Recent studies have found that infants show relational learning in the first year. Like older children, they can abstract relations such as "same" or "different" across a series of exemplars. For older children, language has a major impact on relational learning: labeling a shared relation facilitates learning, while labeling…

Infants have shown variable success in quantity comparison tasks, with infants of a given age sometimes successfully discriminating numerical differences at a 2:3 ratio but requiring 1:2 and even 1:4 ratios of change at other times. The current explanations for these variable results include the two-systems proposal--a theoretical framework that…