Outnumbered by opposite sex -- men like it, women feel wary: study

"Walking into a situation in which you sense the possibility of being ostracized or isolated can be quite threatening," said the study, which looked at the effect of so-called situational cues, such as being outnumbered, on women's performance in math, science and engineering courses.

The gender ratio in those classes is "approximately three men to every one woman," said the study, led by Mary Murphy, a psychologist at Stanford University in California.

Published in the October issue of Psychological Science, the study monitored the reactions of a group of advanced students in traditionally male-dominated fields while they watched videos depicting a conference.