title: Does subitizing reflect numerical estimation?
abstract: Subitizing is the rapid and accurate enumeration of small sets (up to 3-4 items). Although subitizing has been studied extensively since its first description about 100 years ago, its underlying mechanisms remain debated. One hypothesis proposes that subitizing results from numerical estimation mechanisms that, according to Weber's law, operate with high precision for small numbers. Alternatively, subitizing might rely on a distinct process dedicated to small numerosities. In this study, we tested the hypothesis that there is a shared estimation system for small and large quantities in human adults, using a masked forced-choice paradigm in which participants named the numerosity of displays taken from sets matched for discrimination difficulty; one set ranged from 1 through 8 items, and the other ranged from 10 through 80 items. Results showed a clear violation of Weber's law (much higher precision over numerosities 1-4 than over numerosities 10-40), thus refuting the single-estimation-system hypothesis and supporting the notion of a dedicated mechanism for apprehending small numerosities.
authors.affiliation: INSERM, U562, Cognitive Neuroimaging Unit, Gif/Yvette, France. susannahrevkin@gmail.com
authors.forename: Susannah K
authors.initials: SK
authors.lastname: Revkin
authors.forename: Manuela
authors.initials: M
authors.lastname: Piazza
authors.forename: Véronique
authors.initials: V
authors.lastname: Izard
authors.forename: Laurent
authors.initials: L
authors.lastname: Cohen
authors.forename: Stanislas
authors.initials: S
authors.lastname: Dehaene
mesh_terms: D000293:Adolescent; D000328:Adult; D002755:Choice Behavior / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D010470:Perceptual Masking / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011340:Problem Solving / Q000502:physiology*; D011582:Psychological Theory; D011930:Reaction Time / Q000502:physiology; D013647:Task Performance and Analysis; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology*