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An electrophysiological assessment of distractor suppression in visual search tasks

Authors

  • Veronica Mazza,

    1. Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
    2. Department of Cognitive Sciences and Education, University of Trento, Trento, Italy
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  • Massimo Turatto,

    1. Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
    2. Department of Cognitive Sciences and Education, University of Trento, Trento, Italy
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  • Alfonso Caramazza

    1. Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
    2. Cognitive Neuropsychology Laboratory, Harvard University, Cambridge, USA
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  • This research has been supported by a grant from the Fondazione Cassa di Risparmio di Trento e Rovereto, Italy, and from the Ministero dell'Istruzione, dell'Università e della Ricerca, Italy.

Address reprint requests to: Veronica Mazza, Corso Bettini 31, 38068 Rovereto, Italy. E-mail: veronica.mazza@unitn.it

Abstract

We investigated whether the N2pc is unequivocally linked to distractor-suppression mechanisms, as is commonly assumed. According to the distractor-suppression account of the N2pc, no suppression, and thus no N2pc, should occur when homogeneous distractors help in selecting the target, such as when the target feature is unpredictable. Participants performed a simple detection or a finer discrimination on a singleton target, which had either a variable or a constant color. Contrary to the distractor-suppression account, an N2pc was present for both the variable and the constant conditions, and for both tasks. Additionally, target feature consistency correlated with earlier N2pc onsets relative to variable blocks. Both results indicate that the N2pc is not unequivocally linked to distractor-suppression mechanisms, but may index mechanisms involved in identifying and localizing relevant stimuli through enhancement of their features.

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