Infants make quantity discriminations for substances.

Infants can track small groups of solid objects, and infants can respond when these quantities change. But earlier work is equivocal about whether infants can track continuous substances, such as piles of sand. Experiment 1 (N = 88) used a habituation paradigm to show infants can register changes in the size of piles of sand that they see poured from a container when there is a 1-to-4 ratio. Experiment 2 (N = 82) tested whether infants could discriminate a 1-to-2 ratio. The results demonstrate that females could discriminate the difference but males could not. These findings constitute the youngest evidence of successful quantity discriminations for a noncohesive substance and begin to characterize the nature of the representation for noncohesive entities.