Book excerpt: Gestures are unique because they communicate an individual's moods and desires to the world but operate under different psychological and cognitive constraints than other actions. Thus, the connections between gesture and language - spoken and signed - pose some fascinating questions. How intimately are gesture and language connected? Did one evolve from the other? To what extent are they similarly processed in the brain? And in what ways are signed languages akin to spoken language and gestures? Gesture, Speech, and Sign examines these questions, bringing together an array of experts from all over the world to explore the origins, neurobiology, and uses of these three communication systems. Its discussion of how a greater understanding of the issues surrounding gesture and language can be used to improve human-computer interactions is an important and distinguishing feature of the book. Designed to appeal to a multi-disciplinary audience, Gesture, Speech, and Sign is perfect for advanced students and researchers in neuroscience, psychology, linguistics, and computer science as well as to those involved in deaf studies.