Selecting and ignoring salient objects within and across dimensions in visual search
Schubo, A. and Muller, Hermann J. (2009) Selecting and ignoring salient objects within and across dimensions in visual search. Brain Research 1283 , pp. 84-101. ISSN 0006-8993.
There are two strategies for selecting relevant information from a visual scene: according to either its salience or its relevance for behavioral goals. Although there is broad evidence for the existence of both mechanisms, there has been a debate concerning the impact of top-down control on salience-based selection. We investigated whether salient but irrelevant information is filtered by the visual system and what role the organization of the visual system plays in selection. Using event-related brain potentials (ERPs), we compared processing of the same salient objects when relevant versus irrelevant to the task at hand. Observers had to detect a target singleton defined in a specific dimension (e.g., orientation), while ignoring a singleton non-target defined in either another dimension (e.g., color; Experiment 1, requiring dimension-based search) or the same dimension (Experiment 2, requiring feature-based search). For dimension-based search, the results revealed an enhanced posterior N2, indicative of singleton selection, and an enhanced P3 for target singletons, but no difference between non-target singletons defined in another dimension and blank trials. Also, N2pc results indicated that the allocation of attention was modulated by the task. In contrast, for feature-based search, some ERP enhancement was also observed for non-target singletons (defined in the same dimension as the target) in the N2, N2pc, and P3 latency ranges. This pattern argues in favor of a strong top-down influence on singleton selection that operates on dimensions rather than features.
|Keyword(s) / Subject(s):||Attention guidance, bottom-up selection, top-down selection, dimension-specific processing, posterior N2, N2pc|
|School:||Birkbeck Schools and Departments > School of Science > Psychological Sciences|
|Date Deposited:||22 Dec 2010 14:08|
|Last Modified:||17 Apr 2013 12:19|
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