Masters and Johnson
Overview
The Masters and Johnson research team, composed of William H. Masters
William H. Masters
William Howell Masters was an American gynecologist, best known as the senior member of the Masters and Johnson sexuality research team...

 and Virginia E. Johnson
Virginia E. Johnson
Virginia Eshelman Johnson is a former American sexologist and psychologist, best known as the junior member of the Masters and Johnson sexuality research team...

, pioneered research into the nature of human sexual response
Human sexual response cycle
The human sexual response cycle is a four-stage model of physiological responses during sexual stimulation. These phases, in order of their occurrence, are the excitement phase, plateau phase, orgasmic phase, and resolution phase. The term was coined by William H. Masters and Virginia E...

 and the diagnosis and treatment of sexual disorders and dysfunctions from 1957 until the 1990s.

Their work began in the Department of Obstetrics and Gynecology at Washington University in St. Louis
Washington University in St. Louis
Washington University in St. Louis is a private research university located in suburban St. Louis, Missouri. Founded in 1853, and named for George Washington, the university has students and faculty from all fifty U.S. states and more than 110 nations...

 and was continued at the independent not-for-profit research institution they founded in St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

 in 1964, originally called the Reproductive Biology Research Foundation and renamed the Masters & Johnson Institute in 1978.

In the initial phase of their studies, from 1957 until 1965, they recorded some of the first laboratory data on the anatomy and physiology of human sexual response based on direct observation of 382 women and 312 men in what they conservatively estimated to be "10,000 complete cycles of sexual response." Their findings, particularly on the nature of female sexual arousal
Sexual arousal
Sexual arousal, or sexual excitement, is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are many potential stimuli, both physical or mental, which can cause...

 (for example, describing the mechanisms of vaginal lubrication
Vaginal lubrication
Vaginal lubrication is a lubricating fluid that is naturally produced in a woman's vagina. Vaginal lubrication or moistness is present at all times, but production increases significantly during a woman's sexual arousal in anticipation of sexual intercourse...

 and debunking the earlier widely-held notion that vaginal lubrication originated from the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...

) and orgasm
Orgasm
Orgasm is the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure...

 (showing that the physiology of orgasmic response was identical whether stimulation was clitoral or vaginal, and proving that some women were capable of being multiorgasmic), dispelled many long standing misconceptions.

They jointly wrote two classic texts in the field, Human Sexual Response and Human Sexual Inadequacy, published in 1966 and 1970 respectively.
 
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