312 Chapter 8 Motivation and Emotion There are differences, too, in what women and men ﬁnd sexually arousing. For example, in many cultures, men are far more interested in, and responsive to, erotic visual images than women are (Herz & Cahill, 1997; Symons, 1979). A biological basis for this difference was investigated in a study that scanned the brain activity of males and females while they looked at erotic photographs (Hamann et al., 2004). As expected, the men showed greater activity in the amygdala and hypothalamus than the women did. But even though there were gender differences in brain activity, the male and female participants rated the photos as equally attractive and sexually arousing. In another study, when men reported sexual arousal in response to erotic ﬁlms, they showed signs of physiological arousal, too. For women, self-reports of arousal were not strongly correlated with signs of physiological arousal (Chivers et al., 2004). These are just a few examples of the fact that sexuality is a product of a complex mixture of factors. Each person’s learning history, cultural background, and perceptions of the world interact so deeply with such a wide range of physiological processes that— as in many other aspects of human behavior and mental processes—it is impossible to separate their inﬂuence on sexuality. Nowhere is this point clearer than in the case of sexual orientation. Sexual Orientation heterosexual Referring to sexual desire or behavior that is focused on members of the opposite sex. homosexual Referring to gay men and lesbians, whose sexual desire or behavior is focused on members of their own sex. bisexual Referring to sexual desire or behavior that is focused on members of both sexes. Sexual orientation refers to the nature of a person’s enduring emotional, romantic, or sexual attraction to others (American Psychological Association, 2002a; Ellis & Mitchell, 2000). The most common sexual orientation is heterosexual, in which the attraction is to members of the opposite sex. When attraction focuses on members of one’s own sex, the orientation is called homosexual, and more speciﬁcally, gay (for men) and lesbian (for women). People who are attracted to members of both sexes are said to have a bisexual orientation. Sexual orientation involves feelings that may or may not be translated into corresponding patterns of sexual behavior. For example, some people whose orientation is gay, lesbian, or bisexual may have sex only with opposite-sex partners. Similarly, people whose orientation is heterosexual may have had one or more same-sex encounters. In many cultures, heterosexuality has long been regarded as a moral norm, and homosexuality seen as a disease, a disorder, or even a crime (Hooker, 1993). Yet attempts to alter the sexual orientation of gay men and lesbians—using psychotherapy, brain surgery, or electric shock—have usually been ineffective (American Psychiatric Association, 1999; Haldeman, 1994). In 1973 the American Psychiatric Association dropped homosexuality from the Diagnostic and Statistical Manual of Mental Disorders, thus ending its ofﬁcial status as a mental disorder. The same change was made by the World Health Organization in its International Classiﬁcation of Diseases in 1993, by Japan’s psychiatric organization in 1995, and by the Chinese Psychiatric Association in 2001. Nevertheless, some people still disapprove of homosexuality. Because gays, lesbians, and bisexuals are often the victims of discrimination and even hate crimes, many of them are reluctant to let their sexual orientation be known (Bernat et al., 2001; Meyer, 2003). It is difﬁcult, therefore, to obtain an accurate picture of the mix of heterosexual, gay, lesbian, and bisexual orientations in a population. In the Chicago sex survey mentioned earlier, 1.4 percent of women and 2.8 percent of men identiﬁed themselves as exclusively gay or lesbian (Laumann et al., 1994). These ﬁgures are much lower than the 10 percent found earlier in Kinsey’s studies. However, the Chicago survey’s face-toface interviews did not allow respondents to give anonymous answers to questions about sexual orientation. Some researchers suggest that if anonymous responses to those questions had been permitted, the prevalence ﬁgures for gay, lesbian, and bisexual orientations would have been higher (Bullough, 1995). In fact, studies that have allowed anonymous responding estimate that gay, lesbian, and bisexual people make up between 2 and 21 percent of the population in the United States, Canada, and Western Europe (Aaron et al., 2003; Bagley & Tremblay, 1998; Binson et al., 1995; SavinWilliams, 2006; Sell, Wells, & Wypij, 1995).