Cultural history of the buttocks desirability of buttocks: Since the early 2000s, songs about the female buttocks have proliferated, especially in the hip-hop, reggae/dancehall, and R&B genres. Buttocks are often emphasized in pornography. Patricia Hill Collins, an African-American post-modern feminist writer, theorizes that this is derived from a stereotype that black women are promiscuous, and their buttocks are objectified by pornography as a result. A buttocks fetish or buttocks partialism refers to a condition wherein the buttocks becomes a primary focus of sexual attention. It may be associated with coprophilia, panty fetishism, eproctophilia, and sadomasochistic corporal punishment involving the buttocks. "Pygophilia" refers to sexual arousal
Sexual arousal characterized by vasocongestion of the genital tissues, including internal and external areas (e.g., vaginal walls, clitoris, and labia). There are a variety of methods used to assess genital sexual arousal in women. Vaginal photoplethysmography (VPG) can measure changes in vaginal blood volume or phasic changes in vasocongestion associated with each heartbeat. Clitoral photoplethysmography functions in a similar way to VPG, but measures changes in clitoral blood volume, rather than vaginal vasocongestion. Thermography provides a direct measure of genital sexual arousal by measuring changes in temperature associated with increased blood flow to the external genital tissues. Similarly, labial thermistor clips measure