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Dryad

Feature selective adaptation of numerosity perception

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Jan 02, 2025 version files 21.66 KB

Abstract

Perceptual adaptation has been widely used to infer the existence of numerosity detectors, enabling animals to quickly estimate the number of objects in a scene. Here we investigated, in humans, whether numerosity adaptation is influenced by stimuli features changes as previous research suggested that adaptation is more pronounced when adapting and test stimuli share the same color. We tested whether such adaptation reduction is due to a novelty effect (due to changing stimulus features) or changes of stimuli identity. Numerosity adaptation was measured for stimuli matched or unmatched for low-level (color, luminance, shape, motion) or high-level (letters' identity, face emotions) features. Robust numerosity adaptation occurred in all conditions but it was reduced when adapting and test stimuli differed for color, luminance, and shape. However, no reduction was observed between moving and still stimuli, a readable change that did not affect item’s identity. Similarly, changes in letters' spatial rotations or face features did not affect adaptation magnitude. Image dissimilarity, quantified by Gabor filters modeling V1 predicted numerosity adaptation strength. These findings suggest that low-level feature changes, rather than novelty per sè, affect adaptation strength with numerosity mechanisms operating on categorized items in addition to the total quantity of the set.