A comparative analysis of functional cerebral asymmetry in lesbian women, heterosexual women, and heterosexual men.

This study tested dichotic listening performance, a measure of functional cerebral asymmetry previously shown to be sexually dimorphic, in homosexual women (n=23), heterosexual women (n=27), and heterosexual men (n=24). All participants completed a verbal consonant-vowel dichotic listening task. On three laterality indices, heterosexual men displayed a significantly greater right-ear advantage compared to heterosexual women only. Homosexual women did not differ significantly from heterosexual men or from heterosexual women. Post-hoc comparisons (with a statistical correction) for each ear separately showed that heterosexual men displayed significantly greater right-ear scores compared to heterosexual women only. These data suggest that lesbian women are somewhat masculinized in their functional cerebral asymmetry. The results were interpreted in the context of sexual variation in models of linguistic hemispheric processing.