that salient distractors may reduce quitting thresholds; that is, participants are more likely to assume that no target is present when a salient distractor is present. Consistent with this view, miss rates on target present trials were higher when salient distractors were present. This effect was robust across multiple experiments, as salient distractors produced shorter RTs on target absent trials when targets were rare (Experiment 2), and when accuracy feedback was provided after each trial (Experiment 3). Ongoing eye-tracking experiments will shed further light on the mechanism by which these distractor-induced speeded RTs occur. Together, these data shed new light on the mechanisms by which salient distractors impact performance. These results have important implications not only for models of attention, but also for real world search tasks in which targets may be absent, and distractions may occur.
Meeting abstract presented at VSS 2017
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