Dr. Henri Cohen's research interests focus on speech and language development and neurological disorders, learning and emotion in Parkinson's disease, complexity and learning, skill acquisition and interference, and origin of language. He is Professor of Psychology (ret.) at Universite du Quebec a Montreal, and visiting scholar, at Pontificia Universidad Catolica de Chile, Universidad de la Frontera, Chile. He has published over 100 peer-reviewed articles, and edited two books (with Elsevier) on cognition and consciousness, and on categorization, and a book on the origins of language (Benjamins). He is the current editor of Brain and Cognition (Elsevier), and past editor of Journal of Neurolinguistics (Elsevier). Department of Linguistics, University of Quebec, Montreal, Canada. Dr. Lefebvre studies: linguistic theory, syntactic category theory; cognitive processes involved in the formation of new languages; languages in contact, French, Quechua, Creole Haitian, Fon, and other African languages.