You Cannot "Count" How Many Items People Remember in Visual Working Memory: The Importance of Signal Detection-Based Measures for Understanding Change Detection Performance
Change detection tasks are commonly used to measure and understand the nature of visual working memory capacity. Across three experiments, we examine whether the nature of the memory signals used to perform change detection are continuous or all-or-none and consider the implications for proper measu...
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Veröffentlicht in: | Journal of experimental psychology. Human perception and performance 2022-12, Vol.48 (12), p.1390-1409 |
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Sprache: | eng |
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Zusammenfassung: | Change detection tasks are commonly used to measure and understand the nature of visual working memory capacity. Across three experiments, we examine whether the nature of the memory signals used to perform change detection are continuous or all-or-none and consider the implications for proper measurement of performance. In Experiment 1, we find evidence from confidence reports that visual working memory is continuous in strength, with strong support for an equal variance signal detection model with no guesses or lapses. Experiments 2 and 3 test an implication of this, which is that K should confound response criteria and memory. We found K values increased by roughly 30% when criteria are shifted despite no change in the underlying memory signals. Overall, our data call into question a large body of work using threshold measures, like K, to analyze change detection data. This metric confounds response bias with memory performance and is inconsistent with the vast majority of visual working memory models, which propose variations in precision or strength are present in working memory. Instead, our data indicate an equal variance signal detection model (and thus, d')-without need for lapses or guesses-is sufficient to explain change detection performance.
Public Significance Statement
Visual working memory is an essential, capacity-limited system that has been linked to many cognitive abilities such as fluid intelligence and reading comprehension. Because of its importance, researchers need valid measures of its capacity that separate true differences in memory performance from other factors, like participants' response strategies. Here we show that the most common measure of visual working memory capacity does not accurately separate response strategy from memory performance. We demonstrate this by showing we can artificially inflate estimates of capacity using this metric with a simple instruction change, which should have no effect on memory. We show an alternative metric is more accurate and suggest it should be used instead. These findings call into question research that has used this flawed metric to make connections between working memory capacity and other cognitive functions. |
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ISSN: | 0096-1523 1939-1277 |
DOI: | 10.1037/xhp0001055 |