Sex differences in left–right confusion depend on hemispheric asymmetry

Numerous studies have reported that women believe they are more susceptible to left–right confusion than men. Indeed, some studies have also found sex differences in behavioural tasks. It has been suggested that women have more difficulties with left–right discrimination, because they are less lateralised than men and a lower degree of lateralisation might lead to more left–right confusion (LRC). However, those studies reporting more left–right confusion for women have been criticised because the tasks that have been used involved mental rotation, a spatial ability in which men typically excel. In the present study, 34 right-handed women and 31 right-handed men completed two behavioural left–right discrimination tasks, in which mental rotation was either experimentally controlled for or was not needed. To measure the degree of hemispheric asymmetry participants also completed a dichotic listening test. Although women were not less lateralised than men, both tasks consistently revealed that women were more susceptible to left–right confusion than men. However, only women with a significant right ear advantage in the dichotic listening test had more difficulties in LRC tasks than men. There was no sex difference in less lateralised participants. This finding suggests that the impact of functional verbal asymmetries on LRC is mediated by sex.