Preschool Children's Mapping of Number Words to Nonsymbolic Numerosities

Abstract

Five-year-old children categorized as skilled versus unskilled counters were given verbal estimation and number word comprehension tasks with numerosities 20 - 120. Skilled counters showed a linear relation be- tween number words and nonsymbolic numerosities. Unskilled counters showed the same linear relation for smaller numbers to which they could count, but not for larger number words. Further tasks indicated that unskilled counters failed even to correctly order large number words differing by a 2 : 1 ratio, whereas they performed well on this task with smaller numbers, and performed well on a nonsymbolic ordering task with the same numerosities. These findings provide evidence that large, approximate numerosity representations be- come linked to number words around the time that children learn to count to those words reliably. Although infants represent and discriminate large numerosities (Lipton & Spelke, 2003; Xu & Spelke, 2000) and adults draw on large-number representa- tions when they perform symbolic arithmetic (De- haene, 1997; Gallistel & Gelman, 2000), it is not known whether preschool children use these non- verbal representations of number to master the symbolic number system. The present experiment investigates whether children link number words to nonsymbolic representations of numerosity before, during, or after they have learned to count to large numbers reliably. Studies of human infants, adults, and animals provide evidence for a language-independent rep- resentation of approximate numerosity (Dehaene, 1997; Gallistel, 1990; Meck & Church, 1983). For ex- ample, human adults successfully compare sets of dots and sequences of tones when the items are too numerous and too briefly presented for verbal counting, with accuracy dependent upon the ratio of the two sets (Barth, Kanwisher, & Spelke, 2003; Van Oeffelen & Vos, 1982). Moreover, adults prevented from counting are able to press a key a specified number of times, with scalar variability in their re- sponses proportional to numerosity (Whalen, Gal- listel, & Gelman, 1999). These findings provide evidence for a language-independent system for representing numerosity with a Weber ratio limit as