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Giyeon Kim, Soohyun Cho, Joo-Seok Hyun; Individual differences in visual working memory capacity and search efficiency may predict distinct strategic processes for dot arrays by numerosity comparison sensitivity. Journal of Vision 2014;14(10):548. doi: https://doi.org/10.1167/14.10.548.
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© ARVO (1962-2015); The Authors (2016-present)
Numerosity comparison, the ability to compare quantities of two arrays of elements, is assumed to be as important to human mathematical ability as attention and working memory presumably are important. Accordingly, we attempted to explore the relationship of an individual's sensitivity to numerosity differences with their visual working memory (VWM) capacity and visual search efficiency. First, we measured the participant's VWM capacity using a color-change detection task (i.e., Cowan's K), and their search efficiencies (i.e., search slope). We then measured their numerosity comparison sensitivities in several tasks, that required comparing the quantities of two sequential (200ms each) or bilateral arrays (200ms). The dots were places either at identical locations (i.e., fixed-position) or random (i.e., scrambled-position) across the arrays, while the ratio for their quantities varied across trials. Each participant's comparison sensitivity(termed alpha [α]) for numerosity was defined as a 75%-accuracy threshold on a modeled logistic function. This function demonstrated a sigmoidal pattern of accuracies along the incremental quantity difference between the arrays, such that a lower alpha indicated higher sensitivity. The analyses for the sequential array trials found a negative correlation between Cowan's Ks and alphas in the fixed-position condition, and a positive correlation between search slopes and alphas in the scrambled-position condition. These results indicated that the participants used a strategy to exploit VWM capacity only if they were able to store the array as a global image, while they used a strategy to exploit a rapid shift of attention if they were unable to. However the analyses for the bilateral array trials found no correlations, indicating neither the strategy was possible due to the doubled array size and the brief exposure duration. These suggest that an individual's numerosity comparison sensitivity can be predicted by his or her VWM capacity and search efficiency.
Meeting abstract presented at VSS 2014
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