Book excerpt: The Emergence of Symbols: Cognition and Communication in Infancy provides information pertinent to the nature and origin of symbols, the interdependence of language and thought, and the parallels between phylogeny and ontogeny. This book clarifies some of the conceptual and methodological issues involved in the search for prerequisites to language. Organized into seven chapters, this book begins with an overview of the distinction between homology and analogy in the study of linguistic and nonlinguistic developments. This text then explains the conceptual and operational definitions for such controversial terms as intention, convention, and symbolic behavior. Other chapters consider the limits and advantages of the correlational method as applied in the research. This book discusses as well the structure and content of early symbol use, both in language and in play. The final chapter examines the processes that underlie imitation and tool use, as they contribute to the child's analysis of his culture. This book is a valuable resource for neural biologists, psychologists, and social scientists.