If and how often people masturbate depends on many things. One of the things it depends on is hormone levels. Hormones influence sexual arousal. Other things that the frequency of masturbation depend on are sexual habits. Sexual habits are sexual activities that people do because they are used to doing them. Other people of the same age or standing - called peers - can also influence this frequency. General health is another of the many factors. The general attitude towards masturbation is formed by culture. Medical causes have also been associated with masturbation.
"Forty-eight female college students were asked to complete a sexual attitudes questionnaire in which a frequency of masturbation scale was embedded. Twenty-four of the women (the experimental group) then individually viewed an explicit modeling film involving female masturbation. One month later, all subjects again completed the same questionnaire. Subjects in the experimental group also completed a questionnaire evaluating aspects of the film. Results indicated that the experimental group reported a significant increase in the average monthly frequency of masturbation, as compared to the control group. This same group, however, reported that the film had no effect on sexual attitudes or behavior."
A 2004 survey by Toronto magazine "NOW" was answered by an unspecified number of thousands. The results show that an overwhelming majority of the males — 81% — began masturbating between the ages of 12 and 15. Among females, the same figure was a more modest majority of 55%. (Note that surveys on sexual practices are prone to "self-selection bias".) It is not uncommon, however, to begin much earlier, and this is more frequent among females: 18% had begun by the time they turned 12, and 6% already by the time they turned 10. Being the main outlet of child sexuality, masturbation has been observed in very young children. In the book "Human Sexuality: Diversity in Contemporary America", by Strong, Devault and Sayad, the authors point out, "A baby boy may laugh in his crib while playing with his erect penis (although he does not ejaculate). Baby girls sometimes move their bodies rhythmically, almost violently, appearing to experience orgasm."
A 2004 magazine survey in Canada found that 43% started masturbating when they were about 12–13 years old. When boys start masturbating, wet dreams often stop since semen is taken out from his body regularly.
According to a Canadian survey of "Now" magazine readers, (cited above), the frequency of masturbation declines after the age of 17. However, most males masturbate daily, or even more frequently, well into their 20s and sometimes far beyond. This decline is more drastic among females, and more gradual among males. While females aged 13–17 masturbated almost once a day on average (and almost as often as their male peers), adult women only masturbated 8–9 times a month, compared to the 18–22 among men. It is also apparent that masturbation frequency declines with age. Adolescent youths report being able to masturbate to ejaculation six or more times per day, though some men in older middle age report being hard pressed to ejaculate even once per day. The survey does not give a full demographic breakdown of respondents, however, and the sexual history of respondents to this poll, who are readers of an urban Toronto lifestyle magazine, may not extend to the general population.
It appears that females are less likely to masturbate while in a heterosexual relationship than men. Both sexes occasionally engage in this activity, however, even when in sexually active relationships. Popular belief asserts that individuals of either sex who are not in sexually active relationships tend to masturbate more frequently than those who are; however, much of the time this is not true as masturbation alone or with a partner is often a feature of a relationship. Contrary to conventional wisdom, several studies actually reveal a positive correlation between the frequency of masturbation and the frequency of intercourse as well as the number of sex partners. One study reported a significantly higher rate of masturbation in gay men and women who were in a relationship.
The Catholic church regards masturbation as a 'gravely disordered action'. Among men masturbation may be seen as a sign of weakness, and there are slang terms for it used as insults.
The Sambia tribe of New Guinea has rites of passage surrounding manhood which involve frequent ejaculation through fellatio. Semen is valued and masturbation is seen as a waste of semen and is therefore frowned upon, even though frequent ejaculation is encouraged. The capacity and need to ejaculate is nurtured for years from an early age through fellatio so that it can be consumed rather than wasted. Semen is ingested for strength and is considered in the same line as mothers' milk.
Other cultures have rites of passage into manhood that culminate in the first ejaculation of a male, usually by the hands of a tribal elder. In some tribes such as the Agta in the Philippines, stimulation of the genitals is encouraged from an early age. Upon puberty, the young male is then paired off with a "wise elder" or "witch doctor" who uses masturbation to build his ability to ejaculate in preparation for a ceremony. The ceremony culminates in a public ejaculation before a celebration. The ejaculate is saved in a wad of animal skin and worn later to help conceive children. In this and other tribes, the measure of manhood is actually associated more with the amount of ejaculate and his need than penis size. Frequent ejaculation through masturbation from an early age fosters frequent ejaculation well into adulthood.
Masturbation marathons have occurred in the U.S. and UK. These events provide a supportive environment where masturbation can be performed openly.
Masturbation may increase fertility during sexual intercourse. In females, it can regulate the conditions of the vagina, cervix and the uterus. This can either increase or decrease the chance of conception. Whether the chance is increased or decreased depends on the timing of the masturbation. This timing is a subconscious decision. If she has intercourse with more than one male, it favors the chances of one or the other male's sperm reaching her egg.
Female masturbation can also protect against cervical infections. It does this by increasing the acidity of the cervical mucus and by moving debris out of the cervix.
The function of masturbation in males is to flush out old sperm with low motility from the male's genital tract. The next ejaculate contains more fresh sperm, which has higher chances of achieving conception during intercourse. If more than one male is having intercourse with a female, the sperm with the highest motility will compete more effectively.
The physical effect of masturbation and having an orgasm or ejaculating is heightened arousal while epinephrine courses through the body, producing a flushed face, shallow breath and post-climactic euphoria.
It is held in many mental health circles that masturbation can relieve depression, stress and lead to a higher sense of self-worth. Masturbation can also be particularly useful in relationships where one partner wants more sex than the other — in which case masturbation provides a balancing effect and thus a more harmonious relationship.
Mutual masturbation, the act by which two or more partners stimulate themselves in the presence of each other, allows a couple to reveal the map to their pleasure centers. Witnessing a partner masturbate is an educational activity to find out the method a partner uses to please themself, allowing each partner to learn exactly how the other enjoys being touched.
In 2003, an Australian research team led by Graham Giles of The Cancer Council Australia concluded that frequent masturbation by males appears to help prevent the development of prostate cancer.