3.5 Problem: Sex
Hock: The Physiology of Human Sexual Responding
Biology, Psychology, and Human Sexual Responding
For humans, many aspects of our sexual responses are based on biology, but not
always. Our desire to engage in sex is not clearly linked to female’s fertility cycle to
ensure reproduction, and in gay/lesbian sex this consideration is nonexistent. Humans’
reasons for engaging in sexual behaviour is more varied because psychological
processes play a role as great as, or arguably greater than, biology
Why do humans become sexually aroused?
Could be to feel pleasure, to give pleasure, express feelings of closeness & love,
relieve stress, feeling valued by another person, expressing how much another person
is valued, feeling more dominant/submissive, etc. These are psychological reasons,
they are fundamentally human
Masters & Johnson: The Excitement-Plateau-Orgasm Resolution (EPOR) Model
To explain how our bodies change during sexual stimulation, Masters & Johnson
divided the process into 4 phases of sexual response:
Excitement, Plateau, Orgasm and Resolution – the EPOR model
These 4 phases aren’t to be seen as four separate and distinct events; they are ‘a four-
part division of the sexual response cycle’
It’s impossible to identify exactly when excitement stops and plateau begins, or
precise moment orgasm starts/ends
Female cycle tends to be more varied than that of the male.
Men generally progress fairly predictably
Excitement Phase = first phase in
through the 4 stages and require some time
EPOR model, where first physical
between orgasms, called a refractory
changes of sexual arousal occur
period, before another orgasm.
Women may follow similar pattern, or may
Plateau phase = second phase in
experience multiple orgasms without a
EPOR model, where sexual arousal
refractory period, or may progress from
levels off (reaches plateau) and
excitement to plateau to resolution without
remains at elevated level of
experiencing an orgasm
excitement
Aphrodisiac = mythical substances
Excitement & Plateau: The First 2 Stages
that are thought to enhance sexual
arousal & desire
Other researchers have argued that plateau
is probably just an extension of excitement
Vasocongestion = swelling of
Early arousal responses can occur from any
erectile tissues due to increased
type of pleasurable sexual stimulation, e.g.,
blood flow during sexual arousal
kissing, erotic touching, sexual fantasy,
sexually arousing visual materials,
Sex flush = darkening/reddening of
masturbation, or intercourse
the skin of the chest area that occurs
During excitement, for both sexes, blood
in some people during sexual
begins to circulate into erectile structures
arousal
throughout the body, causing them to
expand & enlarge: vasocongestion
, Sex flush/reddening of the skin/chest/abdomen may occur, nipples become erect,
breathing becomes heavier & faster, heart rate increases, voluntary muscles tense in a
process called myotonia
For men, first and most obvious sign of sexual excitement starts in erection of the
penis. At this early stage, man may not achieve full erection, erection is easily lost if
stimulation ceases/some sort of distraction occurs, but also can be easily regained.
Anxiety over losing your erection can become self-fulfilling prophecy, anxiety could
prevent return of erection
For women, first and most obvious sign of sexual excitement is erection of clitoris,
but most perceptible sign is vaginal lubrication
Leveling off of arousal seems to occur at some point in excitement phase, where
people continue to be very aroused, but don’t appear to be experiencing much
additional elevation in their level of arousal – this is plateau phase
Plateau phase: for both sexes, erectile tissues are now fully engorged with blood.
Respiration, heart rate, blood pressure and muscle tension are all at high levels as
orgasm approaches. Sexual flush on skin spreads, darkens
Orgasm Phase
Climax of sexual arousal
Shortest phase of the 4 phases, usually lasting 15 seconds
Women tend to require longer period of stimulation than men do to achieve orgasm
with a partner, majority don’t experience orgasm through heterosexual intercourse
exclusively
Women are capable of additional orgasms with continued stimulation without a
refractory period = multiple orgasms
Factors influencing intensity & duration of orgasms: length of arousal prior to
orgasm, length of time since previous orgasm, alcohol/drug use, feelings of comfort &
intimacy with partner
People who have never experienced orgasm = preorgasmic (more common in women
than men)
For men & women, as orgasm approaches: respiration increases, pulse & blood
pressure continue to rise. Sexual flush may spread over more of the body, loss of
control over some voluntary muscles results in muscle contractions & spasms,
especially in hands & feet
For men, usually includes ejaculation
Ejaculation occurs in 2 stages:
1) Emission (subjective sensation that ejaculation has begun, nothing can stop it).
Sensation of having reached ‘point of no return’ is called moment of ejaculatory
inevitability
2) Expulsion: contractions push semen out of the penis
Although orgasms are great, they should not be the goal of sexual interactions.
Focusing on orgasm as main objective of sex may detract, rather than enhance,
intimate experience
Health Benefits of Orgasm
, Health Benefit Research Findings
General Health Orgasm once/twice a week strengthens
immune system’s ability to resist flu &
other viruses
Pain Relief Orgasm’s release of hormones & muscle
contractions can help relieve pain of
menstrual cramps, raise pain tolerance
Lower cancer rate Men who have more than 5 ejaculations
per week during their 20s have
significantly lower rate of prostate
cancer later in life
Longer life Men who have 2 or more orgasms per
week live significantly longer than men
who have fewer
Greater feelings of intimacy Oxytocin (hormone that may play a role
in feelings of love & intimacy) increases
5x at orgasm
Less heart disease Men who have at least 3 orgasms per
week are 50% less likely to die of heart
disease
Better sleep Dopamine, released during orgasm,
triggers a stress-reducing, sleep-inducing
response that may last up to 2 hours
Younger appearance People who have frequent orgasms in
conjunction with ‘lovemaking’ are
judged to look younger than their less
sexually active counterparts
Resolution Phase
Also referred to as detumescence (‘reduction in swelling’)
Completion of the cycle, body returns to its sexually non-aroused state
Typically happens rapidly after orgasm, but takes longer if orgasm hasn’t happened
For men & women: heart rate, blood pressure, and muscle tension drop quickly. Body
may be covered with sweat. Sexual flush fades. Feelings of relaxation, warmth,
contentment, sleepiness
If woman receives additional stimulation following orgasm, she may be capable of
returning to plateau phase and have additional orgasms, without entering resolution
phase/refractory period
When men enter resolution phase, they must take a break before becoming aroused
again (men are not capable of multiple orgasms). This is called the refractory period
Depending on a number of factors (fatigue, frequency of orgasms, age), the refractory
period in men may last anywhere from a few minutes to 24 hours or more
Criticisms of Master & Johnson’s EPOR Model
Hock: The Physiology of Human Sexual Responding
Biology, Psychology, and Human Sexual Responding
For humans, many aspects of our sexual responses are based on biology, but not
always. Our desire to engage in sex is not clearly linked to female’s fertility cycle to
ensure reproduction, and in gay/lesbian sex this consideration is nonexistent. Humans’
reasons for engaging in sexual behaviour is more varied because psychological
processes play a role as great as, or arguably greater than, biology
Why do humans become sexually aroused?
Could be to feel pleasure, to give pleasure, express feelings of closeness & love,
relieve stress, feeling valued by another person, expressing how much another person
is valued, feeling more dominant/submissive, etc. These are psychological reasons,
they are fundamentally human
Masters & Johnson: The Excitement-Plateau-Orgasm Resolution (EPOR) Model
To explain how our bodies change during sexual stimulation, Masters & Johnson
divided the process into 4 phases of sexual response:
Excitement, Plateau, Orgasm and Resolution – the EPOR model
These 4 phases aren’t to be seen as four separate and distinct events; they are ‘a four-
part division of the sexual response cycle’
It’s impossible to identify exactly when excitement stops and plateau begins, or
precise moment orgasm starts/ends
Female cycle tends to be more varied than that of the male.
Men generally progress fairly predictably
Excitement Phase = first phase in
through the 4 stages and require some time
EPOR model, where first physical
between orgasms, called a refractory
changes of sexual arousal occur
period, before another orgasm.
Women may follow similar pattern, or may
Plateau phase = second phase in
experience multiple orgasms without a
EPOR model, where sexual arousal
refractory period, or may progress from
levels off (reaches plateau) and
excitement to plateau to resolution without
remains at elevated level of
experiencing an orgasm
excitement
Aphrodisiac = mythical substances
Excitement & Plateau: The First 2 Stages
that are thought to enhance sexual
arousal & desire
Other researchers have argued that plateau
is probably just an extension of excitement
Vasocongestion = swelling of
Early arousal responses can occur from any
erectile tissues due to increased
type of pleasurable sexual stimulation, e.g.,
blood flow during sexual arousal
kissing, erotic touching, sexual fantasy,
sexually arousing visual materials,
Sex flush = darkening/reddening of
masturbation, or intercourse
the skin of the chest area that occurs
During excitement, for both sexes, blood
in some people during sexual
begins to circulate into erectile structures
arousal
throughout the body, causing them to
expand & enlarge: vasocongestion
, Sex flush/reddening of the skin/chest/abdomen may occur, nipples become erect,
breathing becomes heavier & faster, heart rate increases, voluntary muscles tense in a
process called myotonia
For men, first and most obvious sign of sexual excitement starts in erection of the
penis. At this early stage, man may not achieve full erection, erection is easily lost if
stimulation ceases/some sort of distraction occurs, but also can be easily regained.
Anxiety over losing your erection can become self-fulfilling prophecy, anxiety could
prevent return of erection
For women, first and most obvious sign of sexual excitement is erection of clitoris,
but most perceptible sign is vaginal lubrication
Leveling off of arousal seems to occur at some point in excitement phase, where
people continue to be very aroused, but don’t appear to be experiencing much
additional elevation in their level of arousal – this is plateau phase
Plateau phase: for both sexes, erectile tissues are now fully engorged with blood.
Respiration, heart rate, blood pressure and muscle tension are all at high levels as
orgasm approaches. Sexual flush on skin spreads, darkens
Orgasm Phase
Climax of sexual arousal
Shortest phase of the 4 phases, usually lasting 15 seconds
Women tend to require longer period of stimulation than men do to achieve orgasm
with a partner, majority don’t experience orgasm through heterosexual intercourse
exclusively
Women are capable of additional orgasms with continued stimulation without a
refractory period = multiple orgasms
Factors influencing intensity & duration of orgasms: length of arousal prior to
orgasm, length of time since previous orgasm, alcohol/drug use, feelings of comfort &
intimacy with partner
People who have never experienced orgasm = preorgasmic (more common in women
than men)
For men & women, as orgasm approaches: respiration increases, pulse & blood
pressure continue to rise. Sexual flush may spread over more of the body, loss of
control over some voluntary muscles results in muscle contractions & spasms,
especially in hands & feet
For men, usually includes ejaculation
Ejaculation occurs in 2 stages:
1) Emission (subjective sensation that ejaculation has begun, nothing can stop it).
Sensation of having reached ‘point of no return’ is called moment of ejaculatory
inevitability
2) Expulsion: contractions push semen out of the penis
Although orgasms are great, they should not be the goal of sexual interactions.
Focusing on orgasm as main objective of sex may detract, rather than enhance,
intimate experience
Health Benefits of Orgasm
, Health Benefit Research Findings
General Health Orgasm once/twice a week strengthens
immune system’s ability to resist flu &
other viruses
Pain Relief Orgasm’s release of hormones & muscle
contractions can help relieve pain of
menstrual cramps, raise pain tolerance
Lower cancer rate Men who have more than 5 ejaculations
per week during their 20s have
significantly lower rate of prostate
cancer later in life
Longer life Men who have 2 or more orgasms per
week live significantly longer than men
who have fewer
Greater feelings of intimacy Oxytocin (hormone that may play a role
in feelings of love & intimacy) increases
5x at orgasm
Less heart disease Men who have at least 3 orgasms per
week are 50% less likely to die of heart
disease
Better sleep Dopamine, released during orgasm,
triggers a stress-reducing, sleep-inducing
response that may last up to 2 hours
Younger appearance People who have frequent orgasms in
conjunction with ‘lovemaking’ are
judged to look younger than their less
sexually active counterparts
Resolution Phase
Also referred to as detumescence (‘reduction in swelling’)
Completion of the cycle, body returns to its sexually non-aroused state
Typically happens rapidly after orgasm, but takes longer if orgasm hasn’t happened
For men & women: heart rate, blood pressure, and muscle tension drop quickly. Body
may be covered with sweat. Sexual flush fades. Feelings of relaxation, warmth,
contentment, sleepiness
If woman receives additional stimulation following orgasm, she may be capable of
returning to plateau phase and have additional orgasms, without entering resolution
phase/refractory period
When men enter resolution phase, they must take a break before becoming aroused
again (men are not capable of multiple orgasms). This is called the refractory period
Depending on a number of factors (fatigue, frequency of orgasms, age), the refractory
period in men may last anywhere from a few minutes to 24 hours or more
Criticisms of Master & Johnson’s EPOR Model
