Hemispheric functionality patterns between dextrals and sinistrals in tactile-visual tasks at lower or higher level of mental processes.

Two different patterns of unilateral tactile-visual recognition tasks with random shapes were administered to 64 subjects, 32 right-handed (16 males, 16 females) and 32 left-handed (16 males, 16 females). The main effects were found in the over-all performance: dextral subjects performed better than sinistral subjects; males performed better than females. On the task at a lower level of mental process dextral subjects performed better over-all than the sinistral subjects; however, neither group showed superiority of one hand over the other. On the task at a higher level of mental process performance of sinistral subjects improved to a level equivalent to that of the dextral subjects. Dextral subjects tended to perform better with their left hands, whereas the sinistral subjects scored equally with both hands. The findings are discussed in terms of quantitative and qualitative differences in patterns of hemispheric functionality between dextral and sinistral subjects, and the more specific cerebral activation for tasks at a higher level of mental process is hypothesized.