Examination of Complementarity in Speech and Emotional Vocalization Perception

Abstract

Lateralization of cognitive functioning is a well-established principle of cerebral organization. The left and right hemispheres are known to play distinct and complementary roles in the processing of information. What is still unclear is whether these asymmetrically lateralized functions have a common or distinct developmental origin; are left and right processes lateralized through causal influences, or is the laterality of each function independently influenced? Left- and right-lateralized functions are commonly assessed in isolation, with little attention to the relationship in the degree and direction of lateralization within individuals. This relationship between left-hemisphere processing of speech sounds and right-hemisphere processing of emotional vocalizations was examined using dichotic listening tasks. An overall complementary pattern of lateralization was observed across participants, but no significant relationship was found for degree of lateralization of speech and emotional vocalization processing within individuals. These results support the view that functions in the left and right hemispheres are independently lateralized.