title: Developmental trajectory of number acuity reveals a severe impairment in developmental dyscalculia.
abstract: Developmental dyscalculia is a learning disability that affects the acquisition of knowledge about numbers and arithmetic. It is widely assumed that numeracy is rooted on the "number sense", a core ability to grasp numerical quantities that humans share with other animals and deploy spontaneously at birth. To probe the links between number sense and dyscalculia, we used a psychophysical test to measure the Weber fraction for the numerosity of sets of dots, hereafter called number acuity. We show that number acuity improves with age in typically developing children. In dyscalculics, numerical acuity is severely impaired, with 10-year-old dyscalculics scoring at the level of 5-year-old normally developing children. Moreover, the severity of the number acuity impairment predicts the defective performance on tasks involving the manipulation of symbolic numbers. These results establish for the first time a clear association between dyscalculia and impaired "number sense", and they may open up new horizons for the early diagnosis and rehabilitation of mathematical learning deficits.
authors.affiliation: Inserm-CEA Cognitive Neuroimaging Unit, Gif-sur-Yvette, France. manuela.piazza@gmail.com <manuela.piazza@gmail.com>
authors.forename: Manuela
authors.initials: M
authors.lastname: Piazza
authors.forename: Andrea
authors.initials: A
authors.lastname: Facoetti
authors.forename: Anna Noemi
authors.initials: AN
authors.lastname: Trussardi
authors.forename: Ilaria
authors.initials: I
authors.lastname: Berteletti
authors.forename: Stefano
authors.initials: S
authors.lastname: Conte
authors.forename: Daniela
authors.initials: D
authors.lastname: Lucangeli
authors.forename: Stanislas
authors.initials: S
authors.lastname: Dehaene
authors.forename: Marco
authors.initials: M
authors.lastname: Zorzi
mesh_terms: D000328:Adult; D000375:Aging / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D007859:Learning Disabilities / Q000523:psychology*; D008297:Male; D008433:Mathematics; D009483:Neuropsychological Tests; D055815:Young Adult