Rigid sexual orientations have defined the preference of men and women for decades; however, a new study is attempting to do away with strict definitions of sexuality.

The study, published in the Journal of Personality and Social Psychology, argues that there’s no such thing as a “straight” man or woman. Rather, people operate on a spectrum.

Researchers showed men and women different kinds of pornographic material.

Rather than relying on self-reporting, the study looked at physiological responses to the sexual material. Namely pupil dilation, which is a sign of sexual arousal.

The study found that women’s eyes dilated when they viewed a man and a woman being sexuality intimate, and when two women were sexually intimate.

Lesbian are more aroused to their preferred sex than the other sex, a pattern normally seen in men.

A similar phenomenon was seen in men. Talking to Broadly, study author Ritch C Savin-Williams, who is also the Director of Developmental Psychology at Cornell University, said:

We show straight men a picture of a woman masturbating and they respond just like a straight guy, but then you also show them a guy masturbating and their eyes dilate a little bit. So we're actually able to show physiologically that all guys are not either gay, straight, or bi.

He argues that though the idea of bisexuality as the norm is becoming more accepted when it comes to women, men are still struggling with patriarchal stigma.