and identity match, scientists usually use the terms concordance or discordance. Thus, a woman who is attracted to other women, but calls herself heterosexual and only has sexual relations with men, can be said to experience discordance between her sexual orientation (homosexual or lesbian) and her sexual identity and behaviors (heterosexual). Sexual identity may also be used to describe a person's perception of their own sex, rather than sexual orientation. The term sexual preference has a similar meaning to sexual orientation, and the two terms are often used interchangeably, but the American Psychological Association states sexual preference suggests a degree of voluntary choice. The term has been listed by the American Psychological Association's Committee on Gay and Lesbian Concerns as a wording that advances a "heterosexual bias". The term sexual orientation was introduced by sexologist John Money in place of sexual preference, arguing that attraction is not necessarily a matter of free choice. Androphilia, gynephilia, and other terms Androphilia and gynephilia (or gynecophilia) are terms used in behavioral science to describe sexual attraction, as an alternative to a homosexual and heterosexual conceptualization. They are used for identifying a subject's object of attraction without attributing a sex assignment or gender identity to the subject. Related terms such as pansexual and polysexual do not make any such assignations to the subject. People may also use terms such as queer, pansensual, polyfidelitous, ambisexual, or personalized identities such as byke or biphilic. Using androphilia and gynephilia can avoid confusion and offense when describing people in non-western cultures, as well as when describing intersex and transgender people. Psychiatrist Anil Aggrawal explains that androphilia, along with gynephilia,is needed to overcome immense difficulties in characterizing the sexual orientation of trans men and trans women. For instance, it is difficult to decide whether a trans man erotically attracted to males is a heterosexual female or a homosexual male; or a trans woman erotically attracted to females is a heterosexual male or a lesbian female. Any attempt to classify them may not only cause confusion but arouse offense among the affected subjects. In such cases, while defining sexual attraction, it is best to focus on the object of their attraction rather than on the sex or gender of the subject.Sexologist Milton Diamond writes, "The terms heterosexual, homosexual, and bisexual are better used as adjectives, not nouns, and are better applied to behaviors, not people. This usage is particularly advantageous