Biphobia is a term used to describe the fear of, aversion to, or discrimination against bisexuality or LGBT people who are bisexual or perceived to be bisexual. It can also mean hatred, hostility, disapproval of, or prejudice towards LGBT people, sexual behavior, or cultures. Biphobic is the adjective form of this term used to describe the qualities of these characteristics while the less common biphobe is the noun form given as a title to individuals with "biphobic" characteristics. It need not include or exclude homophobia, or lesbophobia, because there are stereotypes that are specific to bisexuals.
Bisexual stereotypes include, but are not limited to: promiscuity, polygamy, living the swinging lifestyle, and being "confused", "greedy" or "slutty". In some cases, bisexuals are accused of bringing sexually transmitted diseases into the heterosexual community or into the LGBT community. A related stereotype is one in which a bisexual person is presumed to be willing to have sex with just about anyone. This stereotype leads to unwanted attention of a sexual nature directed at bisexual females, while often stereotyping bisexual males as major AIDS risks.
Often, however, heterosexuals will add more stereotypes based on homophobia. Homophobes often think that bisexuals are gender nonconformist. Homosexual people will sometimes see bisexuals as maintaining privilege and collaborating with the homophobes while simultaneously availing themselves of opportunities in LBGT communities. Some consider the belief that people are either heterosexual or homosexual, and thus that bisexuality does not truly exist, to be biphobic.
A 2002 study said that a sample of men self-identifying as bisexual did not respond equally to pornographic material involving only men, and to pornography involving only women, but instead showed four times more arousal to one than the other. However, bisexuality does not imply equal attraction towards both genders. In addition, opponents state that genital arousal to homosexual pornographic material is not a good indicator of orientation. They also point out that the study showed a third of men had no arousal, and ask why this does not mean that one third of men are really asexual. The study, and The New York Times article which reported it in 2005, were subsequently criticized as flawed and biphobic. Lynn Conway criticized the author of the study, J. Michael Bailey, citing his controversial history, and pointing out that the study has not been scientifically repeated and confirmed by any independent researchers.
Conversely, there is a school of thought that says that "everyone is bisexual." One common motive for negative attitudes toward bisexuality, for straight partners of bisexuals, is the fear that their bisexual partner will leave them for a member of the same sex. Similar fears exist among gay people as well.
The heterosexual male is seen as having an unfair systemic advantage due to both sexism and homophobia. Bisexual persons may also be the target of homophobia from those who consider only heterosexuality appropriate.
Some radical lesbian feminists think that bisexual women are giving in to patriarchy. Others say that people against bisexuals are insecure about their sexuality themselves, similarly to homophobia. It is fair to note many anti-bisexuals are also homophobic, while maintaining there are only heterosexual and homosexual as sexual preferences, and a common stereotype is that female bisexuals are attention seeking heterosexuals, while male ones are just self-denying homosexuals too afraid to fully acknowledge their true orientation.