NEW YORK (Reuters Life!) - Bisexuality in women is not an experimental or transitional phase on the way to lesbianism but a distinct sexual orientation, according to a new study.

Researchers who studied 79 non-heterosexual women over the course of a decade found bisexual women remained attracted to both men and women throughout that time.

"This is the first research that's really followed bisexual women for such a long period of time and it really, I think, puts to rest the notion that this is a transitional stage," said University of Utah psychologist Lisa Diamond, who conducted the study published in the journal Developmental Psychology.

"Because if it were, it should have resolved over a 10-year period. And instead you find that those patterns of nonexclusive desire are pretty stable. The women might change their relationships, they might change the way they identify, but that basic pattern of desire pretty much sticks with them."

Diamond interviewed women who were between the ages of 18 and 25 when the study began and who identified themselves as lesbian, bisexual or unlabeled.

She found that bisexual and unlabeled women were more likely than lesbians to switch their sexual identities, but tended to move between bisexual and unlabeled, rather than settling on lesbian or heterosexual as their orientations.

Although 17 percent of the respondents moved from bisexual or unlabeled to heterosexual during the study, more than half switched back to bisexual or unlabeled by its conclusion.

"Despite our modern day and age it's amazing how persistent some of the negative stereotypes about bisexuality have been. There are still even some researchers, as well as lay people, who are not really sure that it really exists, who have viewed it as a transitional state on the way to lesbianism, or viewed it as just something that some confused heterosexuals will claim about themselves," Diamond explained in an interview.

The research also claims to debunk the popular stereotype that bisexual women are unable or unwilling to commit to long-term (more than a year in length), monogamous relationships.

By year 10, the study shows, 89 percent of the self-identified bisexual women were involved in long-term, monogamous relationships, as were 85 percent of those who preferred to remain unlabeled.

"It's been hard to actually refute those stereotypes because there just hasn't been sufficient data to speak to it. Which is bad for society, but it's also bad in terms of social workers and therapists and folks who have contact with bisexuals. They need to know, for example, that it would be inappropriate to give advice like, 'Well, you know, I know you think you're bisexual but you're probably not,'" Diamond added.