Editing Masters and Johnson (section)

==Four-stage model of the sexual response==
{{main|Human sexual response cycle}}
One of the most enduring and important aspects of their work has been the four stage model of sexual response, which they described as the human sexual response cycle<ref name="FFWHC"/><ref name="Archer, Lloyd"/> and defined as:
*[[Sexual arousal|Excitement phase]] (initial arousal)
*[[Plateau phase]] (at full arousal, but not yet at orgasm)
*[[Orgasm]]
*[[Refractory period (sex)|Resolution phase]] (after orgasm)

Their model shows no difference between [[Sigmund Freud]]'s purported categories of "[[vagina]]l orgasm" and "[[Clitoris|clitoral]] orgasm": the physiological response was identical, even if the stimulation was in a different place.<ref name="FFWHC"/><ref name="Archer, Lloyd"/>

Masters and Johnson's findings also revealed that men undergo a [[refractory period (sex)|refractory period]] following orgasm during which they are not able to [[Ejaculation|ejaculate]] again, whereas there is no refractory period in women: this makes women capable of multiple orgasm.<ref name="FFWHC"/><ref name="Archer, Lloyd"/> They also were the first to describe the phenomenon of the rhythmic contractions of orgasm in both sexes occurring initially in 0.8 second intervals and then gradually slowing in both speed and intensity.