Sexual orientation and visuo-spatial ability.

On the basis of a literature review it was concluded that sex differences in cognitive ability and the etiology of male homosexuality may have a common biological base, leading to the prediction that in terms of cognitive ability homosexual males (HmM) would resemble heterosexual females (HtF) rather than heterosexual males (HtM). This prediction was investigated using visuo-spatial tasks on which males are known to perform better than females. In Experiment 1 HtM performed better on a water level task than HmM and HtF whose performances did not differ significantly. A different version of the water level task and the Vincent Mechanical Diagrams Test were used in Experiment 2; on both tasks the HtM performed better than the HmM and the HtF whose performance did not differ significantly. The results are interpreted as support for a common biological determinant of cognitive ability and male sexual orientation.