Gesture, brain, and language

People gesture when they speak. For the past 20 years, researchers have investigated the behavioral roles that these co-speech gestures play in language processing. This special issue represents the next phase of research on this topic by presenting eight papers that explore the neural links between gesture and speech during language production and comprehension. Since the publication in 1992 of David McNeill's book Hand and Mind—a work that clearly situated the study of co-speech gesture into the domain of cognition and lan-guage—there has been growing interest in gesture across several disciplines, from cognitive science to psycholinguis-tics and from developmental psychology to evolutionary anthropology. One of the consistent messages from this varied research is that speech and gesture are deeply connected systems of communication. Specifically, researchers have demonstrated that gestures: (1) are semantically and temporally linked to the content of the ongoing speech stream, (2) have similar communicative functions as speech, and (3) develop closely with language acquisition in children. Furthermore , in terms of comprehension, listeners/viewers seem to pick up meaning of gesture, and do so in ways that are inte-This interest in discovering links between speech and gesture gained new momentum with Rizzolatti and Arbib's seminal discovery of ''mirror neurons'' These neurons discharge both when a monkey executes a specific manual action and when he observes another primate executing the same action. Since their discovery, several papers have investigated whether the human brain, specifically Broca's area, also has similar ''mirror proper-ties'' and furthermore whether this remarkable example of evolutionary conservation might reflect a neural relationship between language and action systems in humans The possible evolutionary link between action and language has fueled recent research on the neural processing of speech and gesture in humans. Indeed, gestures are a special type of action—they naturally and ubiquitously accompany spoken language, and certain types of gesture never occur in isolation from speech (McNeill, 1992). Although separate lines of research in the domains of language and action suggest that the two systems share overlapping brain areas/functions (e. there is a surprising paucity of research directly and empirically investigating language and action together. If researchers want to better understand this neural relationship in the human brain, a prime place to look is co-speech gesture. Previous studies investigating the neural links between speech and gestures have focused on clinical populations, such as aphasics (see Rose, 2006, for a review) and split-ever, there has been conflicting …