FirstMed Consulting Blog

Masters and Johnson in the 1960s, divided sexual response into four distinct phases: arousal, plateau, orgasm and resolution - each having their individual physical traits.

The arousal phase includes erection (hardening of the normally flaccid penis to permit vaginal penetration) accompanied by testicular vasocongestion (engorgement with blood) and heightened sexual awareness.

The plateau phase is characterised by intensification of these responses, with addition of more generalised body responses, such as increasing heart rate, blood pressure, respiratory rate, and muscle tension – sympathetic nervous system activity that gets us ready for action.

The orgasmic phase includes ejaculation (emptying of sperm and accessory sex gland secretions into the urethra followed by forceful expulsion of semen from the penis) as well as other responses that culminate the mounting sexual responses and are collectively experienced as intense physical pleasure.

The resolution phase returns the genitalia and body systems to their pre-arousal state. During resolution, sympathetic innervation reduces the inflow of blood into the penis, causing the erection to subside. The heart and breathing rates slow down and a period of deep relaxation ensues. Following ejaculation, there is a variable refractory period, and during this time, another erection cannot be achieved. Thus males cannot experience multiple orgasms as females sometimes do.

However, the human sexual response has other components in addition to these physiological phenomena. It also includes emotional, psychological and sociological factors. Masters and Johnson’s model has been elaborated to be more illustrative of the human sexual response by Janssen et al. who constructed the dual-stage information processing model based on experiments on by Beach et al. The sexual response was divided into two main processes: motivation and consummation. Motivation involves a sexual arousal mechanism that determines a male’s sexual reaction to perception of a receptive female. Its main function is to stimulate the male to approach a female and raise his sexual excitement to the threshold necessary for consummatory elements of sexual behaviour: mounting and intromission. Thereafter, the consummatory mechanism controls the thrusting of the hips and ejaculatory elements of the male’s sexual behaviour, integrating the sequence of mounts and intromissions, which amplifies the male’s sexual arousal until ejaculation occurs.

Motivation is triggered by subliminal stimulus (i.e. perception of a receptive female) which is pre-attentively analysed. If the stimulus is deemed desirable, pre-attentive analysis may proceed to subconscious inhibition of mechanisms that restrain the male from approaching the female. Biological and psychological factors influence processing in the limbic system (our emotional centre) which can progress to physical arousal, raising our awareness of sexual stimulation. The male is then driven by sexual desire and responds in context of psychological and sociological circumstances.

Having analysed the nature of the human sexual response, this series of articles will go on to describe psychological and physiological aspects of sex, explain what happens when things go wrong, and explore solutions to sexual problems.