ABSTRACT
In the first century of the systematic study of psychology, roughly 1875 to 1975, there was clear agreement on the nature of infants. William James thought they inhabited a state of confusion, Jean Piaget portrayed them as having only simple sensory and motor skills without the ability for abstract internal representation, and Freudian theorists spoke of a state of primary narcissism and lack of differentiation between the self and the world. However, the next quarter century of research has produced a remarkable change in this consensus. Finding after finding has emerged pointing to infant capability and competence. Infants have been argued to be capable of imitation of other people at birth (e.g., Meltzoff & Moore, 1977), to have a concept of a permanent object (e.g., Baillargeon, 1987; Baillargeon & DeVos, 1991), to be endowed with core principles of physical knowledge (e.g., Spelke, Breinlinger, Macomber, & Jacobson, 1992), to engage in causal reasoning (e.g. Leslie & Keeble, 1987), and to have mathematical ability that includes not only a cross-modal concept of number (e.g., Starkey, Spelke, & Gelman, 1983, 1990) but also the competence to add and subtract (Wynn, 1992, 1995).
