sexual perversion, in psychology, sexual behavior deemed pathological by its deviation from "normal" sexual desire. The definition of sexual perversion has shifted considerably over time: indeed, it has never been an uncontested category of meaning. For example, homosexual desire has long been stigmatized as sexual perversion among many segments of Western society (and remains so among some), but within the field of psychology, it is no longer considered pathological. Use of the term perversion itself has come under wide criticism in recent years. Today, psychologists generally refer to nontraditional sexual behavior as sexual deviation or, in cases where the specific object of arousal is unusual, as paraphilia. There are a number of recognized disorders of this type. In fetishism, the object of sexual desire is either an inanimate object or a nongenital part of the human anatomy. Voyeurism involves the covert viewing of other individuals who are naked, undressing, or engaged in sexual activity, as the primary means of sexual arousal. Sexual arousal as a result of physical contact with prepubescent children is described as pedophilia. Other forms of sexual deviation include exhibitionism, incest, transvestism, necrophilia, sadism, and masochism. Many of these behaviors, when they involve the participation of nonconsenting adults (or children, consenting or not), are punishable by law. Although rape is not classified as a paraphilia, it is a serious sexual deviance, and perhaps the most highly reviled form of sexual gratification. Most forms of sexual deviance are accompanied by any number of other psychological disorders.
See V. Bullough, Sexual Variance in Society and History (1980).