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Behavioral signatures of the rapid recruitment of long-term memory to overcome working memory capacity limits

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Abstract

Working- and long-term memory are often studied in isolation. To better understand the specific limitations of working memory, effort is made to reduce the potential influence of long-term memory on performance in working memory tasks (e.g., asking participants to remember artificial, abstract items rather than familiar real-world objects). However, in everyday life we use working- and long-term memory in tandem. Here, our goal was to characterize how long-term memory can be recruited to circumvent capacity limits in a typical visual working memory task (i.e., remembering colored squares). Prior work has shown that incidental repetitions of working memory arrays often do not improve visual working memory performance – even after dozens of incidental repetitions, working memory performance often shows no improvement for repeated arrays. Here, we used a whole-report working memory task with explicit rather than incidental repetitions of arrays. In contrast to prior work with incidental repetitions, in two behavioral experiments we found that explicit repetitions of arrays yielded robust improvement to working memory performance, even after a single repetition. Participants performed above chance at recognizing repeated arrays in a later long-term memory test, consistent with the idea that long-term memory was used to rapidly improve performance across array repetitions. Finally, we analyzed inter-item response times and we found a response time signature of chunk formation that only emerged after the array was repeated (inter-response time slowing after two to three items); thus, inter-item response times may be useful for examining the coordinated interaction of visual working and long-term memory in future work.

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Data availability

Raw data and code to reproduce analyses will be made available on the Open Science Framework upon publication (https://osf.io/dw7cp/).

Notes

  1. Although there is some debate as to how much a redundant verbal code can benefit visual working memory performance, prior work has shown that redundant verbal codes do not greatly boost performance in visual working memory tasks using abstract stimuli. For example, performance has been shown to be equivalent with and without articulatory suppression (Sense et al., 2017). However, emerging work is characterizing how semantically meaningful labels may boost performance by recruiting visual long-term memory (Forsberg et al., 2020; Overkott & Souza, 2021; Souza et al., 2021).

  2. In long-term memory search studies, the “memory set” refers to the group of items that the participant is trying to recall from memory.

  3. Note, here we have reworded McLean and Gregg’s (1967) framework to better reflect today’s vernacular. The original quote (reproduced in Cowan, 2001) from McLean and Gregg (1967) is: “(a) Some stimuli may already form a unit with which S is familiar. (b) External punctuation of the stimuli may serve to create groupings of the individual elements. (c) The S may monitor his own performance and impose structure by selective attention, rehearsal, or other means.”

  4. Greenhouse-Geisser corrected p-values are reported when the assumption of sphericity is violated.

  5. Note, a one-tailed t-test was chosen for this comparison, because we would not expect memory performance to be meaningfully below chance. All statistical tests are two-tailed unless otherwise noted.

  6. Note, an independent t-test including all conditions with enough trials in at least one of the two confidence bins yielded similar results (n = 43 high confidence; n = 48 low confidence), t(89) = 3.15, p = .002.

  7. Likewise, we again found a consistent result when we included all possible conditions with an independent t-test (n = 45 high confidence; n = 48 low confidence), t(91) = 2.46, p = .016.

  8. Here, we assessed participants’ self-estimates of performance after they had already completed the task (post-diction). Prior work on memory self-efficacy has shown that self-estimates made before ever experiencing a task (predictions) would be less strongly correlated with performance compared to post-dictions (Beaudoin & Desrichard, 2011; Hertzog et al., 1990, 1994; West et al., 1996).

  9. One additional participant was missing a response for the motivation item (N = 48 for this item).

  10. Note, d’ values are approximate. Values were extracted from Fig. S1 of the Supplementary Materials of Musfeld et al. (2023b) using WebPlotDigitizer (Rohatgi, 2022). Specifically, the authors reported the probability that the participant responded “old” for the critical Hebb array (hits) versus for a randomly generated “new” array (false alarms). We calculated d’ from these two values to make them comparable to how we quantified long-term memory performance.

  11. Although increased encoding time has not been shown to improve visual working memory performance, this contrasts with the verbal literature where encoding time has been shown to improve recall (e.g., Waugh, 1967).

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Acknowledgements

We thank Rebecca Kuang for assistance with data collection.

Funding

NSF SBE Postdoctoral Fellowship 2104630 to K.A. and grants ONR-N000142212123 and R01-MH087214 to E.V.

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KA: Conceptualization, methodology, validation, formal analysis, investigation, writing - original draft, writing - review and editing, visualization. CZ: Validation, writing - review and editing. EV: Funding acquisition, writing - review and editing.

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Correspondence to Kirsten C. S. Adam.

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Adam, K.C.S., Zhao, C. & Vogel, E.K. Behavioral signatures of the rapid recruitment of long-term memory to overcome working memory capacity limits. Mem Cogn (2024). https://doi.org/10.3758/s13421-024-01566-z

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  • DOI: https://doi.org/10.3758/s13421-024-01566-z

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