Reut Peled¹ (), Roy Luria^1,2; ¹The school of Psychological Sciences, ²The Sagol School of Neuroscience

Considering working memory capacity limitations, representing all relevant data simultaneously is unlikely; What remains unclear is why some items are better remembered than others when all data is equally relevant. While trying to answer this question, the literature has identified a pattern named the mixed-category benefit in which performance is enhanced when presenting stimuli from different categories as compared to presenting a similar number of items that all belong to just one category. Moreover, previous studies revealed an asymmetry in performance while mixing various categories, suggesting that not all categories benefit evenly from being mixed. In a series of 3 change-detection experiments, the present study sought to extend the scope of knowledge regarding the mixed-category effect, specifically investigating the role of low-level perceptual similarities. By creating perceptual similarities between two of three distinct categories, Experiment 1 (N=27) revealed a significantly stronger mixed-category advantage for combined categories that did not share low-level similarities. To further examine this effect, Experiment 2 (N=27) used novel and familiar items that share perceptual similarities but differ in their familiarity levels; this time, instead of a mixed-category benefit, a performance cost emerged for the novel items while paired with the familiar stimuli holding similar features. Consequently, in Experiment 3 (N=29), we tried to explain the novelty-familiarity trade-off effect in terms of stimuli complexity consuming extended encoding time. Our findings suggest that different categories sharing low-level similarities can explain a portion of the asymmetric enhancement in performance in the mixed-category effect, regardless of stimuli complexity levels.