The emotional basis of linguistic and nonlinguistic intonation: implications for hemispheric specialization

Clinical and experimental studies suggest that the right cerebral hemisphere is dominant for intonation or the "melody of language." In light of this brain-behavior correlation, an assessment of intonation is a useful adjunct of the linguistic, cognitive, and neurological evaluation of patients with brain damage. However, the neural basis of intonation is controversial. This article examines 1 of the unresolved issues--the hypothesis that emotional versus linguistic categories of intonation are lateralized to the opposite hemispheres. A review of linguistic and neurobehavioral evidence fails to support the claim that intonation is divided into dichotomous categories. Linguistic analysis suggests that even intonation patterns traditionally described as nonemotional have their underpinnings in the speaker's emotions. Similarly, studies of adults and children with brain damage indicate that intonation patterns described as either linguistic or emotional are mediated by right-hemisphere substrate specialized for emotional experience. The cross-disciplinary findings support a general right-hemisphere hypothesis that unifies linguistic and emotional uses of intonation in children and adults. Implications of the hypothesis are discussed in relation to the diagnosis of developmental disorders, with special attention to the problem of identifying language impairment in infants and toddlers.