Roberto Arrighi, Paula Maldonado, Marco Cicchini, David Burr
Numerosity adaptation: changes in sensory processes or in decision making?
European Workshop on Cognitive Neuropsychology EWCN 2020
Introduction : Humans and other animals can make rapid but approximate estimates of the numerosity of items in a scene, an ability often termed the number sense. Numerosity perception, like other senses, is susceptible to sensory adaptation: after an exposure to a patch containing many dots, subjects underestimate the numerosity of a second stimulus subsequently presented in the adapted region, with the opposite occurring for adaptation to small numerosities. Do these aftereffects arise from a change in the processing of sensory signals, or from a shift of criteria at the decisional stage? Methods : We addressed this question by investigating the effects of numerosity visual adaptation and motor adaptation in a 2AFC discrimination task on apparent numerosity (measured as point of subjective equality, or PSE), as well as on subjective confidence and reaction time. Results : Our results show that shifts in perceived numerosity after visual and motor adaptation are mirrored by shifts in both confidence and reaction time, with the maximum uncertainty and longest response time occurring at the point of subjective equality rather than at the point of physical equality. Discussion : Taken together these results are consistent with the hypothesis that numerosity adaptation aftereffects are perceptual in nature and not related to decisional processes. References : Morgan M. et al. Atten Percept Psychophys. (2012) 74(1):185-93. Abobile et al. eLife (2016) 5: e16161. Keywords : Numerical Cognition; normal population; group study; adults; not relevant; behavioural, behavioural.