According to a study published this week, people may be able to determine at a glance whether another person is gay.

A University of Washington study published in the Public Library of Science found that people were often able to accurately guess another person’s sexuality by briefly looking at their face.

129 students, 92 of whom were women, were shown black and white photos of a woman or a man for 50 milliseconds and were able to guess the sexual orientation of the subject with above-chance accuracy.

Participants guessed women’s sexuality accurately 65 percent of the time and men’s sexuality accurately 57 percent.

Study authors say it is not completely clear how the snap judgements are formed, but believe the results show ‘configural processing’, quickly identifying how another person’s face is made up in terms of distance between features, and ‘featural processing’, examining individual features, helps people determine sexuality.

As part of the investigation, students were shown images of men and women for a fraction of a second the right way up and images upside down, when ‘configural processing’ is impaired.

Success in guessing the sexuality of another person upside down was less, but it was still above a rate of chance.

Joshua Tabak, a psychology student at the University of Washington said: “It may be similar to how we don’t have to think about whether someone is a man or a woman or black or white.

“This information confronts us in everyday life.”

Tabak added that “people from older generations or different cultures who may not have grown up knowing they were interacting with gay people” were less able to guess sexuality accurately.

The study paper itself suggested that if the results are accurate, “it would appear that minority sexual orientation is not the concealed stigma that many argue it is. Indeed, the need to protect gay people from discrimination would seem increasingly urgent to the extent that minority sexual orientation is tacitly inferred from aspects of personal appearance that are routinely available for inspection (e.g., faces).”