Homosexuality and cognition
hypothesis that there is a neurobiological basis for sexual orientation has
received substantial attention recently - examples being the anatomical
difference found in the brains of some male homoseuals; new evidence of a strong
genetic role in homsexuality, and the association found between homosexuality
and left-handedness. Now the hypothesis has gotten a boost from yet another
direction - research bearing on sex differences in cognitive abilities.
Scientists at McMaster University in Ontario report in the latest issue of
Psychoneuroendocrinology [whew!] that on measures of visual spatial ability
where consistent differences have been observed between males and females, male
homsexuals fall between the two sexes.
"It is as if, in some cognitive respects, they are neurologically a third sex,"
says neuroscientist Sandra Witelson, who co-authored the paper with psychologist
Cheryl M McCormick (now at McGill University).
The researchers administered three tests of spatial ability (where males excel)
and two measuring verbal fluency (where felales show a small advantage) to three
groups of 38 subjects each: homosexual men, heterosexual men, and heterosexual
women, "The cognitive pattern of homosexual men was significantly different from
heterosexual men but not significantly different from that of heterosexual women,"
says Witerson. The results - like those from other studies on homosexuality -
are consistent with the hypothesis that homosexuals are exposed to atypical
levels of prenatal sex hormones.
In the spatial tests, heterosexual males had the highest scores, followed by
homosexual males, and then females. This pattern was particularly pronoun ced
among right-handers in a test where subjects had to visualize the water level in
a tilted glass. In a measure of verbal fluence the order was reversed: Women
scored highest, followed by the homosexuals, and then the heterosexual men.
Witelson believes that evidence fom anatomical, genetic, hormonal, and
neuropsychological research is converging to suggest that "sexual orientation...
is part of a larger constellation of cognitive attributes." She adds that all
this may lead to an explanation for the "apparently greater prevalence and
ability of homosexual men compared to heterosexual men in some professions." But
the bewilderingly complex relationships between brain anatomy, prenatal sex
hormones, handedness and homosexuality still need a lot more sorting out.