Compared children's performance on initial-unknown and final-unknown problems involving the addition or subtraction of a single item. Found that although 4-year olds responded in a directionally appropriate way to the final-unknown problems but not to the corresponding initial-unknown ones, 5-year olds were able to respond appropriately to both.…

Two experiments examined children's early judgments about numerical relations. Found that children as young as three years old are already adept at reasoning about relations between sets, independently of their ability to form numerical representations. Results support the existence of protoquantitative schemas, or ways of thinking about relations…

Two experiments examined the development of children's understanding of part-whole relations. Found that five- and six-year olds evidenced understanding of part-whole relations, but four-year olds did not. Results support the conclusion that an understanding of the relationship between a superordinate set and the basic-level sets that comprise it…