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Cody McCants, Tobias Katus, Martin Eimer; Comparing the capacity limitations of working memory for locations and features. Journal of Vision 2018;18(10):695. doi: 10.1167/18.10.695.
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© ARVO (1962-2015); The Authors (2016-present)
The capacity of working memory (WM) is limited, both in terms of the number of items that can be simultaneously stored and the precision of stimulus representations in WM. Previous studies using electrophysiological recordings have found that the amplitude of event-related contralateral delay activity (CDA) during the retention of visual information in WM reflects the number of items being memorized, up to an asymptote at around 3 items. This is usually interpreted as evidence for a discrete capacity limitation of WM. However, because these CDA results were obtained in tasks requiring memory for features or objects, it is unknown whether the same discrete capacity limits also apply to WM for spatial locations. To answer this question, we compared memory performance and CDA amplitudes in two tasks where participants either had to memorize the colours or the spatial locations of items. WM load was manipulated for both tasks (1, 2, 3 or 4 items). CDA amplitudes increased with the number of memorized items, up to an asymptote of 3 items. Importantly, identical load-dependent CDA enhancements were observed in the colour and location tasks (i.e., no task type x load interaction), as confirmed by Bayesian analysis. This was mirrored in task performance, where K-estimates of memory capacity were similar in both tasks. These results suggest that the same discrete capacity limits that apply to WM for non-spatial features also constrain the number of locations that can be held in WM. This raises important questions about the role of spatial location for representations of objects and features in WM.
Meeting abstract presented at VSS 2018
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