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Ben Park, Dirk B. Walther, Keisuke Fukuda; Dynamic Representations in Visual Working Memory. Journal of Vision 2020;20(11):900. doi: https://doi.org/10.1167/jov.20.11.900.
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© ARVO (1962-2015); The Authors (2016-present)
Despite people’s subjectively rich visual experiences, the amount of information they can actively represent in their minds at a given time is severely limited by the capacity of visual working memory (VWM). To characterize this cognitive bottleneck, past studies have primarily employed static visual stimuli and, therefore, it is not yet clear how VWM represents dynamically changing visual information. Previous research suggests that VWM might utilize two distinct mechanisms to maintain an active representation of a changing stimulus: When a stimulus goes through a continuous (e.g., gradual) change, VWM keeps up with the change by updating its existing representation of the original stimulus. When a stimulus goes through a discontinuous (e.g., sudden) change, VWM resets its content by first discarding its original representation of the stimulus and then re-encoding a new representation. To test this hypothesis, we measured an electrophysiological correlate of VWM load (the contralateral delay activity or CDA) while participants tracked the characterizing identity (e.g., shape, color) of a dynamically changing stimulus. Here, we predicted that 1) the CDA amplitude remains sustained when a target object goes through a continuous identity change and 2) the CDA amplitude reduces to zero shortly after a target object goes through a discontinuous identity change. Our experiments confirmed both of our hypotheses when the stimulus went through dynamic shape or color changes. Taken together, our findings provide support for the existence of two distinct mechanisms through which VWM keeps track of dynamically changing visual information; updating and resetting.
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