Brain specialization for melodic processing: A developmental comparison of auditory and visual patterns

Converging evidence from research on visual and auditory pattern perception suggests commonalities between the two modalities in terms of hemispheric specialization and development. A right hemisphere advantage has been found in adults for configural aspects of visual and auditory stimuli, and a left hemisphere advantage for featural aspects of visual and auditory stimuli, suggesting a perceptual organization for parts and wholes that is not modality specific. Developmental changes in brain mediation for features and configurations may be parallel for vision and audition. During adolescence, the perception of configurations in both melody recognition and face recognition appear to be disrupted. This thesis investigated hemispheric specialization for features and configurations across development, drawing on tasks derived from studies of music perception, face perception, and visual global and local processing. Nine- to fourteen-year-olds and adults performed auditory and visual tasks that included configural and featural components. Specifically, the advantage for configural stimuli with initial right hemisphere presentation commonly found for adults was expected to be weaker during early adolescence than for younger children and adults. In general, results indicated a weaker right hemisphere advantage for configural aspects of the tasks for children, relative to adults, providing evidence for a relatively late development of the right hemisphere, or a reorganization in the manner in which the right hemisphere mediates configurations. Conversely, both children and adults performed better on featural aspects of the tasks with initial left hemisphere presentation. Both the left hemisphere advantage for features and the right hemisphere advantage for configurations were weaker in children aged 11 to 13 than in adults or in younger children. Thus, the discontinuity found during early adolescence is not specific to the right hemisphere, but to the strength of lateralization in both the left and right hemispheres. There was a concordance in the timing of this change for the auditory and visual tasks. This discontinuity could signify a developmental change in the degree of independence between the two hemispheres that affects the relative strength of configural versus featural information.