Some techniques which may work for one individual hentai porn can be difficult or uncomfortable for another. As of 2013, little analysis of this paraphilia has been reported in medical literature. Comic books often featured characters being tied up and tying others up, particularly in damsel in distress plots. Reality pornography is professionally made porn which seeks to emulate the style of amateur pornography. Originating in Japan in the 1980s, the genre subsequently spread to North America and momsex Europe, and crossed over into gay pornography. The term combines elements of the Freudian psychoanalytic fetish and the Marxist commodity fetish, and is used in the context of British, Spanish and French colonialism and imperialism and their aftereffects. These scenes may involve the female actor calling for the shot to be directed at some specific part of her body. The most common type of erotic spanking is administered on the bare buttocks, but can also be combined with bondage, in order to heighten sexual arousal and feelings of helplessness. Related genres include: Amateur pornography originally referred only to pornography produced by amateurs but now also includes professionally made pornography designed to appear as if it were amateur. Pornography is often distinguished from erotica, which consists of the portrayal of sexuality with high-art aspirations, focusing also on feelings and emotions, while pornography involves the depiction of acts in a sensational manner, with the entire focus on the physical act, so as to arouse quick intense reactions. The rise of the Internet in the late 1990s and early 2000s similarly changed the way pornography film was distributed and furthermore complicated the censorship regimes around the world and the legal prosecution of obscenity. Bisexual pornography is a genre of pornography which most typically depicts one woman and two men who all perform sex acts on each other. Double Stuffed , Double Vaginal , or Double Anal pornography involves gay cock the penetration of one orifice by two penises or other objects.