Preschoolers' magnitude comparisons are mediated by a preverbal analog mechanism.

We report a study of 3- to 5-year-olds who performed a magnitude-comparison task. Stimuli were a series of pairs of arrays that sometimes differed in numerosity, and the children were asked to point to the more numerous array in each pair. The proportion of accurate responses was above chance for all age groups. However, error patterns were consistent with analog models of magnitude representation. Errors varied systematically with the ratio of stimulus pairs. Items with a 2:3 ratio were harder than items with a 1:2 ratio. Performance on posttests of verbal counting ability was variable, but did not predict performance on the numerical discrimination task. We argue that neither verbal counting nor nonnumerical perceptual strategies can explain these results. This study supports the hypothesis that adults and children share preverbal, analog representations of magnitude.