Bisexuality has been a controversial subject within lesbian circles, and the place of bisexual women within "women's communities" has often generated heated debates. Some lesbians believe that all women who have the potential to love other women have an obligation to do so, and a political obligation to identify as lesbian and cease interacting with men. Others believe that the compulsory nature of heterosexuality in our cultures precludes the possibility of a woman freely "choosing" a heterosexual relationship, some going so far as to believe that due to the negative pressures on people in same sex relationships, and the positive benefits attached to opposite sex relationships, a bisexual woman will inevitably end up leaving a woman partner for one of the other sex. As a result of these lines of thought, bisexually-identified women have often had their integrity and their commitment to feminism questioned. A study conducted in the late 1980s by sociologist Paula Rust found that most lesbian respondents held far more negative than positive view of bisexuality, though she emphasizes that lesbians are by no means unanimous in their views, with some holding positive opinions about bisexual women. Political shifts in the 1990s have doubtless shifted the landscape of opinion toward a greater acceptance of bisexuality.