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Halely Balaban, Trafton Drew, Roy Luria; Visual working memory resetting is triggered by a loss of objects-to-representations correspondence. Journal of Vision 2017;17(10):1282. doi: 10.1167/17.10.1282.
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© ARVO (1962-2015); The Authors (2016-present)
Visual working memory (VWM) representations are modified when the represented items change. This updating process relies on an ongoing correspondence between each VWM-representation and a specific object in the environment, thereby enabling access to the correct representation. Importantly, we argue that when this correspondence breaks, VWM cannot update, and must instead reset: discard the existing representations and start anew. We aimed to establish the loss of the objects-to-representations mapping as a necessary and sufficient condition for the resetting process, by demonstrating that when (and only when) this mapping breaks, VWM will reset. First, we demonstrate that similar manipulations trigger either resetting or updating, depending on whether the correspondence could be maintained. In a shape change-detection paradigm, we presented black polygons that moved and could separate into halves. The movement was task-irrelevant, but established a correspondence between the moving polygon and a single representation. The separation broke the correspondence, because afterwards VWM had to track each half independently (requiring two correspondences), triggering a resetting process. The contralateral delay activity, an electrophysiological marker whose amplitude rises as more items are held in VWM, sharply dropped, indicating a loss of VWM-contents. Conversely, when the pre-separation correspondence supported a separate mapping for each half (by presenting each in a different, task-irrelevant, color), VWM could maintain the mapping during the separation, resulting in updating instead of resetting. Second, using behavioral measures we demonstrate that VWM is blind to salient changes occurring during resetting: when the shape of a moving polygon changed concurrently with its separation (i.e., during resetting), subjects missed this change. This is presumably because the representations cannot be accessed, since there is no valid correspondence. Critically, we demonstrate that the effect is limited only to the item whose correspondence is broken, while similar changes in a nearby unseparated polygon were easily detected.
Meeting abstract presented at VSS 2017
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