Suggests that in learning and development, the process of comparison can act as a bridge between similarity-based and rule-based processing. A structure-sensitive comparison process, triggered by experiential or symbolic juxtapositions can: (1) facilitate understanding of structural commonalities and the abstraction of rules; and (2) facilitate…

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)