Examining the relationship between degree of handedness and degree of cerebral lateralization for processing facial emotion.

This paper examines the relationship between degree of handedness and degree of cerebral lateralization on a task of processing positive facial emotion in right-handed individuals. Three hundred and thirteen right-handed participants (157 women) were given two behavioral tests of lateralization: a handedness questionnaire and a chimeric faces test. Two further handedness measures were taken: familial left-handedness and writing posture. Regression analysis showed that both degree of handedness and sex were predictive of degree of lateralization. Individuals who were strongly right-handed were also more strongly lateralized to the right hemisphere for the task. Men were more strongly lateralized than women. Data were reanalyzed for men and women separately. The relationship between handedness and lateralization remained for men only. Neither familial left-handedness nor writing posture were associated with cerebral lateralization for men or women. The results suggest a positive relationship between degree of handedness and degree of cerebral lateralization, and further that there is a sex difference in this relationship.