Hemispheric lateralisation in a manual-verbal task combination: the role of modality and gender.

Differences in hemispheric lateralisation between males and females were tested using a manual-verbal task combination. The manual task was finger tapping and the verbal task required reciting words. Words were presented either visually or aurally in order to examine a possible role of modality of presentation on hemispheric lateralisation. The influence of the verbal task on motor task performance was evaluated by changes in the number of taps from single to dual-task condition. The influence of the motor task performance on the verbal task was examined by changes in the number of words recalled. Cognitive performance differences between males and females were also examined in a mental rotation task. The results showed a greater right finger (RH) tapping than left finger (LH) tapping interference, but only when the verbal task was presented in the visual mode. There was no difference in this pattern between males and females, both showing a greater RH tapping than LH tapping interference. The interference in finger tapping for both RH and LH was greater when the verbal task was presented aurally than when presented visually. Furthermore, females compared to males showed a greater interference in finger tapping when the verbal task was presented aurally than when presented visually. Later recall of verbal information was impaired equally by concurrent RH or LH tapping; however, later recall was better when the verbal task was presented visually than when presented aurally. No gender differences were found in delayed recall. Performance in the mental rotation task was better in males than in females. The data are discussed on the basis of theories of dual task interference and/or of brain asymmetry.