Influence of sex and handedness on hemispheric functioning

Forty normal adult volunteers comprising an equal number of right- and left-handed males and females solved simple multiplication problems presented visually to one cerebral hemisphere while various competing stimuli were simultaneously presented to the other hemisphere. The contribution of sex of subject, handedness, hemisphere of presentation and the nature of the competing stimulus in relation to task performance was examined. Each of these variables was significantly associated with correct responses and errors, with few statistically significant interactions. Females and dextrals made more correct responses than males or sinistrals. Type of error depended upon which hemisphere received the problem, with the right hemisphere yielding more errors of commission and the left more errors of omission. Simultaneously presented identical or different arithmetic problems resulted in the most errors compared to the other competing stimuli.