Potentially, one of the most fruitful sources of insight into sexual development is the phenomenon known as transsexuality, whereby the individual “knows” he or she is better suited to life in the gender opposite to that of birth assignment and usually transitions gender to effect such a life. Such studies have begun to clarify some of the complex biological underpinnings of human sexuality and have been complemented by many reports of cognitive function that have teased out some of the psychological differences between the sexes (Halpern, 2000 Kimura, 1999). The best known studies are probably those of females with congenital adrenal hyperplasia (CAH) by Berenbaum (1990) and Hines (2004), the anatomical studies of brains of androphilic males (LeVay, 1991), and those of the brains of transsexual people (Kruijver, 2000 Swaab, 2004). Research into the sexing of human brains has also been carried out and comes from diverse sources. Much of this research has been evaluated by Morris, Jordan, and Breedlove (2004) who conclude that the interaction between hormones and genes should now be the focus of research. This view of human sexuality rests on the supporting data from animal studies, ranging from the classic research on the administration of testosterone to pregnant female guinea pigs (Phoenix, Goy, Gerall, & Young, 1959), to the work of Beach (1976) on the induced masculinization or feminization of animals, to the work of Goy, Bercovitch, and McBrair (1988) on the masculinization of female primates and Gorski’s (1991) research on sexuality in rats. In recent times, the focus of the debate has moved closer to the biased interaction theory (BIT) of psychosexual development.Įssentially, this theory proposes that adult “behavior is a composite of prenatal and postnatal influences with the postnatal factors superimposed on a definite inherently biased sexuality” (Diamond, 1965, p.169 Diamond, 2006). The complex interaction of the social environment and the biological substrate in the sexual development of the individual has provoked intense debate. INTRODUCTION Brain Organization and Sexuality Transsexual, dichotic listening, handedness, lateralization, brain Taken together, the dichotic and handedness data reported here indicate that the MtF and FtM conditions are not mirror images in terms of the verbal-auditory aspects of their brain organization and neurobiology plays an important role, particularly in the development of the male-to-female trans-condition.

Finally, it was hypothesized that there would be significantly more nonexclusive right-handers in both trans-groups. It was also hypothesized that the FtM dichotic pattern would be significantly different from the control females and would resemble the control male pattern. It was hypothesized that the MtF participants’ dichotic performance would be significantly different from the control males and resemble the control female pattern. A sex-differentiating dichotic test and a handedness questionnaire were administered. This study investigated the functional brain organization of 68 male-to-female (MtF) transwomen and 26 female-to-male (FtM) transmen by comparing their performance with 36 typical male and 28 typical female controls on two indicators of cerebral lateralization: dichotic listening and handedness. Teresa Wolowiec and Catherine Slade are research assistants at the University of East London in London, United Kingdom.Īddress correspondence to Ernest Govier, University of East London, School of Psychology, Romford Road, London E15 4LZ, UK. Milton Diamond, PhD, is a professor and Director of the Pacific Center for Sex and Society in Honolulu, Hawaii. The Eugene Garfield Foundation of Philadelphia, Pennsylvania, deserves credit for partial support of this research.Įrnest Govier, AFBPS, is Senior Visiting Research Fellow at the University of East London in London, United Kingdom. Richard Curtis for his support and for providing his facilities at the London Gender Clinic, without which it would not have been possible to carry out this research. Published in: International Journal of Transgenderism, 12:144–154, 2010

Title: Dichotic Listening, Handedness, Brain Organization and TranssexualityĪuthors: Ernest Govier, Milton Diamond, Teresa Wolowiec, and Catherine Slade

Isham 2000 dichotic listening