Washington: A woman can more accurately identify a man``s sexual orientation by looking at his face when she is closest to ovulation, according to a study by psychologists at the University of Toronto and Tufts University.
Further, having romantic thoughts or a mating goal heightens a woman``s ability to discriminate between straight and gay men, their report said.
"This effect is not apparent when a woman is judging another female``s orientation," said Professor Nicholas Rule of the Department of Psychology at the University of Toronto and lead author of the study.
"This suggests that fertility influences a heterosexual woman``s attention to potential mates rather than merely increasing sensitivity to sexual orientation or nonverbal cues more generally,” he added.
In the first of three experiments, 40 undergraduate women judged the sexual orientation of 80 images of men``s faces. Forty of the photos were of self-identified gay males while the other 40 were of straight men.
The men did not differ in emotional expression or attractiveness, and the female participants were encouraged to use their intuition in making judgments. In addition, the women reported the length of time since their last menstrual cycle and its average duration; none were using any systemic contraceptive medications.
The researchers correlated the participants`` accuracy in judging sexual orientation with the point at which the women were in their fertility cycle, and found that the nearer women were to peak ovulation, the more accurate they were at judging each male``s sexual orientation.
The findings have been published in Psychological Science.