title: Spontaneous perception of numerosity in humans.
abstract: Humans, including infants, and many other species have a capacity for rapid, nonverbal estimation of numerosity. However, the mechanisms for number perception are still not clear; some maintain that the system calculates numerosity via density estimates-similar to those involved in texture-while others maintain that more direct, dedicated mechanisms are involved. Here we show that provided that items are not packed too densely, human subjects are far more sensitive to numerosity than to either density or area. In a two-dimensional space spanning density, area and numerosity, subjects spontaneously react with far greater sensitivity to changes in numerosity, than either area or density. Even in tasks where they were explicitly instructed to make density or area judgments, they responded spontaneously to number. We conclude, that humans extract number information, directly and spontaneously, via dedicated mechanisms.
authors.affiliation: Institute of Neuroscience, National Research Council, 56124 Pisa, Italy.
authors.forename: Guido Marco
authors.identifier: 0000-0002-3303-0420
authors.initials: GM
authors.lastname: Cicchini
authors.affiliation: Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, 50121 Florence, Italy.|Department of Developmental Neuroscience, Stella Maris Scientific Institute, 56018 Pisa, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Anobile
authors.affiliation: Institute of Neuroscience, National Research Council, 56124 Pisa, Italy.|Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, 50121 Florence, Italy.|School of Psychology, University of Western Australia, 6009 WA Perth, Australia.
authors.forename: David C
authors.initials: DC
authors.lastname: Burr
mesh_terms: D000328:Adult; D003463:Cues; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D007600:Judgment; D008297:Male; D055641:Mathematical Concepts; D010364:Pattern Recognition, Visual; D014796:Visual Perception / Q000502:physiology*