New York, Sep 4 (IANS): Gaydar - the so called ability to infer whether people are gay or straight based on their appearance - is just a myth that promotes harmful form of stereotyping, says a new study.

"Most people think of stereotyping as inappropriate," said lead author William Cox, assistant scientist at University of Wisconsin-Madison.

"But if you are not calling it 'stereotyping,' if you are giving it this other label and camouflaging it as 'gaydar,' it appears to be more socially and personally acceptable," Cox explained.

The researchers challenged a 2008 study that concluded people could accurately guess someone's sexual orientation based on photographs of their faces.

Cox and his team questioned the validity of the previous research, citing differences in the quality of the photos used for the gay and straight people featured in the study.

The gay men and lesbians, according to Cox's studies, had higher quality pictures than their straight counterparts.

When researchers controlled for differences in photo quality, participants were unable to tell who was gay and straight.

In one of the studies, Cox and his team manipulated what participants understood about gaydar by providing different explanations of gaydar for three groups.

The researchers told one group that gaydar is real, told another that gaydar is stereotyping, and did not define gaydar for the third group.

The group that was led to believe gaydar is real stereotyped much more often than the other groups, assuming that men were gay based on the stereotypic cues -- statements such as "he likes shopping."

"If you tell people they have gaydar, it legitimises the use of those stereotypes," Cox says.

That is harmful because stereotypes limit opportunities for members of stereotyped groups, narrowing how we think about them and promoting prejudice and discrimination -- even aggression, he pointed out.

The study was published in the Journal of Sex Research.