After having male and female participants look at videos of both naked men and naked women, researchers found that self-identified “straight” women became aroused when looking at naked women.

This study builds off previous research which has found women are generally sexually aroused by men and women to varying degrees (we all exist on a continuum; no one is purely gay or straight, the theory goes).
New research suggests that women who identify as heterosexual “very rarely are”. Rieger, who published his findings in the Journal of Personality and Social Psychology, later clarified that “never” might be too strong of a word, saying instead that, “the majority of women who identify as straight are not straight in their sexual arousal”.
A few women insist that the results do not point to bisexual or gay orientation so much as they do to women’s ability to appreciate female beauty more than men do with others of their own sex. Nor does sexual response itself translate cleanly to attraction, as Dr. Reiger himself acknowledged to Mic when he ceded that self-lubrication may occur in women as a form of protection from sexual assault, not just as an expression of arousal.
Now this primarily proves that women are attracted to their own kind, and are positively turned on by other nude and attractive women.
Dr Rieger also said his study showed that lesbians who may dress in a more masculine way may not have more masculine behaviours.
And because of that the way women appear in public does not mean we know what their sexual role preferences are.
Led by Doctor Gerulf Rieger from the Department of Psychology at the University of Essex, the study showed several videos of naked men and women to 235 women and gauged their responses.