title: Number skills are maintained in healthy ageing.
abstract: Numerical skills have been extensively studied in terms of their development and pathological decline, but whether they change in healthy ageing is not well known. Longer exposure to numbers and quantity-related problems may progressively refine numerical skills, similar to what happens to other cognitive abilities like verbal memory. Alternatively, number skills may be sensitive to ageing, reflecting either a decline of number processing itself or of more auxiliary cognitive abilities that are involved in number tasks. To distinguish between these possibilities we tested 30 older and 30 younger participants on an established numerosity discrimination task requiring to judge which of two sets of items is more numerous, and on arithmetical tasks. Older participants were remarkably accurate in performing arithmetical tasks although their numerosity discrimination (also known as 'number acuity') was impaired. Further analyses indicate that this impairment was limited to numerosity trials requiring inhibiting information incongruent to numerosity (e.g., fewer but larger items), and that this also correlated with poor inhibitory processes measured by standard tests. Therefore, rather than a numerical impairment, poor numerosity discrimination is likely to reflect elderly's impoverished inhibitory processes. This conclusion is supported by simulations with a recent neuro-computational model of numerosity perception, where only the specific degradation of inhibitory processes produced a pattern that closely resembled older participants' performance. Numeracy seems therefore resilient to ageing but it is influenced by the decline of inhibitory processes supporting number performance, consistent with the 'Inhibitory Deficit' Theory.
authors.affiliation: UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK; Goldsmiths College, University of London, New Cross London, SE14 6NW, UK. Electronic address: m.cappelletti@ucl.ac.uk.
authors.forename: Marinella
authors.initials: M
authors.lastname: Cappelletti
authors.affiliation: Department of Cognitive and Education Science, University of Trento, via Tartarotti 7, Rovereto, Trento, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Didino
authors.affiliation: Department of General Psychology, University of Padova, via Venezia 8, 35131 Padova, Italy; Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy.
authors.forename: Ivilin
authors.initials: I
authors.lastname: Stoianov
authors.affiliation: Department of General Psychology, University of Padova, via Venezia 8, 35131 Padova, Italy; IRCCS San Camillo Hospital, Venice-Lido, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Zorzi
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000523:psychology*; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D011340:Problem Solving; D055815:Young Adult
keywords: Ageing; Computational modelling; Number acuity; Numerical cognition; Numerosity perception