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Dirk Kerzel, Caroline Barras; Active suppression of salient-but-irrelevant inputs takes time and does not underlie resistance to interference. Journal of Vision 2016;16(12):1004. doi: https://doi.org/10.1167/16.12.1004.
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© ARVO (1962-2015); The Authors (2016-present)
We investigated the electrophysiological correlates of resistance to interference from salient-but-irrelevant color singletons. In conditions promoting interference, the target shape was presented among uniform nontargets. Because it was possible to search for any salient singleton instead of a specific shape (singleton detection mode), participants may have selected the color distractor on some trials, which increased reaction times. In conditions avoiding interference, the target shape was embedded in various nontarget shapes (feature search mode), requiring observers to search for a specific shape. We measured event-related potentials (ERPs) to lateralized color singletons in singleton detection and feature search modes. In singleton detection mode, we observed a contralateral positivity (PD) after about 290 ms, suggesting that the salient distractor was suppressed. Because RTs in singleton detection mode increased when a distractor was present, we conclude that active suppression of distractors is a time-consuming process. In feature search mode, neither a PD nor an N2pc occurred, suggesting that the absence of interference is not accomplished by active suppression of salient-but-irrelevant stimuli, but by ignoring them. Further, we observed an early positivity (Ppc) to the color distractor between 125 and 175 ms that is consistent with an "attend-to-me" signal. Finally, the latency of the ERPs were consistent with the summation of the distractor-related PD and the target-related Nt.
Meeting abstract presented at VSS 2016
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