Motivation and emotion/Book/2011/Sexual motivation

Sexual motivation:
What drives sexual behaviour?
This page is part of the Motivation and emotion book. See also: Guidelines.

Introduction

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Most theorists[who?] refer to motivation as a need or desire that gives behaviour its energy and initiates direction (Reeve, 2009). Therefore, sexual motivation is the drive or force that creates our sexual interest at any given time.

Human motivation to engage in sexual behaviour is due to a complex relationship among several factors such as a social or cultural context, context of an ongoing romantic relationship etc (Meston & Buss, 2007). Unlike other basic drives, sex does not motivate to fulfill a basic biological need, however both biological and psychological factors influence sexual drive. Many assume the main motive to engage in sexual activities is to reproduce, however theoretical perspectives show that it is not one motive that can explain sexual motivation (Meston & Buss, 2007). Individuals are forced[improve clarity] to seek out their desires through sexual activity with another individual (either the same or opposite sex) or through self-gratification.

This chapter focuses on psychological understandings of sexual motivation. The chapter will explore research studies that have been conducted in the area of human sexual behaviour, historical perspectives, the human sexual response cycle, different factors in sexual motivation, gender differences, the role of pheromones, how to pursue sexual motivation safely, and research limitations in sexual motivation.

Historical views

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Evolutionary perspective

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Evolutionary theory in sexual motivation focuses on the gender differences between males and females. Robert Trivers (1974) proposed the theory of parent-offspring conflict, which is the idea that men and women make different parental investments in order to produce offspring. From a biological view, men invest only energy required for sexual intercourse to produce sperm, whereas women invest time throughout the course of pregnancy and many more through breastfeeding (Buss & Schmitt, 1993).

Males have the potential to produce unlimited offspring. Men tend to choose young and attractive partners to ensure reliable fertility, as women’s fertility decline with age (Buss, 1995). Women are highly discriminating and require partners who are willing to commit to her and the protection of her child. Women also choose partners that have the most access to material resources to ensure security (Buss & Schmitt, 1993).

Evolutionary theorist have predicted that men have concerns about their partners sexual infidelity as they can never be 100% certain that they are the fathers of their partners offspring (Buss & Schmitt, 1993). Women on the other hand are concerned about their partner’s emotional infidelity, as they are unsure whether their partners will provide for their offspring (Buss & Schmitt, 1993).

Robert Baker (1995) proposed the idea of sperm competition. According to this theory, a man who suspects his partner may have been sexually disloyal seeks to compete with the sperm of the competing male (Meston & Buss, 2007). The man pushes for harder and longer sexual encounters and is motivated to have sex multiple times[factual?]. Women being unfaithful to their partner enjoy greater sexual motivation, however may reduce the sperm of this partner leaving limited reproduction of rival women (Meston & Buss, 2007)[improve clarity].

Kinseys landmark sex surveys

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Kinsey Institute for Sex Research translation staff

Alfred Kinsey (1953) was one of the first researchers to conduct a study of human sexual behaviour. In the 1940’s and 1950’s he and his colleagues interviewed around 18,000 American males and females about their sexual behaviour and attitudes. Kinsey and his colleagues wanted to gain trust and respect from their interviewees. His approach to gathering data was through mutual understandings with each candidate hoping that in return he will receive honesty in their answers to uncover the true nature of their sexual activities.

The survey reports about human sexuality caused disagreement at the time as the social attitudes and topics in research were unmentionable. Results indicated high levels of masturbation and premarital sex in the 1940s[factual?]. Kinsey later published two books known as the Kinsey Reports on sexual behaviour. Sexual Behaviour in the Human Male (Kinsey, Pomeroy & Martin, 1948) provided eye-openers about male masturbation, sexual activity and homosexuality. Sexual Behaviour in the Human Female (Kinsey, Pomeroy, Martin & Gebhard, 1953) contained exposures[improve clarity] about women’s masturbatory practices, premarital sex and orgasmic experiences (Brown & Fee, 2003). Many criticised Kinsey’s studies, as the sample consisted of a majority of well-educated white individuals. His methods used to gather data were also questionable, as they[who?] believe it may have been misleading as face-to-face interviews were conducted.

Female and male sexual response cycle

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Masters and Johnson four phase model

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Excitement Phase
(Increased feeling of physiological arousal)
Plateau Phase
(The sexual tension continues, which eventually leads to an orgasm)
MEN: penis becomes erect and testes swell
WOMEN: clitoris swells; vaginal lubrication begins; nipples harden
MEN: small amounts of seminal fluid are released from the penis
WOMEN: clitoris becomes sensitive and retracts
Orgasmic Phase
(The peak sensation of pleasure)
Resolution Phase
(The body returns back to normal levels)
MEN: ejaculate seminal fluid and contractions occur in the base
of the penis
WOMEN: muscles of the vagina and uterus contract
MEN: enter the refractory period where he is unable to reach orgasm again

WOMEN: some are able to return to the orgasm phase and may experience
multiple orgasms

William Masters and Virginia Johnson conducted influential studies on sexual behaviours in the 1960s. Their research-involved participants that agreed to either masturbate or have sexual intercourse in a laboratory so that physiological factors could be measured (Masters & Johnson, 1966).

The results of these studies led to the sexual response cycle. This refers to the physical and emotional changes that occur as a person becomes sexually aroused or participates in sexual activities. The sexual response cycle has four phases: the excitement phase, plateau phase, orgasmic phase and the resolution phase (Masters & Johnson, 1966). Results indicated slight variations in the duration and intensity of different phases.

Masters and Johnson faced problems within the scientific communities as the sample only included people who were willing and able to perform sexual activities in a laboratory setting. They also failed to acknowledge individual differences in sexual responses such as sexual experience, age etc.

Kaplan's three phase model

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Desire Phase Vasocongestive Phase Orgasmic-Release Phase
Psychological components of sexual desire

Physical sensations of sexual desire
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Physical stimulation in the pelvic region

Psychological stimulation in the pelvic region

Increased muscle tension and heart rate
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Return to pre-aroused state

Release of muscle tension

Helen Kaplan (1979) proposed an idea that was not mentioned by Masters and Johnson (1966): sexual desire. Sexual desire refers to an individual’s experience of anticipation to have a sexual arousal. Kaplan believed that individuals experience psychological and physiological arousal and she was not satisfied that the sexual response cycle could explain sexual dysfunctions (Kaplan, 1979). Kaplan’s three-phase model included the desire phase, vasocongestive phase (excitement phase) and orgasmic-release phase.

Masters and Johnson’s model incorporates the excitement and orgasm phases; therefore the main difference is the desire phase. Stimulation of the brain system and physiological mechanisms occur in the desire phase. Kaplan believes[grammar?] sexual dysfunction falls into one of these three categories, therefore the psychological desires, along with physical sensations produce the drive that can explain sexual dysfunctions (Kaplan, 1979).

Factors in sexual motivation

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Physiology

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Physiological Factors in Sexual Motivation

Physiological factors, in particular hormones are an important factor of human sexual motivation. Both men and women produce estrogens, progestins and androgens (Leger, 1992). Hormone levels are almost directly linked with sexual behaviour, however in humans they are also related to sexual desire (Fisher, 1993).

To maintain the usual of sexual motivation for men, a minimum level of testosterone is essential (Ledger, 1992). If testosterone levels fall below this level, sexual motivation is greatly reduced. Results in sexual motivation in women have proved to be unreliable even though slight correlations between hormones and sexual desire have been acknowledged. Other factors, other than hormones may also determine whether individuals actually engaged in sexual activities even if they have been prepared for action (Hokanson, 1969).

Odour and sense of smell are another important physiological factor in sexual motivation. Kohl and Francoeur (1995) conducted reviews of numerous studies of menstrual cycles of women and the influence of hormone-scented masks on individuals’ ratings of others and concluded that odours are another influence of human sexual behaviour.

Psychological

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Erotic Stimuli Desires Cultural Context
External Erotic Stimuli:
sexually exciting material that is read, heard or seen

Internal Erotic Stimuli:
thoughts, fantasies and memories of past sexual experiences
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Procreation

Express love

Physical enjoyment

Cope with difficult situations

Peer pressure
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Sexual scripts that allows a person to judge
the appropriate sexual behaviour for a given situation.

Sexual Orientation

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Chart of Sexual Orientations

Sexual orientation refers to the gender (i.e. male or female) to which a person is attracted (Wood & Wood 1996). Researchers have many different opinions regarding how much biological and environmental factors contribute to sexual orientation.

Heterosexuals are people who are attracted to members of the opposite sex (e.g. males attracted to females). Homosexuals are people that are attracted to people of the same sex. Males attracted to other males are referred to as gay; females attracted to other females are referred to as lesbians. Bisexuals are people that are attracted to members of both sexes (e.g. males being attracted to both males and females). Asexual's are people who do not experience sexual attraction to either gender and are not constrained to form sexual relationships.

Most researchers believe sexual orientation is combined of multiple factors (LeVay, 1995). Studies also indicate that quite a small percentage of individuals openly call themselves homosexual (Kinsey, 1948). LeVay (1995) insinuates that views on homosexuality are frequently changing and individuals are more likely to express their behaviours within their own cultures, as they will be accepted.

Pleasure

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As mentioned earlier, Kinsey and his colleagues conducted the first influential study on sexual behaviour. They found that children between the ages of 2 and 5 years touch their genitals. At such a young age children experience sexual pleasure, therefore it would be invalid to say this sexual behaviour is either learned or related to reproduction (Kinsey, 1948).

Abramson and Pinkerton (1995) point out that the even though fundamental purpose of sex is reproduction; sexual pleasure is biologically and physiologically grounded. The biological view of sexual pleasure is that penis erectile is apparent by the 38th week in the utero for a male fetus and for women; the clitoris is an organ whose unique purpose is to provide pleasure (Abraham & Pinkerton, 1995). The physiological feature to sexual pleasure is evident through an orgasm. It can be debated that the male orgasm has a reproductive purpose, however women achieve orgasm through clitoral stimulation and oral-genital sex than through vaginal penetration (Abraham & Pinkerton, 1995). These concepts indicate that reproductive behaviour is not the key purpose of individuals participating in sexual activities; we also engage in sexual behaviour because it is enjoyable.

Cognition and arousal

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Cognitions and arousal were found to be simultaneously significant in sexual arousal through the analysis of sexually functional and dysfunctional women (Palace and Gorzalka, 1992). The thoughts related to various stimuli impacts sexual motivation through influencing interpretations of behaviour. Different gender roles for men and women cause differences in interpretation of the same data (Wade & Tavris, 1966). For example, a survey of 400 teenagers found that behaviours felt conveyed romantic interest for women were the same actions boys considered invitations to sex (Zellman and Goodchild, 1983).

Researchers found that men and women experienced the same physiological arousal in studies comparing male and female physiological responses to male-produced erotic films (Laan, Everaerd, Van Bellen, & Hanewald; 1994). Men reported sexual arousal, while women reported a lack of arousal. However, when women viewed an erotic film produced by women, the female participants showed the same physiological arousal as they did to male-produced films, but reported greater sexual arousal. Researchers translate the difference was due to how women interpreted the content of the films (Johnson, 1997).

Attraction

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Physical Attraction: An Important Element

Attraction to others is another element of sexual motivation. It has both a nature and nurture perception; it is natural to seek out attractive partners, yet we are drawn towards companions who share similar qualities to us. Elements such as proximity, familiarity and similarity have been identified within the role of attraction (Kalat, 1996).

One form of human’s attraction to one another is the well-known technique “Playing Hard-To-Get” (Hatfield, Walster, Piliavin & Schmidt, 1988). Individuals construct judgements about possible others based on how quickly a person returns a show of interest. Persons easily attained are seen as less attractive than those that produced a challenge due to the characteristics the relationship-seeker attached to her (Johnson, 1997).

Physical attractiveness is an important element in attraction. Experiments using blind dates displayed results for both males and females, in which the attractiveness of the blind date resulted in whether subjects anticipated a second date (Walster, Aronson, Abrahams, & Rottman, 1966).

Learning

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One of the most influential areas in sexual motivation is learning. Through observational learning we repeat behaviours that are rewarded and withdraw behaviours that have negative consequences. Certain stimuli may increase sexual arousal; therefore conditioning is believed to influence sexual motivation both positively and negatively (Johnson, 1997). For instance, one might become sexually aroused by lingerie due to the learned association with sexual pre-encounters such as a romantic night with their partner. Negatively, conditioning accounts for sexually deviant behaviour (O'Donohue & Plaud, 1994). For example, a paedophile might have been unintentionally aroused in the presence of a child, therefore would seek the same combination of elements to achieve sexual pleasure. After examining several studies which used behavioural and aversion therapy to change sexual behaviours, it was noted that conditioning plays a much smaller roles than previously believed (O’Donohue & Plaud, 1994).

Sociocultural influences

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Fundamental changes in sexual behaviours have been seen since the sexual revolution in the 1960s and 1970s. This heavily impacted female sexuality than male sexuality. Cultural events, historical conditions, socialisation, peer pressures and influences severely affect female sexuality (Baumeister, 2004). The degree to which the sex drive can be shaped by social, cultural and situational factors is known as “erotic plasticity”. Low plasticity insinuates an inflexible sex drive, while high plasticity entails the capacity to change and adapt (Baumeister, 2004)

Women’s sexual motivation changes over time, in comparison to men’s sexual motivation, which remains relatively constant (Klusmann, 2006). High plasticity permits individuals to change their sexual patterns throughout their life. Women report variations in the amount of sex overtime, while men tend to keep their amount of sex constant (Kinsey et.al, 1953). Men’s preferences to be either heterosexual or homosexual remain the same overtime, however, women are more likely to switch back and forth (Baumeister, 2004). The National Health and Social Life Survey (NHSLS) showed a relationship between sexual practices through education and religion (Baumeister, 2004).

Attitudes and culture

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Sexual behaviours among cultures

Attitudes are defined as relatively stable evaluations of a person, object, situation or issue (Wood et.al, 1996). Culture is defined as a set of shared goals, values, attitudes and expectations that distinguish a group (Reeves, 2009). Behaviours normally considered proper in one culture, may be improper in another; hence attitudes towards sexual behaviours are culturally learned. For instance, some cultures find kissing repulsive, whereas others find kissing an appropriate form of sexual behaviour (Tiefer, 1995).

Different gender roles among society cause men and women to have different attitudes toward sexual behaviours. Weinberg, Lottes & Shaver (1995) compared Swedish and American college students to examine whether differences in attitudes were culturally drawn or innate gender differences. Sweden is known to have more relaxed sexual standards and women are seen to share equal power in society[factual?]. Results from the study showed male and female Swedish participants had similar attitudes towards sexual behaviours, whereas American participants, as expected, had different attitudes between males and females about what constituted suitable sexual behaviours (Weinberg et.al, 1995).

Gender differences in sexual drive

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Sex drive is measured through sexual arousal, sexual fantasy, and masturbation. It has been found across many studies that men think about sex more often and report more frequent arousal. This shows that males have a stronger sex drive in comparison to women (Baumeister, Catanese & Vohs, 2001).

MEN WOMEN
Have a stronger sex drive

Physical attractiveness & youth are important when considering a sex partner

Want sex with multiple partners
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Less interested in sex

Social security and material resources are important when considering a sex partner

Do not want sex with many partners

[factual?]

Pheromones

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Odours and smell play a significant role in human sexual interactions, sexual arousal and mating (Kohl & Francoeur, 1995). Pheromones are chemical messengers, which transport information between individuals of the same type. They are concealed fragrances, which cannot be smelt.

Pheromone odours are released through all areas of the body through skin cell secretions and gaseous glandular secretions. The theory of pheromones establishes the idea that the biological structures and physiological responses in humans are similar to those of other animals. The Vomeronasal Organ (VNO) is a structure in most mammals that is accountable for sensing pheromones via receptors, which transmit information to the brain, triggering hormonal changes. These changes are the basis for preparing an animal for sexual activity. McClintock (1971, as cited in Schank 2006) proposed that synchronising of the female menstrual cycle was caused by pheromones; hence the influences of pheromones on sexual behaviour in animals could be similar to our own (Kohl & Francoeur, 1995).

How can sexual motivation be pursued happily and safely?

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Safe Sex. No Regrets

The concept of self-efficacy is a practice researchers seek to understand individual’s motivations to pursue safer sex (Morton, Kim & Treise, 2011)[say what?][improve clarity]. Self-efficacy can be described as an individual’s believe in his/her ability to perform a particular behaviour in a given condition (Bandura, 1986).

The Protection Motivation Theory (PMT) predicts that motivation to adopt a suggested surviving response (e.g., regular use of condoms) will be dependent on an individual’s assessment of the severity of the threat (Morten et al, 2011). The study conducted by Morton et al., (2011) aimed to inform women to not only understand their risk of contracting STDs, but to also feel capable of raising and discussing these concerns openly with their partners.

The Extended Parallel Process Model (EPPM) suggests that as threat awareness increases, the level of self-efficacy controls the course of action taken to alleviate the threat (Morton et al, 2011). Response efficacy, or the degree to which a future reaction to a problem will be active, is influenced by self-efficacy.

Research limitations

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Sexual motivation has been a complicated topic for researchers for many years due to the private nature of the issue at interest. Most forms of collecting data for sexual research are through interviews or questionnaires (Johnson, 1997). Additionally, surveys, self-reports, clinical evaluations and volunteers in laboratory settings are other used research methods. Self-report and surveys have probability for error as individuals can make intentional errors (to provide socially-acceptable responses) or accidental errors (by forgetting) or unavoidable errors by not knowing the true nature that motivates their sexual behaviours (Walster, Aronson, Abrahams & Rottman, 1966). Kinsey and colleagues used face-to-face interviews during their research and critics discuss that this may have led interviewees to provide answers that are socially desirable (Kinsey et.al 1953).

Volunteers in sex studies are often from a selected group of participants, therefore it is difficult to generalise data. Volunteers who are willing to answer questions such as “how often do you get an orgasm?” are probably more sociable than the broader population. Masters and Johnson’s (1966) study using direct observation of participants in a laboratory setting is one of the most influential studies conducted with this method (Masters & Johnson, 1966). Finally, studies of human sexual behaviour involving the differences between genders or sexual orientation are descriptive; consequently it is difficult to uncover a correlation between the variables (Johnson, 1997).

Summary

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Sex is everywhere. Sex is growing in importance[factual?]. Sexual motivation is the drive that generates our sexual interest and behaviour. The chapter explored what motivates us sexually. In doing so, the role of evolution, the major factors in sexual motivation and gender differences have been discussed. Empirical evidence shows that males have a stronger sex drive than women, men want more sexual partners, want sex with multiple partners and have a strong sex rive throughout their lives. Pheromones were linked to human sexual motivation through the idea of synchronisation of the female menstrual cycle. The concept of self-efficacy determines how human sexual motivations can be pursued safely and happily with regards to two theories; the Protection Motivation Theory and The Extended Parallel Process Model. Finally, the research limitations in sexual motivation are due to the reserved nature of the topic. On the whole, the reader should now be equipped with a wide-ranging knowledge on what constitutes sexual motivations, and what behaviours should be accepted in order for the reader to pursue sexual behaviours safely and happily.

Interesting facts

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Did You Know?

Auto-erotic asphyxiation causes between 500 and 1000 deaths per year (Lamm, 2005)

Earlier this year a British court banned a 41-year old man from having sex as he had an IQ of 48 (Staff Writers, 2011)

Japanese women were the first to use Ben Wa Balls which are inserted into the vagina to enhance sensation during sex (www.benwaballs.net)

Islamic schools in Australia are banning sexual health classes (Milburn, 2006)

See also

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References

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Abramson, P. R. & Pinkerton, S. D. (1995). Pleasure: Thoughts on the Nature of Human Sexuality. New York, NY: Oxford University press.

Bandura, Albert. 1986. Social Foundations of Thought and Action: A Social Cognitive Theory. Englewood Cliffs, NJ: Prentice Hall.

Baumeister, R. F. (2004). Gender and erotic plasticity: Sociocultural influences on the sex drive. Sexual & Relationship Therapy, 19(2), 133-139. doi: 10.1080/14681990410001691343

Baumeister, R. F., Catanese, K. R., & Vohs, K. D. (2001). Is there a gender difference in strength of sex drive? Theoretical views, conceptual distinctions, and a review of relevant evidence. Personality & Social Psychology Review (Lawrence Erlbaum Associates), 5(3), 242-273. Retrieved from http://ezproxy.canberra.edu.au/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=4802747&site=ehost-live

Buss, D. M. (1995). Psychological sex differences: Origins through sexual selection. American Psychologist, 50(3), 164-168. doi:10.1037/0003-066X.50.3.164

Buss, D. M., & Schmitt, D. P. (1993). Sexual strategies theory: An evolutionary perspective on human mating. Psychological Review, 100(2), 204-232. doi:10.1037/0033-295X.100.2.204

Fisher, H. (1993). Biology: The natural history of monogamy, adultery, and divorce. Psychology Today, March/April: 40-45, 82.

Hatfield, E., Walster, G. W., Piliavin, J., & Schmidt, L. (1988). "Playing hard to get": Understanding an elusive phenomenon. Readings in Social Psychology: Classic and Contemporary Contributions. pp. 123-132.

Hokanson, J. E. (1969). The Physiological Bases of Motivation. NY: John Wiley & Sons, Inc.

Kalat, J. W. (1996). Introduction to Psychology, 4th ed. Pacific Grove: CA Brooks/Cole Publishing Company.

Kaplan, H. S. (1979). Disorders of Sexual desire: and other new concepts and techniques in sex therapy. New York, NY: Simon and Schuster.

Kinsey, A. C., Pomeroy, W. B., & Martin, C. E. (1948). Sexual behaviour in the Human Male. Philadelphia, PH: W. B. Saunders Company.

Kinsey, A. C., Pomeroy, W. B., Martin, C. E., & Gebhard, P. H. (1953). Sexual behaviour in the Human Female. Philadelphia, PH: W. B. Saunders Company.

Klusmann, D. (2006). Sperm competition and female procurement of male resources as explanations for a sex-specific time course in the sexual motivation of couples. Human Nature, 17(3), 283-300. Retrieved from http://ezproxy.canberra.edu.au/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=23002597&site=ehost-live

Kohl, J. V. & Francoeur, R. T. (1995). The Scent of Eros: Mysteries of Odour in Human Sexuality. New York: Continuum.

Laan, E., Everaerd, W., Van Bellen, G., & Hanewald, G. J. F. P. (1994). Women's sexual and emotional responses to male- and female-produced erotica. Archives of Sexual Behaviour, 23(2): 153-169.

Lamm, Steven, M.D. 2005. The Hardness Factor. New York, NY: HarperCollins Publishers.

Leger, D. W. (1992). Biological Foundations of Behaviour: An Integrative Approach. NY: Harper Collins Publishers Inc.

LeVay, S. (1995). Queer Science: The Use and Abuse of Research into Homosexuality. Cambridge, MA: The MIT Press.

Masters, W. H., & Johnson, V. E. (1966). Human Sexual Response. Boston, MA: Little, Brown and Company.

Meston, C. M., & Buss, D. M. (2007). Why humans have sex. Archives of Sexual Behaviour, 36(4), 477-507. doi:10.1007/s10508-007-9175-2

Milburn, C (2006, May). Muslim Sex Education: Just Say No. The Sydney Morning Herald

Morton, C. R., Kim, H. and Treise, D. (2011), Safe Sex After 50 and Mature Women's Beliefs of Sexual Health. Journal of Consumer Affairs, 45: 372–390. doi: 10.1111/j.1745-6606.2011.01209.x Johnson (1997) Human Sexual Motivation. Retrieved from the California State University Northbridge website: http://www.csun.edu/~vcpsy00h/students/sexmotiv.htm

No Sex For IQ Low Man (2011, February) Star Observer Newsletter. Retrieved from http://www.starobserver.com.au/news/2011/02/15/no-sex-for-low-iq-man/44618

O'Donohue, W., Plaud, J. J. (1994). The conditioning of human sexual arousal. Archives of Sexual Behaviour, 23(3):321-344.

Palace, E. M., Gorzalka, B. B. (1992). Differential patterns of arousal in sexually functional and dysfunctional women: Physiological and subjective components of sexual response. Archives of Sexual Behaviour, 21(2):135-159.

Reeve, J. (2009). Understanding motivation and emotion (5th ed.). Hoboken, NJ: Wiley

Schank, J. C. (2006). Do human menstrual-cycle pheromones exist? Human Nature, 17(4), 448-470. Retrieved from http://ezproxy.canberra.edu.au/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=26579744&site=ehost-live

Tiefer, L. (1995). Sex Is Not A Natural Act and Other Essays. Boulder, CO: Westview Press.

Trivers, R.L (1974) Parent-Offspring Conflict, American Society of Zoologists: Integrative & Comparative Biology, 14 (1), 249-264, doi: 10.1093/icb/14.1.249

Wade, C. & Tavris, C. (1996). Psychology, 4th ed. New York: Harper Collins College Publishers.

Walster, E., Aronson., V., Abrahams, D., & Rottman, L. (1966). Importance of physical attractiveness in dating behaviour. Journal of Personality and Social Psychology, 5:508-516.

Weinberg, M. S., Lottes, I. L., & Shaver, F. M. (1995). Swedish or American heterosexual college youth: Who is more permissive? Archives of Sexual Behaviour, 24(4):409-437.

Wood, S. E., & Wood, E. G. (1996). The World of Psychology, 2nd ed. MA: Allyn and Bacon.

Zellman, G. & Goodchilds, J. (1983). Becoming sexual in adolescence. In: E. R. Allgeier & N. B. McCormick, eds., Changing Boundaries: Gender Roles and Sexual Behaviors. Palo Alto, CA: Mayfield.

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