Examining the sex difference in lateralisation for processing facial emotion: does biological sex or psychological gender identity matter?

The research examining sex differences in functional lateralisation has shown varying results. While some provide evidence for males being more strongly lateralised than females, a number have shown either no relationship or the opposite pattern of findings. In this study we consider whether psychological gender identity might clarify some of the conflicting results in this area of research. Eight five participants (39 males) aged from 18 to 49 years old were tested. We found that psychological masculinity was associated with stronger patterns of lateralisation for the processing of a range of emotional expressions. We also found an interaction between biological sex and psychological gender identity, with a positive relationship between psychological masculinity and lateralisation found for males, but a negative relationship found for females. The possible role of hormonal exposure in this relationship is discussed.