What turns us on and where we place ourselves on the sexual spectrum is exceedingly personal. A new study investigating the existence of this spectrum may prove somewhat controversial, then: It claims that women are almost always gay or bisexual and are almost certainly not straight. The research has been accepted for publication in the Journal of Personality and Social Psychology.

Previous studies using volunteers to investigate the sexual arousal of both men and women have been conducted. Many have suggested that women are, on average, physiologically aroused – as in, showing physical changes in their bodies indicating attraction – to both male and female sexual stimuli. The same is apparently not true for lesbians as, surprisingly, they are significantly more aroused by their own sex than by the opposite sex.

This new study, led by Dr. Gerulf Rieger from the Department of Psychology at the University of Essex, asked 345 women of varying sexual orientations to watch a series of videos featuring sexual content. At the same time, their biological responses were measured, including their pupil dilation and their genital response (pulse and blood flow).

The subjects were women ranging in age, educational background, and ethnicity. They were asked to place themselves on a sexual spectrum scale, identifying themselves as either “straight,” “mostly straight,” “bisexual leaning straight,” “bisexual,” “bisexual leaning lesbian,” “mostly lesbian,” or “lesbian.”

The results indeed found that women who identified as heterosexuals were, on average, strongly aroused by videos of both attractive men and women. In contrast to this, self-identified lesbians exhibited a far stronger response to women than men, which the researchers likened to the responses of heterosexual men: both groups show proportional levels of attraction to their self-identified sexual orientation.

A major criticism this paper is likely to receive when it is published is that arousal is not precisely the same as sexual orientation, despite the language of the lead author suggesting so in the media. “Even though the majority of women identify as straight, our research clearly demonstrates that when it comes to what turns them on, they are either bisexual or gay, but never straight,” Dr. Rieger said, as reported by Pink News.

The study notes that, unlike men, a woman’s sexual attraction may be less affected by a partner’s sex and more influenced by cultural and social factors; these factors include relationship history, educational experiences, religious beliefs and cultural assimilation. As a result of this, a woman’s sexual attitude may vary far more than a man’s, and studies such as this one – and others – appear to back this idea up. Hormonal exposure levels from a young age are also cited as a possible explanation for the general variability in responses to sexual stimuli.

It’s a distinctly tricky subject: The authors of the study also mention that “there is considerable variability across sex in physiological sexual arousal to male or female stimuli.” They point out that their research base falls into the Western, Educated, Industrialized, Rich and Democratic – or WEIRD – demographic, and thus their results cannot be accurately applied to the wider populace just yet.