A compilation of the proceedings of a conference held to honor Alvin M. Liberman for his outstanding contributions to research in speech perception, this volume deals with two closely related and controversial proposals for which Liberman and his colleagues at Haskins Laboratories have argued forcefully over the past 35 years. The first is that articulatory gestures are the units not only of speech production but also of speech perception; the second is that speech production and perception are not cognitive processes, but rather functions of a special mechanism. This book explores the implications of these proposals not only for speech production and speech perception, but for the neurophysiology of language, language acquisition, higher-level linguistic processing, the visual perception of phonetic gestures, the production and perception of sign language, the reading process, and learning to read. The contributors to this volume include linguists, psycholinguists, speech scientists, neurophysiologists, and ethologists. Liberman himself responds in the final chapter.