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Caroline Barras, Dirk Kerzel; Interference from salient-but-irrelevent stimuli is stronger with perceptual ambiguity: Evidence for biased competition. Journal of Vision 2016;16(12):1005. doi: 10.1167/16.12.1005.
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© 2017 Association for Research in Vision and Ophthalmology.
We investigated how interference from salient distractors is affect by target-nontarget similarity. We presented eight shapes and participants searched for a square target among diamond nontargets in the high similarity condition and for a square target among circle nontargets in the low similarity condition. Participants had to indicate the orientation of the bar inside the square by pressing one of two keys. A color distractor was present on 50% of the trials. Results showed that interference from the color distractor was larger in the high than in the low similarity condition. Additionally, we measured event-related potentials. The strong interference in the high similarity condition was accompanied by a contralateral negativity, the N2pc component, in response to the distractor. In contrast, weak interference in the low similarity condition was accompanied by a contralateral positivity, the PD component, in response to the distractor. Previously, the N2pc component was considered a measure of attentional capture whereas the distractor positivity (PD) was assumed to reflect attentional suppression. Our findings suggest that the salient-but-irrelevant distractor wins the initial competition for selection when nontargets match the attentional template for the target and perceptual ambiguity is therefore high. In contrast, when the nontargets were a poor match to the attentional template, the salient element could be suppressed. Our study is important with respect to recent claims that saliency signals are suppressed when they are irrelevant. Our results show that suppression of salient-but-irrelevant distractors is only possible when visual search is efficient and perceptual ambiguity therefore low.
Meeting abstract presented at VSS 2016
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