turn-on

Sexual arousal, or sexual excitement, is the arousal of sexual desires in anticipation for sexual activity. Things that precipitate human sexual arousal are colloquially known as turn-ons. Sexual arousal usually leads to physiological changes in the aroused person, some of which are pronounced while others are more subtle.

Human sexual arousal

People can be sexually aroused by different things and in a variety of situations. An arousal may be physical or mental in nature. A person may be sexually aroused by another person or by particular aspects of that person (eg.: hair color, build, smell, smile, etc) or by a non-human object.

When a person is sexually aroused by another person, it may be seen as an indicator of that person's sexual orientation.^{[citation needed]} When sexual arousal is achieved by or dependent on the use of objects, it is referred to as sexual fetishism. This also includes sexual arousal which arises from another person's body part.

Most people are sexually aroused by a physical stimulation of an erogenous zone, especially if it is accompanied with the anticipation of imminent sexual activity.

In addition, some people may find nudity, erotica and pornography sexually arousing, though what aspect different people find arousing will vary. Most heterosexual males are visually stimulated by female nudity or partial nudity, while some heterosexual females are stimulated by the state of romance with their partner.^[1] According to the marital and sex therapist, David Schnarch, intimacy, the honest portrayal of the two people joining in the sexual act, may lead to a heightened state of passion in sex, including sexual arousal.^[2] Such sexual arousal may not lead to an actual sexual activity, beyond a mental arousal. In a 2004 study at Northwestern University, the female participants (both heterosexual and homosexual women) became sexually aroused when they viewed straight as well as lesbian erotic films. Among the male participants, however, the heterosexual men were turned on only by erotic films showing women; the gay males were aroused only by films showing men. The study's senior researcher said that women's sexual desire is less rigidly directed toward a particular gender, as compared with men's; and women's desire is more changeable over time.^[3]

Sexual arousal may also be assisted by a romantic setting, music, or other soothing situations.

Given the right stimulation, sexual arousal in humans will typically end in an orgasm, but may be pursued for its own sake, even in the absence of an orgasm.

Some people may experience a sexual arousal disorder. This may be characterized as a lack or absence of sexual fantasies and desire for sexual activity for a period of time. This may be caused by a mental disorder, such as depression, drug use, or some other medical condition. The lack of sexual arousal may be due to a general lack of sexual desire or due to a lack of sexual desire for the current partner. The lack of desire may be acquired (i.e. it may have started after a period of normal sexual functioning) or life-long (the person has always had no/low sexual desire).

Unlike most animals, human beings of both sexes are potentially capable of sexual arousal throughout the year; therefore, there is no human mating season.

Physiological changes

Sexual arousal for a man is usually indicated by the swelling and erection of the penis when blood fills the corpus cavernosum. This is usually the most prominent and reliable sign of sexual arousal in males; however, adolescent males experience 'non-sexual' erections stemming from high levels of testosterone.
In a woman, sexual arousal usually leads to vaginal lubrication in anticipation of sexual intercourse. Sexual arousal causes different physical changes.^{[citation needed]}

In females:

In males:

Female sexual arousal. In the left image female genitalia are in normal state. In the right image the female is sexually aroused, the vulva is wet and the labia are slightly engorged. Increase in breast size[citation needed] Erection of nipples[4] Vaginal lubrication Vasocongestion of the vaginal walls Tumescence and erection of the clitoris and labia Elevation of the cervix and uterus, and expansion of the back of the vagina Change in shape, color and size of the labia majora and labia minora Pupil dilation

Male sexual arousal. Penile tumescence and erection The veins in the penis may become more prominent Tightening and/or retraction of the foreskin (unless circumcised) often exposing the glans penis Emission of pre-ejaculatory fluid Swelling of the testes Ascension of the testes Tensing and thickening of the scrotum Pupillary response

Human sexual response cycle

During the 1950s and 1960s, William H. Masters and Virginia E. Johnson conducted many important studies within the field of human sexuality. In 1966, they released a book, Human Sexual Response, detailing four stages of physiological changes in humans during sexual stimulation. These phases, in order of their occurrence, are excitement, plateau, orgasm, and resolution.^[5]

The effect of sexual response is thought to be a plastic positive reinforcement behavior modifier associated with the Baldwin Effect. The end result of these sorts of things can be very novel structures such as the Pseudo-penis of the female Spotted Hyena.^[6] The display of secondary sex characteristics in humans such as a penis-like enlarged clitoris in females during arousal and gynecomastia in males are thought to have once been objects of mate selection in human evolution because of the persistence of the phenomenon of these features invoking sexual arousal for potential mates in cross-cultural studies.^[7] A dramatic example of this is the high rates of secondary sex characteristic dimorphism in some Southeast Asia human populations.^[8]

Singer's model of sexual arousal

Singer^[9] presents a model of the process of sexual arousal, in which he conceptualized human sexual response to be composed of three independent but generally sequential components. The first stage, aesthetic response, is an emotional reaction to noticing an attractive face or figure. This emotional reaction produces an increase in attention toward the object of attraction, typically involving head and eye movements toward the attractive object. The second stage, approach response, progresses from the first and involves bodily movements towards the object. The final genital response stage recognizes that with both attention and closer proximity, physical reactions result in genital tumescence. Singer also notes that there is an array of other autonomic responses, but acknowledges that the research literature suggests that the genital response is the most reliable and convenient to measure in males.

Sexual arousal in animals

While human sexuality is well understood, scientists do not completely grasp how other animals relate sexually. However, current research studies suggest that many animals, like humans, enjoy sexual relations that are not limited to reproduction. Dolphins and Bonobos, for example, are both well known to use sex as a "social tool to strengthen and maintain bonds."^[10] Ethologists have long documented the exchanges of sex to promote group cohesion in social animals. Cementing social bondage is one of the most prominent theorized selective advantages of group selection theory. Experts in the evolution of sex such as John Maynard Smith advocate for the idea that the exchange of sexual favors helps congeal and localize the assortment of alleles in isolated population and therefore is potentially a very strong force in evolution. Maynard Smith also has written extensively on the "seminal fluid swapping theory" logistic application of the assortment of alleles as a more accurate synthetic depiction of the Hardy Weinberg Equilibrium in cases of severely interbreeding populations.

See also

References