Origins of number sense. Large-number discrimination in human infants.
Four experiments investigated infants' sensitivity to large, approximate numerosities in auditory sequences. Prior studies provided evidence that 6-month-old infants discriminate large numerosities that differ by a ratio of 2.0, but not 1.5, when presented with arrays of visual forms in which many continuous variables are controlled. The present studies used a head-turn preference procedure to test for infants' numerosity discrimination with auditory sequences designed to control for element duration, sequence duration, interelement interval, and amount of acoustic energy. Six-month-old infants discriminated 16 from 8 sounds but failed to discriminate 12 from 8 sounds, providing evidence that the same 2.0 ratio limits numerosity discrimination in auditory-temporal sequences and visual-spatial arrays. Nine-month-old infants, in contrast, successfully discriminated 12 from 8 sounds, but not 10 from 8 sounds, providing evidence that numerosity discrimination increases in precision over development, prior to the emergence of language or symbolic counting.
Lipton
Jennifer S
JS
Massachusetts Institute of Technology, MA, USA. lipton@wjh.harvard.edu
Spelke
Elizabeth S
ES
D000367:Age Factors; D001288:Attention; D001307:Auditory Perception; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D007223:Infant; D007804:Language Development; D008297:Male; D008433:Mathematics; D011340:Problem Solving; D002666:Psychology, Child; D012691:Serial Learning