Introductory Psychology: Sex

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lecture 25 from a college level introduction to psychology course taught Fall 2011 by Brian J. Piper, Ph.D. (psy391@gmail.com) at Willamette University, includes Masters & Johnson, Kinsey, neuroanatomy,

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Introductory Psychology: Sex

  1. 1. SexBrian J. Piper, Ph.D.
  2. 2. History• 1524: Pietro Aretino & Marcanonio Raimonbi accompany 16 pornographic engravings with sonnets in I modi• 1923: Sigmund Freud publishes the “The Ego and the Id”• 1948: Alfred Kinsey publishes “Sexual Behavior and the Human Male”• 1957: FDA approves “the pill”• 1957-1992: Masters & Johnson conduct laboratory studies 1915-2001 1894-1956 1925-
  3. 3. Sexual Response Cycle
  4. 4. The Psychobiology of SexMasters and Johnson (1966) describe the human sexual response cycle as consisting of four phases: Phase Physiological Response Genitals become engorged with blood. VaginaExcitement expands secretes lubricant. Penis enlarges. Excitement peaks such as breathing, pulse andPlateau blood pressure. Contractions all over the body. Increase inOrgasm breathing, pulse & blood pressure. Sexual release. Engorged genitals release blood. Male goesResolution through refractory phase. Women resolve slower.
  5. 5. Female Orgasm• Female orgasm (clitoral stimulation) versus rest in heterosexual volunteers (N=12) during PET scanningGeorgiais et al. (2006). European Journal of Neuroscience, 24, 3305-3316.
  6. 6. Female Orgasm• PET scanning [15O]-H2O, subjective report of orgasm, and rectal pressure monitoringGeorgiais et al. (2006). European Journal of Neuroscience, 24, 3305-3316.
  7. 7. Female Orgasm „Le Petit Mort‟• Areas Activated: motor cortex, cerebellum• Areas De-activated: amygdala, prefrontal cortexGeorgiais et al. (2006). European Journal of Neuroscience, 24, 3305-3316.
  8. 8. Male Orgasm • 12 heterosexual males experienced orgasm while completing PET scanning • Activated: cerebellum, thalamus, insula • Deactivated: amygdalaHolstege et al. (2004) J Neuroscience, 23, 9185-9197.
  9. 9. Hormones and Sexual BehaviorSex hormones effect the development of sexual characteristics and (especially in animals) activate sexual behavior. Testosterone Male Testes (Small amounts of estrogen) Ovaries Estrogen Female (Small amounts of Adrenals testosterone)
  10. 10. EstrogenFemale animals “in heat” express peak levels ofestradiol. Female receptivity may be heightened with estradiol injections. Sex hormones may have milder affects on humans than on other animals.
  11. 11. TestosteroneLevels of testosterone vary somewhat in males over a 24 hour period. Castration, which reduces testosterone levels, lowers sexual interest.
  12. 12. Testosterone & AgeLevels of testosterone vary somewhat in males over a 24 hour period. Castration, which reduces testosterone levels, lowers sexual interest.
  13. 13. External Stimuli It is common knowledge that men becomesexually aroused when browsing through erotic material. However, women experience similarheightened arousal under controlled conditions.
  14. 14. Imagined Stimuli Our imagination in our brain can influencesexual arousal and desire. People with spinalcord injuries and no genital sensation can still feel sexual desire.
  15. 15. Adolescent Sexuality When individuals reach adolescence, theirsexual behavior develops. However, there are cultural differences.Sexual promiscuity in modern Western culture is much greater than in Arab countries and other Asian countries.
  16. 16. The Biopsychosocial Aspects of Sex
  17. 17. Sexual OrientationSexual orientation refers to a person’s preference for emotional and sexual relationships withindividuals of the same sex, the other sex, and/or either sex. Homosexual Heterosexual Bisexual
  18. 18. Sexual Orientation StatisticsIn Europe and America, based on many national surveys, homosexuality in men is 3.5% and in women is 1.5%.As members of a minority, homosexuals often strugglewith their sexual orientation (suicide/depression 3X).
  19. 19. Origins of Sexual OrientationHomosexuality is more likely based onbiological factors like differing brain centers,genetics, and parental hormone exposure ratherthan environmental factors.
  20. 20. Neurobiological Basis of Homosexuality?• Levay compared the volume of the interstital nuclei of the anterior hypothalamus (INAH)• His sample (N=41) consisted of: – 19 male homosexuals (19 AIDS+) – 16 male heterosexuals (6 AIDS+) – 6 female heterosexuals (1 AIDS+) 1943-LeVay (1991). Science, 253, 1034-1037.
  21. 21. Animal Homosexuality (1500) Mammals Birds Fish Insects cat barn owl Amazon molly bedbug chimpanzee chicken Bluegill sunfish blowfly dog emu char cockroach elephant King Penguin Jewel fish house fly fox mallard Salmon Monarch butterfly lion raven Ten-spined red ant stickleback raccoon seagull Three-spined Tsetse fly sticklebackBruce Bagemihl (1999) Biological Exuberance: Animal Homosexuality and Natural Diversity
  22. 22. Hypothalamus in Sheep • 8% of rams mount males • Rossi compared the sexually dimorphic nucleus of females, males that prefer females (MPF), males that prefer males (MPM) Females MPF MPM Females MPF MPMRossi et al. (2004). Endocrinology, 145, 478-483.
  23. 23. Hypothalamic Structure • 8% of rams mount males • Rossi compared the sexually dimorphic nucleus of females, males that prefer females (MPF), males that prefer males (MPM) Females MPF MPM Females MPF MPMRossi et al. (2004). Endocrinology, 145, 478-483.
  24. 24. Hypothalamic Function• PET scans were completed while smelling androstadien (AND) versus room air by young Heterosexual Women (HeW), Homosexual Men (HoM), and Heterosexual Men (HeM, N=12/group).Savic et al. (2005). Proceedings of the National Academy of Sciences, 102, 7356-7361.
  25. 25. Hypothalamic Function• PET scans were completed while smelling androstadien (AND) versus room air by young Heterosexual Women (HeW), Homosexual Men (HoM), and Heterosexual Men (HeM, N=12/group).Savic et al. (2005). Proceedings of the National Academy of Sciences, 102, 7356-7361.
  26. 26. Genes & Sexual Orientation A number of reasons suggest that homosexuality may be due to genetic factors.1. Family: Homosexuality seems to run in families.2. Twin studies: Homosexuality is more common in identical twins than fraternal twins.3. Fruit flies: Genetic engineers can genetically manipulate females to act like males during courtship and males to act like females.
  27. 27. Female-Female Behavior • Male fruit flies have a fixed action pattern courtship pattern – Follow female -> Foreleg tap -> Sing song • Fruitless gene is spliced in a sex specific pattern • Females with male fru showed male behavior • VideosDemir & Dickson (2005). Cell, 121, 785-794.
  28. 28. Neurobehavioral Differences • Hetero and homo sexual men and women (N = 35/group) completed a virtual water maze.Rahman & Andersson (2008) Hippocampus, 18, 55-63.
  29. 29. Sexual Orientation: Biology
  30. 30. Changing Attitudes
  31. 31. Contraception1. Ignorance: Canadian teen girls do not have the right ideas about birth control methods.2. Guilt Related to Sexual Activity: Guilt reduces sexual activity, but it also reduces the use of contraceptives.3. Minimal Communication: Many teenagers feel uncomfortable discussing contraceptives.4. Alcohol Use: Those who use alcohol prior to sex are less likely to use contraceptives.5. Mass Media: The media’s portrayal of unsafe extramarital sex decreases the use of contraceptives.
  32. 32. Sexual Problems Men generally suffer from two kinds of sexual problems: premature ejaculation and erectile disorder. Women may suffer from orgasmic disorders. These problems are not due to personality disordersand can be treated through behavior therapy and drugs.
  33. 33. Acquired Immune Deficiency Syndrome• Caused by Human Immunodeficiency Virus• Transmitted via anal & vaginal sex, needles, pregnancy/childbirth• Worldwide (UNAIDS, 2009): – 60.0 million infected – 25 million dead – 14 million orphaned children 1959-(1991)-
  34. 34. Summary• Sexual Response Cycle• Biopsychosocial factors• Individual Differences in Orientation – Genetic – Endocrine – Neurobiological – Behavioral

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