quality:correction, structural:expansion
Kinsey scale

In the 1940s, the zoologist Alfred Kinsey created a scale to measure the continuum of sexual orientation from heterosexuality to homosexuality. Kinsey studied human sexuality and argued that people have the capability of being hetero- or homosexual even if this trait does not present itself in the current circumstances. The Kinsey scale is used to describe a person's sexual experience or response at a given time. It ranges from 0, meaning exclusively heterosexual, to 6, meaning exclusively homosexual. People who rank anywhere from 2 to 4 are often considered bisexual; they are often not fully one extreme or the other. The sociologists Martin S. Weinberg and Colin J. Williams write that, in principle, people who rank anywhere from one to five could be considered bisexual.

Psychologist Jim McKnight writes that while the idea that bisexuality is a form of sexual orientation intermediate between homosexuality and heterosexuality is implicit in the Kinsey scale, that conception has been "severely challenged" since the publication of Homosexualities (1978), by Weinberg and the psychologist Alan P. Bell.