Addresses two questions that may be unique to perceptual learning: What are the circumstances that produce learning? and What is the content of learning? Suggests a critical principle for each question. Provides a discussion of perceptual learning theory, how learning occurs, and what gets learned. Includes a 121-item bibliography. (DR)

Piaget's theory of space perception is presented in the format of a hypothetico-deductive system. Eleven hypotheses regarding infants' space perception are defined, and Piaget's evidence for each is summarized. Presuppositions underlying the arguments are explicated. Critical notes are inserted and general conclusions are briefly discussed.…