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Andrew McCollough, Edward Vogel; Control processes in working memory. Journal of Vision 2006;6(6):32. doi: 10.1167/6.6.32.
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© ARVO (1962-2015); The Authors (2016-present)
Visual working memory is a highly capacity limited system maintaining only three to four objects at a time. This limitation requires mechanisms which facilitate the continual updating of the contents of working memory, which involves the addition of new items and the deletion of old items from being held in this limited space. Here we report a neurophysiological measure of this memory updating mechanism in humans. Using a visual running memory span task while simultaneously recording event related potentials we observe that the appending of sub-capacity arrays items into working memory is perfectly additive, and remains additive irrespective of temporal and spatial gaps. That is, the mean contralateral delay activity (CDA) amplitude for an array size of four is equivalent whether the items are all presented in a single array or distributed across sequential arrays, as well as whether the sequential array items appear at the same location or in different locations. The appending process also appears to be independent of maintenance mechanisms of working memory, such that there were no latency costs for adding items into working memory when the subject was already holding items in memory. Furthermore, we examined the process of voluntarily deleting of items from working memory by “swapping” them with new items and found that the efficiency of this aspect of updating is predicted by an individual's particular memory capacity.
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