The reliability and stability of visual working memory capacity
Because of the central role of working memory capacity in cognition, many studies have used short measures of working memory capacity to examine its relationship to other domains. Here, we measured the reliability and stability of visual working memory capacity, measured using a single-probe change detection task. In Experiment 1, the participants (N = 135) completed a large number of trials of a change detection task (540 in total, 180 each of set sizes 4, 6, and 8). With large numbers of both trials and participants, reliability estimates were high (α > .9). We then used an iterative down-sampling procedure to create a look-up table for expected reliability in experiments with small sample sizes. In Experiment 2, the participants (N = 79) completed 31 sessions of single-probe change detection. The first 30 sessions took place over 30 consecutive days, and the last session took place 30 days later. This unprecedented number of sessions allowed us to examine the effects of practice on stability and internal reliability. Even after much practice, individual differences were stable over time (average between-session r = .76).
KeywordsVisual working memory Reliability Change detection
Z.X. and E.V. designed the experiments; Z.X. and X.F. collected data. K.A. performed the analyses and drafted the manuscript, and K.A., Z.X., and E.V. revised the manuscript.
Research was supported by the Project of Humanities and Social Sciences, Ministry of Education, China (15YJA190008), the Fundamental Research Funds for the Central Universities (SWU1309117), NIH Grant 2R01 MH087214-06A1, and Office of Naval Research Grant N00014-12-1-0972. Datasets for all experiments are available online on Open Science Framework at https://osf.io/g7txf/.
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Conflicts of interest
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