title: Operational momentum in large-number addition and subtraction by 9-month-olds.
abstract: Recent studies on nonsymbolic arithmetic have illustrated that under conditions that prevent exact calculation, adults display a systematic tendency to overestimate the answers to addition problems and underestimate the answers to subtraction problems. It has been suggested that this operational momentum results from exposure to a culture-specific practice of representing numbers spatially; alternatively, the mind may represent numbers in spatial terms from early in development. In the current study, we asked whether operational momentum is present during infancy, prior to exposure to culture-specific representations of numbers. Infants (9-month-olds) were shown videos of events involving the addition or subtraction of objects with three different types of outcomes: numerically correct, too large, and too small. Infants looked significantly longer only at those incorrect outcomes that violated the momentum of the arithmetic operation (i.e., at too-large outcomes in subtraction events and too-small outcomes in addition events). The presence of operational momentum during infancy indicates developmental continuity in the underlying mechanisms used when operating over numerical representations.
authors.affiliation: Department of Psychology, Harvard University, Cambridge, MA 02138, USA. mccrink@wjh.harvard.edu
authors.forename: Koleen
authors.initials: K
authors.lastname: McCrink
authors.forename: Karen
authors.initials: K
authors.lastname: Wynn
mesh_terms: D002657:Child Development; D003071:Cognition; D003210:Concept Formation; D004193:Discrimination Learning; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D007223:Infant; D008297:Male; D008433:Mathematics; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D013561:Symbolism; D013647:Task Performance and Analysis