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Eduard Ort, Johannes Fahrenfort, Christian Olivers; Control over target selection determines switch costs in multiple-target search.. Journal of Vision 2016;16(12):1287. doi: 10.1167/16.12.1287.
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© ARVO (1962-2015); The Authors (2016-present)
Visual selection of task-relevant objects is guided by a search template, a mental representation of a current search target that is assumed to be stored in working memory. Currently, it is debated whether one can have more than a single active search template that guides visual selection at any given moment. By demonstrating the absence of costs in fixation duration while scanning a search display for items that match one of two potential search templates, recent evidence suggests that one can look for multiple items simultaneously. Here, we investigated this issue further by applying a recently developed eye tracking paradigm. Crucially, subjects were instructed to look for two targets simultaneously while we manipulated the degree to which they had control over target selection. In a series of three experiments, we (1) show that switch costs disappear when instructing subjects to search for two target colors simultaneously, but only when subjects have full control over target selection (i.e., they choose at will which target color to select from the set of presented stimuli). However, (2) as soon as subjects lose control over the selection process, switch costs appear, showing that the emergence of switch costs depends on the degree to which one is in control of target selection. This suggests that the absence of switch costs in previous two-template experiments is caused by efficient template switching during search rather than having two templates active at the same time.
Meeting abstract presented at VSS 2016
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