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Gi-Yeul Bae, Colin Wilson, Jonathan Flombaum; Variability in color working memory precision reflects inherent stimulus properties. Journal of Vision 2013;13(9):461. doi: https://doi.org/10.1167/13.9.461.
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© ARVO (1962-2015); The Authors (2016-present)
State of the art visual working memory models suggest that resources are not only continuous, but also variable across items and trials. The cause of trial-to-trial variability remains unknown, with several possibilities proposed (e.g., doubly stochastic neural representation). One important possibility is that variation is due to the particular stimulus values presented in a trial. To explore this possibility, Experiment 1 used delayed estimation for color, testing participants at a memory load of one, probing each of 180 colors ten times. We found clear differences among these colors in average recall precision. Experiment 2 replicated a study by van de Berg et al. (2012), and fit their variable-precision model to the results. We averaged the model’s precision estimates for each color, and correlated these averages with the values obtained in Experiment 1. The correlation was highly significant, both overall and for each memory load, suggesting that differences among stimulus values account for a large proportion of the trial-to-trial variance. Experiment 3 investigated one reason why responses for certain colors might be more precise than for others. Participants were asked to identify the most prototypical example of each of seven colors by marking a color wheel. The least frequent selections served as good proxies for color category boundaries. We averaged the trial-to-trial variance estimates within each category for Experiment 1; these estimates correlated significantly with estimates derived in the same way for each color category at each memory load in Experiment 2. These results again suggest that trial variability is stimulus driven, perhaps reflecting categorical effects in color perception. This has important implications for modeling visual working memory, primarily, via the opportunity to account for trial variability with independent estimates of stimulus perception. We discuss a number of possible models employing such an approach.
Meeting abstract presented at VSS 2013
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