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Comparative Study
. 2011 Nov;22(11):1434-41.
doi: 10.1177/0956797611417006. Epub 2011 Oct 10.

The number and quality of representations in working memory

Weiwei Zhang  1 , Steven J Luck
Affiliations
Comparative Study

The number and quality of representations in working memory

Weiwei Zhang et al. Psychol Sci. 2011 Nov.

Abstract

Flexible-resource theories characterize working memory as a flexible resource that can store either a large number of low-quality representations or a small number of high-quality representations. In contrast, limited-item theories propose that the number of items that can be stored in working memory is strictly limited and cannot be increased by decreasing the quality of the representations. We tested these fundamentally different conceptualizations of working memory capacity by determining whether observers could trade quality for quantity in working memory when given incentives to do so. We found no evidence that observers could increase the number of representations by decreasing their quality in working memory, but observers could make such a trade-off at earlier processing stages. Our results show that the capacity limit of working memory is best characterized as a limit on the number of items that can be stored and not as a limit on a finely divisible resource that simultaneously determines the number and quality of the representations.

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Figures

Figure 1
Figure 1
(a) Trial structure in the high-precision condition of Experiment 1a. (b) Example test display in the low-precision condition with 9 spokes. (c) Results from Experiment 1a, showing the number of items stored in memory (K) and the precision of the representations (inversely related to the standard deviation, SD). (d) Capacity results from Experiment 1b (SD could not be estimated reliably in this experiment given the granularity of the test display). Error bars in all data figures represent within-subjects 95% confidence intervals (Cousineau, 2007).
Figure 2
Figure 2
Capacity (K) and standard deviation (SD) results from Experiment 2 (a), Experiment 3 (b), Experiment 4a (c), and Experiment 4b (d).
See this image and copyright information in PMC

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