A two-stage search of visual working memory: investigating speed in the change-detection paradigm
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A popular procedure for investigating working memory processes has been the visual change-detection procedure. Models of performance based on that procedure, however, tend to be based on performance accuracy and treat working memory search as a one-step process, in which memory representations are compared to a test probe to determine if a match is present. To gain a clearer understanding of how search of these representations operate in the change-detection task, we examined reaction time in two experiments, with a single-item probe either located centrally or at the location of an array item. Contrary to current models of visual working memory capacity, our data point to a two-stage search process: a fast first step to check for the novelty of the probe and, in the absence of such novelty, a second, slower step to search exhaustively for a match between the test probe and a memory representation. In addition to these results, we found that participants tended not to use location information provided by the probe that theoretically could have abbreviated the search process. We suggest some basic revisions of current models of processing in this type of visual working memory task.
KeywordsVisual working memory Memory search Change-detection Reaction time
This research was funded by NIH Grant R01 HD-21338 to Cowan and NIA Training Grant T32 AG000175-21 (Georgia Institute of Technology). We wish to thank Scott Saults for assistance with programming. Address correspondence to Amanda Gilchrist, Department of Psychology, Cottey College, Nevada, MO 64772, USA, or to Nelson Cowan, Department of Psychological Sciences, University of Missouri, Columbia, MO 65211, USA. E-mail: firstname.lastname@example.org or CowanN@missouri.edu.
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