Auditory cerebral lateralization following cross-gender hormone therapy

In this study, 10 men, 10 women, and 13 genetic male transsexuals, all of them righthanded, were tested on two verbal (CV and nonsense polysyllables) and two nonverbal (melodies and triple tone [3T]) dichotic tasks to investigate relations between hormone therapy and auditory cerebral specialization for speech and non speech stimuli in adults. At time of testing, all transsexuals had been made under hormonal treatment for at least one year and eight had had corrective surgery. ANOVA results showed a right ear advantage and similar pattern of performance for the three groups in the treatment of speech. In nonverbal tasks, interactions revealed a left ear advantage in the processing of melodies and 3T for men only: women and transsexuals exhibited similar performance in both nonverbal tasks. In accord with generalization from the animal literature, cautious interpretation of the data is some possible hormonal involvement, in adults, in the modulation of right hemispheric cognitive processing.