The interaction between tops and bottoms—where physical or mental control of the bottom is surrendered to the top—is sometimes known as power exchange, whether in the context of an encounter or a relationship. Anti-pornography psychologist Ana Bridges and colleagues conducted a content analysis of best-selling heterosexual pornographic videos showing that over 96% of all scenes concluded with a male performer ejaculating onto the mobile porn videos body of his female partner. They are often made out of precious woods, with leather used for the seat. It may involve sexual attraction to women who are pregnant or appear pregnant, attraction to lactation, or attraction to particular stages of pregnancy such as celeb sextapes impregnation or childbirth. Some productions are noted for sophisticated and/or experimental storytelling and animation techniques. This yields a view that would not be obtainable directly through the eyes of a person while experiencing the sex act. Non-contact group More than two people masturbating in the presence of each other in a group but not touching each other. Contact mutual masturbation One person touching another person to masturbate. The surfacing of sex tapes has become so common that some are leaked as a marketing tool to advance or establish a media career. Pornographic films or sex films are films that present sexually explicit subject matter for the purpose of sexual arousal and erotic satisfaction of the viewer. The anal and rectal tissues are delicate and do not provide natural lubrication, so they can easily tear and permit disease transmission, especially if lubricant cartoon porn movies is not used. In the 1970s, the hardcore pornography genre introduced the stereotypical cumshot scene as a central element of the hardcore film, in which the male actor ejaculates in a way ensuring maximum visibility of the act itself. Various groups within society have considered depictions of a sexual nature immoral, labeling them pornographic, and attempting to have them suppressed under obscenity and other laws, with varying degrees of success.