Sex difference in language lateralization may be task-dependent.

Sir, It has been proposed that language is more strongly lateralized in males than in females. Recent imaging studies, however, have yielded a variety of apparently contradictory observations. A meta-analysis by Sommer et al . (2004) has provided us with an up-to-date collection of 24 studies in which language-related activity was assessed with functional imaging techniques in healthy subjects. By combining 14 studies with sufficient data, which employed a variety of language tasks, Sommer and colleagues concluded that ‘sex difference in language lateralization may be absent at the population level’. They further suggested that ‘sex difference in language lateralization may be observed only with some, as yet not defined, language tasks’, because they ‘found no support for’ the hypothesis that ‘sex differences in language lateralization may be task-dependent’. In our previous review of this topic (Kansaku and Kitazawa, 2001), we suggested, on the contrary, that sex differences in language lateralization are task-dependent, and drew attention to the fact that studies that employed passive listening to stories found clear sex-based differences (Kansaku et al ., 2000; Phillips et al ., 2001). Although Sommer and colleagues referred to our study (Kansaku and Kitazawa, 2001), we believe that the authors were not entirely accurate in their interpretation of our paper. Sommer et al . (2004) stated that ‘Kansaku and Kitazawa (2001) suggested that only tasks …