6K - views

Module 15 Human Sexuality

Josef F. . Steufer. /Getty Images. Asexuality. . is . having no sexual attraction to others.. Sex . hormones . are one of the forces that drive sexual . behavior. .. Testosterone: . Most important male sex hormone.

Embed :
Presentation Download Link

Download Presentation - The PPT/PDF document "Module 15 Human Sexuality" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.

Module 15 Human Sexuality

Presentation on theme: "Module 15 Human Sexuality"— Presentation transcript:


Module 15

Human Sexuality

Josef F.


/Getty ImagesSlide2


is having no sexual attraction to others.


hormones are one of the forces that drive sexual behavior.Testosterone: Most important male sex hormoneIn both males and females, but the additional testosterone in males stimulates growth of the male sex organs during fetal period, and development of the male sex characteristics during pubertyEstrogens: The estrogens sex hormones, such as estradiol, are secreted in greater amounts by females than by males and contribute to female sex characteristics In nonhuman female mammals, estrogen levels peak during ovulation, promoting sexual receptivity


Human Sexuality: The Physiology of Sex

Hormones and Sexual BehaviorSlide3

Human Sexuality: The

Physiology of SexHormones and Sexual Behavior

Large hormonal surges or declines tend to occur at two predictable points in life span

Pubertal stage surge triggers development of sex characteristics and sexual interestIn later life, hormone levels fall, with women experiencing menopause and men a more gradual changeA third point sometimes occursFor some, surgery or drugs may cause hormonal shiftsSlide4

Human Sexuality: The

Physiology of SexThe Sexual Response Cycle


: WHAT IS THE HUMAN SEXUAL RESPONSE CYCLE, AND HOW DO SEXUAL DYSFUNCTIONS AND PARAPHILIAS DIFFER?The sexual response cycle identifies four stages of sexual responding as identified by William Masters and Virginia Johnson (1966):ExcitementPlateauOrgasmResolutionSlide5





The Sexual Response Cycle (Masters and Johnson)

Human Sexuality:





The Sexual Response CycleSlide6

Human Sexuality:

The Physiology of Sex

Sexual Dysfunctions and Paraphilias

Sexual dysfunctionsImpair sexual arousal or functioningOften involve sexual motivation, especially sexual motivation and arousalInclude erectile disorder and premature ejaculation (males)Include female orgasmic disorder and female sexual interest/arousal disorder (females) Sometimes involve paraphilias (sexual desire directed in unusual ways; e.g., pedophilia, exhibitionism)Slide7


Sexuality: The Physiology of Sex Sexual Dysfunctions and Paraphilias

Sexual dysfunction

Problem that consistently impairs sexual arousal or functioningErectile disorderInability to develop or maintain an erection due to insufficient bloodflow to the penisPremature ejaculationSexual climax that occurs before the man or his partner wishesSlide8


Sexuality: The Physiology of Sex Sexual Dysfunctions and Paraphilias

Female orgasmic disorder

Distress due to infrequently or never experiencing orgasmParaphiliasSexual arousal from fantasies, behaviors, or urges involving nonhuman objects, the suffering of self or others, and/or non-consenting personsSlide9


Sexuality: The Physiology of Sex Sexual Dysfunctions and Paraphilias

American Psychological Association (2013)

Only classifies people as disordered who experience sexual desire in unusual ways if:Person experiences distress from unusual sexual interest orIt entails harm or risk of harm to othersParaphilias include necrophilia, exhibitionism, and pedophiliaSlide10

Human Sexuality: The

Physiology of SexSexually Transmitted Infections


: HOW CAN SEXUALLY TRANSMITTED INFECTIONS BE PREVENTED?Sexually transmitted infection (STI)Also called sexually transmitted disease (STD)Every day, more than 1 million people worldwide acquire an STIAIDS (acquired immune deficiency syndrome)Is life-threatening, sexually transmitted infectionCaused by the human immunodeficiency virus (HIV)Depletes immune system and leaves person vulnerable to infectionsSlide11


Sexuality: The Physiology of Sex Sexually Transmitted Infections


report: 14- to 19-year-old U.S. females found 39.5 percent had STIs.Condom use effectiveness varies by infection (80 percent effectiveness against transmission of HIV when used with infected partner; less effective with skin-to-skin STIs such as herpes).Significant link between oral sex and STIs, such as HPV; most HPV infections can now be prevented with a vaccination administered before sexual contact. Worldwide, women’s AIDs rates are increasing fastest, partly because the virus is passed from man to woman much more often than woman to man.Slide12




Levels of Analysis for Sexual MotivationHuman Sexuality: The Psychology of SexSlide13

Human Sexuality: The

Psychology of SexExternal Stimuli


sophisticated brain allows us to experience sexual arousal both from what is real and from what is imaginedExternal stimuliPeople may find sexual arousal from erotic materials either pleasing or disturbing; repeated exposure often habituates emotional responseMen tend to be more aroused when erotic material aligns with personal sexual interestPornography may increase rape acceptance, and decrease evaluation of and sexual satisfaction with own partnerSlide14

Human Sexuality: The

Psychology of SexImagined Stimuli

Imagined stimuli

Sexual desire and arousal can be imagined; our brain has been said to be our most significant sex organPeople with spinal-cord injury reported feeling sexual desire95 percent of people report having sexual fantasiesMale fantasies tend to be more frequent, more physical, and less romantic than those of womenSlide15

Human Sexuality: The

Psychology of SexTeen Pregnancy


: WHAT FACTORS INFLUENCE TEENAGERS’ SEXUAL BEHAVIORS AND USE OF CONTRACEPTIVES?Compared with European teens, American teens have higher rates of STIs and teen pregnancyEnvironmental factors that influence a higher teen pregnancy rate: Minimal communication about birth controlGuilt related to sexual activityAlcohol useMass media norms of unprotected promiscuity; media help write the social scripts that affect our perceptions and actionsSlide16

Human Sexuality: The Psychology of Sex

Teen Pregnancy

Later sex may pay emotional dividends, with those who had later first sex reporting greater relationship satisfaction

Factors that predict sexual restraint:High intelligenceReligious engagementFather presenceParticipation in service learning programsSlide17

Human Sexuality

Sexual Orientation


: WHAT HAS RESEARCH TAUGHT US ABOUT SEXUAL ORIENTATION?Sexual orientation is our enduring sexual attraction towardmembers of one’s own sex (homosexual orientation)the other sex (heterosexual orientation)or both sexes (bisexual orientation)In all cultures, heterosexuality has prevailed but homosexuality has existed. Where same-sex relationships are illegal, the prevalence of people who are lesbian, gay, or bisexual is no different.Slide18

Human Sexuality

Sexual Orientation: The Numbers

Survey results vary by survey methods and population; less open response in less tolerant places

Exclusively homosexual: 3 to 4 percent in men and 2 percent in womenActively bisexual: Reported by fewer than 1 percent—for example, 12 out of 7076 people in a Dutch survey5 percent of men and 13 percent of women in U.S. report some same-sex sexual contact during their livesAPA (2009) reports efforts to change sexual orientation are unlikely to be successful and involve some risk of harmWomen’s sexual orientation tends to be less strongly felt and potentially more fluid; sexual activity level also varies moreSlide19

Human Sexuality: Sexual

OrientationOrigins of Sexual Orientation


is not linked with problems in parent-child relationships, does not involve a fear or hatred of the other sex, and isn’t significantly linked to childhood sexual victimization There is a lack of evidence for environmental causes of homosexualityInstead, homosexuality seems to have biological influences, as investigated in studies of same-sex behavior in other species, gay-straight brain differences, genetic influences, and prenatal influencesSlide20

Human Sexuality: Sexual

OrientationOrigins of Sexual Orientation


attraction in other speciesSame-sex behavior has been observed in several hundred species (swans, penguins, grizzlies, gorillas, monkeys, flamingos, and owls).Gay-straight brain differencesGay-straight brain differences where one hypothalamic cell cluster is smaller in women and gay men than in straight menAnterior commissure is larger in gay men than in straight men.Gay men’s hypothalamus reacts as do straight women’s to the smell of sex-related hormones.Slide21

Human Sexuality: Sexual

OrientationOrigins of Sexual Orientation

Genetic influences

Shared sexual orientation is higher among identical twins than among fraternal twins.Sexual attraction in fruit flies can be genetically manipulated.Male homosexuality often appears to be transmitted from the mother’s side of the family.Slide22

Human Sexuality: Sexual

OrientationOrigins of Sexual Orientation


InfluencesAltered prenatal hormone exposure may lead to homosexuality in humans and other animals.Men with several older biological brothers are more likely to be gay, possibly due to a maternal immune-system reaction.The consistency of the brain, genetic, and prenatal findings clearly leads to a biological explanation of sexual orientation.Slide23

The fraternal birth-order effect

Human Sexuality:


OrientationOrigins of Sexual OrientationSlide24

spatial abilities

fingerprint ridge counts

auditory system development


occupational preferences

relative finger lengths

gender nonconformity

age of onset of puberty in males

birth size and weight

sleep length

physical aggression

walking style

Research indicates that homosexuals and heterosexuals differ in the following traits

Human Sexuality:



Origins of

Sexual Orientation Gay-Straight Trait DifferencesSlide25

Why might natural selection have resulted in greater male promiscuity?

Cross-culturally, men think more than women about sex, and men are more likely to think that casual sex is acceptable.



An Evolutionary Explanation of Human Sexuality

: Male-Female


in SexualitySlide26


with lesbians, gay men (like straight men) report more interest in uncommitted sex, more responsiveness to visual sexual stimuli, and more concern with their partner’s physical attractiveness.

Gay male couples report having sex more often than do lesbian


Men who had the trait of promiscuity were more likely to have their genes continue, and even spread, in the next generation



is little cost to





For women, a trait of promiscuity would not greatly increase the number of babies, and it would have greater survival costs. Pregnancy was often life-threatening.

An Evolutionary Explanation of Human Sexuality

: Male-Female

Differences in SexualitySlide27

Why might natural selection have resulted in mating preferences?


choices optimized the chance of producing offspring.

Female choices

optimized offspring


Men chose widely; women chose wisely!

Men prefer women with signs of future fertility (narrow waist and fuller figure; age of peak fertility). Women prefer men with loyal behavior and physical/social power and resources.

An Evolutionary Explanation of Human


Natural Selection and Mating PreferencesSlide28

Human Sexuality

Critiquing the Evolutionary Perspective


: WHAT ARE THE KEY CRITICISMS OF EVOLUTIONARY EXPLANATIONS OF HUMAN SEXUALITY, AND HOW DO EVOLUTIONARY PSYCHOLOGISTS RESPOND?Most psychologists agree that natural selection prepares humans for survival and reproduction. But critics of evolutionary psychology research note these limitations:Evolutionary psychology starts with and effect and works backward to explain what happenedMore immediate explanations better understood through social learning theory (including social scripts) than decisions made by our distant ancestorsSocial consequences of evolutionary explanation are problematic

Some traits and behaviors are difficult to explain by natural selectionSlide29

Human Sexuality

Social Influences on Human Sexuality


: WHAT ROLE DO SOCIAL FACTORS PLAY IN OUR SEXUALITY, AND HOW DO NATURE, NURTURE, AND OUR OWN CHOICES INFLUENCE GENDER ROLES AND SEXUALITY?Human sexuality research does not aim to define personal meaning of sex, but one significance of such intimacy is its expression of our profoundly social nature.For both men and women, but especially for women, orgasm occurs more often when sex happens in a committed relationship rather than a sexual hookup.Sex is a socially significant act. Achieving orgasm alone is less satisfying, and with much less of a surge in the prolactin hormone associated with sexual satisfaction and satiety, than after sex with a loved one.Thanks to overlapping brain reward areas, sexual desire and love feed each other.Slide30

Reflections on the Nature and Nurture of Sex, Gender, and Sexuality

Our ancestral history helped form us as a species; where there is variation, natural selection, and heredity, there will be evolution. But our culture and experiences also form us.


nature is formed by:Our genesOur culture and experiencesIn many modern cultures, gender roles are merging. There have been swift changes in gender roles and sexual attitudes since 1960; biology does not fix gender roles.We can’t excuse our failings by blaming them solely on bad genes or bad influences. In reality, we are both the creatures and creators of our worlds.