title: Adaptation to number operates on perceived rather than physical numerosity.
abstract: Humans share with many animals a number sense, the ability to estimate rapidly the approximate number of items in a scene. Recent work has shown that like many other perceptual attributes, numerosity is susceptible to adaptation. It is not clear, however, whether adaptation works directly on mechanisms selective to numerosity, or via related mechanisms, such as those tuned to texture density. To disentangle this issue we measured adaptation of numerosity of 10 pairs of connected dots, as connecting dots makes them appear to be less numerous than unconnected dots. Adaptation to a 20-dot pattern (same number of dots as the test) caused robust reduction in apparent numerosity of the connected-dot pattern, but not of the unconnected dot-pattern. This suggests that adaptation to numerosity, at least for relatively sparse dot-pattern, occurs at neural levels encoding perceived numerosity, rather than at lower levels responding to the number of elements in the scene.
authors.affiliation: Department of Neuroscience, Psychology, Pharmacology and Child Health (NEUROFARBA), University of Florence, Via di San Salvi 12, 50139 Firenze, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Fornaciai
authors.affiliation: Institute of Neuroscience, National Research Council (CNR), Viale Moruzzi 1, Pisa 56124, Italy.
authors.forename: G M
authors.initials: GM
authors.lastname: Cicchini
authors.affiliation: Department of Neuroscience, Psychology, Pharmacology and Child Health (NEUROFARBA), University of Florence, Via di San Salvi 12, 50139 Firenze, Italy; Institute of Neuroscience, National Research Council (CNR), Viale Moruzzi 1, Pisa 56124, Italy. Electronic address: dave@in.cnr.it.
authors.forename: D C
authors.initials: DC
authors.lastname: Burr
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D006801:Humans; D008433:Mathematics / Q000379:methods; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011897:Random Allocation
keywords: Adaptation; Number; Numerosity discrimination; Segmentation; Vision