Temporal sequencing of verbal and nonverbal materials: the effect of laterality of lesion.

The effect of laterality of cerebral lesion on sequencing ability, which is an ability to process two or more stimulus events with respect to the order in which they occur, was examined. Patients with either left or right hemisphere lesions performed on verbal and nonverbal sequencing tasks. Left hemisphere lesioned patients were inferior to the right hemisphere lesioned patients on verbal sequencing tasks, while the right hemisphere lesioned patients were inferior to the left hemisphere lesioned patients on nonverbal sequencing tasks. Impaired performance of the right hemisphere lesioned patients on sequencing tasks raises questions with respect to the notion that sequencing per se is processed in the left hemisphere. Our results demonstrate that sequencing ability, as many other abilities, follows the rule of material-specific laterality of hemispheric asymmetry: the left hemisphere associated with verbal sequencing ability and the right hemisphere associated with nonverbal sequencing ability.