ABSTRACT
The real challenge for developmental psychology is to explain how and why behaviors emerge. Suppose, for example, that you want to understand what causes an infant to look more at one stimulus than another, or how it is that infants develop language abilities so quickly. Perhaps you wish to know why infants appear to have sophisticated knowledge of hidden objects if tested visually but not if tested manually, or how they learn to organize the world into categories. There are many ways to tackle these questions. One long-standing approach has been to describe infant competence across different domains in great detail in the hopes that, by establishing the milestones of development, some kind of causal explanation will emerge from a synthesis of the data.
