Chapter 1 – Sexuality in perspective

Sexual behaviour is a diverse phenomenon and occurs in several physical situations, social contexts and is experienced differently by everyone. Everyone has a complex set of motivations and external influences that determine the decision to engage in sexual behaviour. It is difficult to answer all the questions about sexuality within one discipline. The study of sexuality is important for the following reasons:

1. The exchange of sexual information is a taboo in many societies.
2. For many people, sexuality is an important motivation in life.
3. Some people experience difficulties and problems with their sexual functioning.

What is the difference between sex and gender?

The definition of gender is whether someone is male, female or other, such as trans. However, sometimes the word sex is used to describe gender, for example on a job application form. Most of the times sex refers to sexual behaviour, or reproduction. The ambiguity in the use of the word sex causes confusion. In the context of this book, the term sex describes sexual activity and gender refers to being male, female or other. Besides the ambiguity in the use of the word sex, there are other problems with the difference between sex and gender. A lot of contemporary research is based on the gender binary, this is the notion that there are only two genders, being male and female. Also, the activities that are included in sex are debatable. Biologists describe sex as every behaviour that can cause the encounter of an egg-cell and sperm-cell. However, sexual behaviour is not only used for reproduction, but also for recreation. Therefore, in this book, sexual behaviour is described as behaviour that cause arousal and increases the chance of an orgasm.

What is the history of sexuality about religion and science?

Until about one hundred years ago the sexual available knowledge came from religious sources. The ancient Greek already told myths about the existence of hetero -and homosexuality. This way they could understand these sexual orientations. In Christianity they believed that having a “wet dream” was caused by having sex with the mythical creatures’ incubi ­and succubi. The person having the wet dream was sometimes accused of witchcraft. Muslims believed that sex was one of the most pleasurable things in life, this reflects upon the teachings of the prophet Mohammed.   

Scientific research on sexuality started in the nineteenth century, even though at that time it was still illegal according to religion. In his book “theoretical perspectives on sexuality” Freud describes the cultural background of sexual behaviour for the first time. Norms concerning sex used to be very strict and rigid causing sexual tension and conflict. The psychiatrist Richard von Krafft-Ebing (1840-1902) described the pathology of sexual behaviour for the first time. Hirschfeld was interested in research about homosexuality and introduced the term transvestite. Only in the twentieth century, there was a breakthrough in scientific research about sexuality. This was the period in which large-scale surveys were conducted in the United States. Because of this research, sexual disorders and alternating sexual orientations were exposed for the first time. At the same time, scientists started investigating the biological processes of sexual behaviour.  

What is the influence of mass-media on sexuality?

The mass media had a significant influence on knowledge on sexuality comparable to religion. Especially television was of great importance, in only one hour of American television, adolescents were exposed to a mean of seventeen behaviours or conversations about sex. Only two percent of these images show sexual repercussions. Many of the American insights about sexuality therefore come from mass media, instead of scientific research. The concept of cultivation is the exposure to sexual behaviour in mass media where people believe this resembles reality. The second major impact of mass media is called agenda setting. It is defined as the choices that news-creators make in what information they present to their audience. The third influence of mass media is social learning. In social learning, the characters in films serve as social models that people use to construct their ideas about the reality of sex. Besides television, the internet is an important source of sexual knowledge. There are both positive and negative norms displayed on the internet. Besides bad information about sexual behaviour, positive information about sexual health is widely available and promoted. This caused the number of sexual abuses over the internet to decrease over the last years.

What are cross-cultural perspectives on sexuality?

Culture is defined as the traditional norms and values that are transferred through group members by cultural symbols, such as language. These ideas and values are the basis for behavioural patterns for members of that group. Etnocetrism influences that understanding of sexual behaviour because most people experience sex through the eyes of their culture. The pattern in which people experience sex is therefore seen as correct. However, different cultures have very different attitudes about sex. There has not been a society so far that has been able to guarantee complete freedom of sexual behaviour. There are always rules concerning sex. For example, almost every society has incest taboos in which it is illegal to have sex with a blood relative. Also, in most societies rape or sexual assault is forbidden. Besides rules about incest and rape, many differences exist between sexual norms:

1. Variations in sexual techniques resemble the differences in techniques of sex. Kissing of a partner is a very normal thing to do in our society but is seen as disgusting by the Thonga Africans. Also,cunnilingus, the stimulation of the female genitals is seen as completely normal in Western societies. In different cultures this is practiced in a distinctive way. The amount of sex deviates in each culture. The Irish natives have the least sex between couples, maybe only once a month while the Mangaians have sex several times a night. Almost every culture describes norms on postpartum sex, which is the prohibition of sex after pregnancy.
2. Masturbation or self-stimulation is tolerated in some cultures while forbidden in others. Especially rules about female masturbation vary between cultures.
3. About Pre -and post marital sex there are distinct opinions between cultures. In the Pacific, pre-marital sex is completely normal and approved in ninety percent of the occasions. However, seventy-three percent of cases of premarital sex is disapproved in the Mediterranean area.
4. Homosexuality is often disapproved of in the United States. In other cultures, homosexuality among men is promoted. It seems there are two important universal rules about homosexuality. The first is that homosexuality exists in every culture. The second is that sex between two people of the same gender is never the primary form of intercourse.
5. Attractiveness determines the choice for a sexual partner. The norms of attractiveness vary among cultures but there seems to be one conformity, a pale skin colour is seen as unattractive in most cultures.

What is the influence of differences in social class and ethnicity on sexual behaviour in the United States?

Some varieties in the United States can be explained in terms of differences in social class, others can be explained in terms of ethnicity. Social class is often determined by education. The influence on sexual behaviour is that women that enjoyed a higher education are more likely to use birth control. People with a lower education are therefore more likely to have children at a younger age. These children often have a lower education. This means that sexuality might also influence social class. Besides the influence of social class, there are ethnical differences in sexuality.

• In the Afro-Caribbean culture, women should be modest. They see the African Americans as being sexually undisciplined. The percentage of African Americans that engage in marriage is lower than other ethnic groups. This is caused by the obstacles they face in finding decent employment to take care of a family.
• Latinos are people from Latin American heritage. They have a different view on sexuality compared to most Americans. Gender-roles are highly specific and are taught during childhood. The gender-roles in the Latino culture are characterized by machismo or macho. It literally means masculinity and implicates that a man is responsible for the honour and well-being of his family. The female form ismarianismo and mean that motherhood is highly valued. Also, virginity until marriage is an important consideration for a woman. Familismo means that family is important, and support, loyalty, solidarity and family-honour are central values in the Latino culture.
• Asian Americans represent different cultural groups. They include Chinese, Japanese but also Indians. Especially the Chinese have a repressive outlook on sex. The people from Cambodia believed that withholding information about sex would lead to a decrease in premarital sex. Their conservative cultural values, relevant for sexual attitudes are the following:
  1. Collectivism where people value others more than themselves. Openness of sexual behaviour could lead to discomfort in others and is thus not tolerated.
  2. Conformity to norms means that people need to live up to high expectations of their family and society. Shame and losing of face are important conditions on how to behave.
  3. Emotional control means that emotions should not be publicly displayed. Love and passion should not be showed to the outside world. 
• American Indians are the native Americans and exist from different tribes. Men of this culture are masculine and often pictured naked. Females from the native American culture are vulnerable, attractive and maidenly. They have strict rules about pre-marital sex.

Racial microaggressions are subtle insults that are displayed to people of another (racial) background. It happens unnoticed but can lead to stress in the victim. There are gender microaggressions, sexual orientation microaggressions and microaggressions against transgenders.

What is the significance of cross-cultural research on sexuality?

Scientific research on human sexuality is important for two reasons:

1. It helps to determine the variation in sexual behaviour and help to put this into perspective.
2. These studies provide important insights in the importance of cultural learning on sexual behaviour. Cultural differences show that sexual behaviour is not only caused by biological factors.

What are cross-species perspectives on sexuality?

People are just one of the different species. Every specie is involved in sexual bahaviour. We can learn about human sexual behaviour by studying sexual behaviour in animals.

1. Masturbation is present in many animal species. Especially apes often masturbate. Not only male, but also female masturbation is observed in animal species.
2. Homosexuality is present in other animals and suggests we are naturally bisexual. This is because homosexual behaviour is present in all animal species.
3. Sexual signalling or flirting happens across all species. It is an universal act.
4. Uniqueness of humans. In higher animal classifications, such as primates, sexual behaviour is guided more by hormones than internal impulses. The environmental influence on sexual behaviour is more present in primates than in fish for example. For humans the environment is a key influence on sexual behaviour. There is not much of human sexual behaviour that is unique, and for humans only, except for the cultural influences.  
5. Non-sexual use of sexual behaviour is often described as using seks to express dominance. It happens in primates, but also in humans. For instance, rape is a desire for dominance that is expressed using sexual behaviour.

What is the sexual health perspective?

Sexual health is the political and social movement that is directed towards a shift of focus towards sexual health and sexual rights. Discussions about sexual health are about pathology, such as the infection with the HIV-virus. However, the concept is a lot bigger and includes sexual rights. These are universal basic rights that people have regarding their sexuality. This includes self-determination, freedom of sexual abuse and the right to express oneself sexually.

Summary: chapter 1 – Sexuality in perspective

• A lot of contemporary research is based on the gender binary, this is the notion that there are only two genders, being male and female. Also, the activities that are included in sex are debatable. Biologists describe sex as every behaviour that can cause the encounter of an egg-cell and sperm-cell. However, sexual behaviour is not only used for reproduction, but also for recreation. Therefore, in this book, sexual behaviour is described as behaviour that cause arousal and increases the chance of an orgasm.
• Culture is defined as the traditional norms and values that are transferred through group members by cultural symbols, such as language. These ideas and values are the basis for behavioural patterns for members of that group. Etnocetrism influences that understanding of sexual behaviour because most people experience sex through the eyes of their culture.
• Sexual health is the political and social movement that is directed towards a shift of focus towards sexual health and sexual rights.

Study note: chapter 1 – Sexuality in perspective

• Make sure that you can explain the sexual differences within the United States. What type of cultural groups exist and what influence does their culture have on their sexual behaviour?
• You should know what influence the mass media had on the development of knowledge about sexuality. One example would be what is meant with agenda setting and what is it’s influence on knowledge about sex?
• What is the difference between sex and gender?

Chapter 2 – Theoretical perspectives on sexuality

According to Freud, nothing is more important than the choice for a reproductive mate. He views sex in terms of libido, which can be expressed with sexual behaviour. On the other hand, Bandura would argue that sexual arousal leading to an orgasm is a positive reinforcement that will lead to the couple repeating this act more often.  

What are the evolutionary perspectives on sexuality?

The evolutionary biology to understand social behaviour in animals is called socio-biology. The socio-biologist will study human sexual behaviour by examining patterns in other species. From the evolution perspective the most important function of sex is producing healthy offspring. This happens through sexual selection, in which animals that are best at adapting to their environment will survive. Humans choose their mates based on physical attractiveness, which according to the socio-biologist is a way of evaluating one’s health and vigour. This could indicate a better offspring. However, if people only chose mates based on maximum reproductive success, attractiveness should be a more important indicator of mate selection in unhealthy countries.

There are several hindrances that can occur with reproduction, two of them are infant vulnerability and maternal death. The first is reduced when the mother is providing care continuously, including breastfeeding. Also, a pair-bond between mother and father and attachment between the child and its parents limit infant vulnerability. Parental investment means that parents are more interested in the survival of their own offspring and will invest significant resources to achieve this. Darwin proposed that sexual selection creates differences between females and males. There are two processes involved:

1. The competition of representatives from one gender (often males) for access to mating members of another gender.
2. Preferential choice by representatives from one gender (often females) for certain members of another gender.

This means that species compete among themselves in the mating process. The socio-biologic perspective has been criticized. Researchers argue that the biological determinism is an old-fashioned version of evolution and sex is no longer only reproductive.

What is the evolutionary psychology perspective on sexuality?

Evolutionary psychology focusses on psychological mechanisms, altered by natural selection. Behaviours that evolved as a result of sexual selection can be considered cognitive or emotional. People can have different strategies in choosing a partner for reproduction. A short-term strategy is when one chooses a partner based on immediate resources, such as food or money. A long-term strategy could be to choose someone who appears to provide resources for an indefinite future. Therefore, women with a long-term strategy should respond negatively to women who make sex easily available. On the other hand, females that pursue short-term strategies dress more provocatively. Researchers found that women pursue both long-term and short-term strategies. Another criticism is that in this view, every mating choice should have some kind of evolutionary purpose. The research also suggests that these strategies are universal, but the population studied are mostly Western Educated Industrialized Rich Democratic societies (WEIRD). It is not certain that these conditions hold when studies in other cultural societies.

What are psychological theories on sexuality?

There are several psychological theories that are relevant for studying sexual behaviour. These are the psycho-analytic theory, social exchange theory, learning theory and cognitive theory.

The psychoanalytic theory

The psychoanalytic theory is one of the most influential theories in psychology. Freud argues that sex drive, or libido is the primary force in sexual behaviour. The libido is focused on erogenous zones on the body. These zones are sensitive to stimulation and provide feelings of pleasure. The second influence is thanatos, the death instinct. According to Freud, personality exists of three parts: the id, ego andsuperego. The id operates based upon the pleasure principle and includes the libido. The ego uses the reality principle to keep track of the irrational id. The superego is referred to as consciousness. It operates based upon the idealism principle. It exists from moral goals instead of realistic goals. The id, ego and superego develop in sequence where the id is present at birth, followed by the ego and lastly the superego. According to Freud’s principles, there are several stages of development.

1. The oral stage in which pleasure is evoked from sucking and stimulating the lips.
2. The anal stage in which interest is mostly focussed towards elimination.
3. The phallic stage where a child’s (male) attention is focused towards the penis (phallus). In this stage the oedipus complex is present, where the boy sexually desires his mother. The boy then feelscastration anxiety which leads him to stop desiring his mother and identify with his father instead. The oedipus complex is considered a primary factor in human development. The third stage in a girl is different and is characterized by penis envy. She develops the electra complex where she desires her father. The resolution of the electra complex is dissimilar to the boy’s solution for the Oedipus complex. Therefore, Freud argues that girls remain immature compared to men.
4. After the phallic stage, the latency stage follows. It lasts until adolescence; sexual impulses are repressed and sexually there is not much happening.
5. The genital stage starts during puberty and sexual urges become more genital, oral and anal to promote their biological function of reproduction. It is possible that people remain fixed on one stage. For example, Freud argues that people that remain fixated on the oral stage have habits such as biting their fingernails.

There are some criticisms on the psychoanalytical theory. One of the major critiques is that scientific research is impossible. This is because most urges are unconscious and can not be studies using the currently available techniques. However, fMRI research has given some insight into Freud’s theories. Neuropsychoanalysis suggests bizarre imagery (from the id) is controlled by the prefrontal cortex. One of Freud’s main concepts is repression where people forget certain information as a defensive act. Even though this has been widely criticised, the social factors causing neural inhibition and impulse control could account for Freud’s idea of repression.  Other criticisms are Freud’s study subjects consisting of mentally ill individuals meaning his theory is more likely to resemble disturbances in the human personality rather than healthy behaviour. Also, females tend to disagree with Freud because of his male-centered perspective. They argue that boys have womb envy (Horney, 1926/1973) and there is no distinction is made between a vaginal orgasm and a clitoral orgasm. Finally researchers argue that Freud overestimated the biological factors in sex.

Learning theory

It is apparent that much of sexual behaviour is learned. It is not only driven by biological forces. Research about (sexual) behaviour in different cultural environments resulted in various principles of modern learning theory.

• Classical conditioning is associated with Pavlov (1849-1936). It exists from an unconditioned stimulus, followed by an unconditioned response. The process of learning that elicits the response without the stimulus is called classical conditioning. It has proved to be useful in explaining several phenomena in sexuality. One example is the explanation of a fetish, where someone has sexual desire for an object rather than a person.
• Operant conditioning is associated with Skinner and refers to the reinforcement (positive versus punishment) after receiving a stimulus. If the behaviour is followed by a reward, the behaviour is likely to occur again. Punishment of sexual behaviour, such as pain during intercourse can lead to diminishing of the desire to have sex. However, other types of punishment can result in continuing the behaviour privately. One example is getting caught while masturbating.
• Behaviour modification exists from techniques derived from theories on conditioning to change behaviour. These methods also apply to solving problems with sexual behaviour. One technique is aolfactory adversion therapy. Problematic behaviour is then punished using an aversive stimulus.
• Social learning is a complex learning theory involving the process of imitation and identification. They are useful in the explanation of gender identity. Once gender-specific behaviour is learned, the likelihood of occurrence is determined by its consequences. Creation of a sense of competence, or self-efficacy is achieved by promoting successful behaviour, such as anticonception.

Social exchange theory

The social exchange theory is based on reinforcement principles. It describes changes in relationships between people. Every behaviour comes with a certain cost or reward. According to the theory, humans behave hedonic and strive for optimal profits with our actions. Social relationships are characterized by the exchange of services and goods. The outcome of such a relationship is defined by its comparison level for alternatives. It also predicts when people change their relationships. The key concept is equity where people in a relationship believe the rewards weigh up to the costs. The matching hypothesispredicts that people choose mates based upon social characteristics and rewards on the dimensions of attractiveness, wealth and social status. The theory has been criticized because the applied ideas of rewards and costs do not always seem to apply in romantic relationships. Another criticism is that other motivations are downplayed by social exchange. The theory is unable to explain altruistic behaviour.

Cognitive theory

Cognitive psychologists believe that people’s thoughts and the way they think -and behave should be studied.

• Cognition can explain certain parts of sexuality. The basic notion is that thoughts shape what we feel. The cognitive approach states that psychological distress is caused by unpleasant thoughts. The labelling, evaluation and perception of events is crucial to our (sexual) experiences.

• The gender schema theory explains gender-role-development in terms of internal schemas. A schema is a framework that consists of general knowledge that someone has about a subject. The schema is used to organize one’s thoughts, feelings and emotions. It both helps -and distort our memories, especially when information is inconsistent with our schema. A gender-schema is a cognitive structure of behaviours, personality and appearance that is associated with either male or female. The gender schemas guide everyday behaviour and gender-stereotypes are very difficult to change.

What are critical theories about sexuality?

The theories that have been discussed so far are used to understand the nature of behaviour. The behaviours described in these theories are derived from groups, subcultures, associations and constructions of categories. The critical theories give a more in-depth description about the formation of these categories influenced by groups and subcultures.

Feminist theory

Feminist theory was proposed by many independent scholars and exists of four important assertions.

1. Gender as status and inequality: gender is a status characteristic where men often have greater status than women. It has allowed men to undermine the sexual expression of women.
2. Sexuality includes different topics, such as abortion, rape, birth-control, sexual harassment and pornography. According to feminists, women’s sexuality is repressed instead of expressed.
3. Gender roles and socialization: gender-roles display inequality and place restrictions on both women and men’s behaviour.
4. Intersectionality states that people should consider other’s group memberships, including gender, social class, sexual orientation and race.

Queer theory

Lately queer regained a positive attitude from homosexuals. The theory is broader than just homosexuals, it is about intersex and transgender too. The theory states that social categorization of sexual orientation should not fall into binaries (just two categories). It questions the gender binary that separates males and females. It also argues that sexual identities are not restricted for the individual. Another definition is that it challenges heteronormativity which is the belief that heterosexuality is the only normal and natural pattern of sexuality.

What are sociological perspectives on sexuality?

Sociologists study the influence of society on the expression of sexuality.

• Symbolic interaction theory states that human nature and social order is derived from symbolic communication between individuals. Behaviour is based on interaction with others. The meaning of an object does not depend on its qualities, but also on what a person might do with it. The views on people are thus goal-oriented and proactive. Especially for sexuality, it alerts us to engage in mutual effort in order to define a situation, by conscious thought, whereas sexual behaviour is often dependent on emotional decision making.
• Sexual scripts are learned by the outcome of social influence. The idea behind it is that human behaviour is somehow scripted. Sexual behaviour in this sense comes from prior learning and teachings of sexual etiquette. Scripts are the plans that people carry around in their head that determine behavioural patterns. Besides that, it also conveys the meaning of how we should perceive certain events or what guidelines to follow.
• Sexual fields are contextual factors determining sexual behaviour. The difference between the kind of intimacy that people will perform reflects the nature of the sexual field in each situation. A sexual fieldis defined as a site that is populated with people with erotic dispositions they project on each other and the space around them.

Social institutions

Most sociologists view sexuality using three basic assumptions, the first is that every society regulates the sexuality of its citizens. The second is that the inappropriateness or appropriateness of sexuality depends upon the institutional context in which it happens. The third assumption is that basic institutions of society affect the rules that citizens are subjected to by the government. Each of the institutions explained below has its own view on sexuality and an ideology about beliefs and behaviours.

• Religion is powerful in shaping sexual norms. The traditions of asceticism (abstinence of sexual pleasure) practiced by monks and priests is seen as virtuous. Sexual legitimacy is only reachable with heterosexual marriage with the goal of having children. This is called a procreational ideology.
• The economy influences sexuality by permitting a kind of togetherness where before the industrial revolution sexuality was closely monitored by family members. After the industrial revolution people started to spend more time outside of the house, thus the surveillance became less. This increased rate of affairs and same-gender sex. It is still prevalent today, where unemployment has a big influence on sexuality.
• The family influences sexuality because of the interpersonal relationships. There exists a triple linkage between love, marriage and sex. The relational ideology means that the link between love and sex can exist without marriage. The family also influences sexuality through the socialization of children and teach them appropriate behaviours.
• Medicine has become a major influence over the past years. The predominance of medicine on sexuality in the biomedical model is called medicalization of sexuality. It has two components: the first is sexual behaviours and conditions that are caused by health habits. The second are problematic experiences where medical treatment is helpful.
• The law institution influences sex by restraining people’s sexual behaviours. Laws determine (sexual) norms and therefore people will have very different views on sexuality across different societies.

Summary: chapter 2 - Theoretical perspectives on sexuality

• The evolutionary biology to understand social behaviour in animals is called socio-biology. The socio-biologist will study human sexual behaviour by examining patterns in other species. From theevolution perspective the most important function of sex is producing healthy offspring. This happens through sexual selection, in which animals that are best at adapting to their environment will survive.
• There are several psychological theories that are relevant for studying sexual behaviour. These are the psycho-analytic theory, social exchange theory, learning theory and cognitive theory.
• Most sociologists view sexuality using three basic assumptions, the first is that every society regulates the sexuality of its citizens. The second is that the inappropriateness or appropriateness of sexuality depends upon the institutional context in which it happens. The third assumption is that basic institutions of society affect the rules that citizens are subjected to by the government. Each of the institutions explained below has its own view on sexuality and an ideology about beliefs and behaviours.

Study note: chapter 2 - Theoretical perspectives on sexuality

• You should be able to explain the evolutionary, psychological, sociological and critical theories about human behaviour and how they explain differences in sexuality.
• How can knowledge about learning theory contribute to psychological treatment of sexual problems?
• In the book several viewpoints on how to explain sexual behaviour. In the schema theory they talk about schemas on sexual behaviour and how stereotypes are difficult to change. The queer theory is a response to this schema theory. The scripting theory seems to be the social alternative to the cognitive schema theory. How are sexual scripts related to the queer movement?

Chapter 3 – Sex research

Over the last few years there have been major improvements in sex research. The methods can differ on the following:

1. The measurement of sexuality: this can be self-report, biological measures or observation.
2. The number of subjects studied, either large or small groups.
3. Whether studies take place in the field or in a laboratory.
4. Sex can be manipulated or studied in natural occurrence.

It is important to study and understand these techniques and their limitations. It gives a better understanding in current sex research, but also in the research that is yet to come.

How can we measure sexual behaviour?

The first thing that needs to be decided is how to measure sexuality. There are several methods available:

• Self-reports are the most common way and exist of questions about people’s sexuality. They can be conducted on paper, with interviews or online.
• Behavioural measures include direct observation where participants are observed, and the behaviour is described. Another behavioural measure is eye-tracking where participants’ eye movements are studied when they look at images on a computer. Illegal sexual behaviour is studies using police reports. In the FBI they use uniform crime reports to study illegal sexuality. However, it only detects cases that are reported to the police.
• Implicit measures include the implicit associations test in which the strength of associations to sexual content is measured. People tend to respond faster when an association is stronger. People are asked to divide sexual images or text into categories, such as pleasant and unpleasant.
• Biological measures are measures of response to sex. There are genital measures in which arousal is measured by vaginal changes in women and erection changes in men. MRI and fMRI are now increasingly being used, they look at autonomy and brain regions involved in sexual behaviour. Strengths are its normativity, but limitations are the complicated statistical research needed to read the results and there is a lot of noise if the participant does not lie completely still in the scanner. Also, the results depend on the choice of sets of stimuli.

What are issues in sex research?

One important consideration is the population that is being used. The question here is who do we want to study? A scientist should always take a sample of the population. If the sample is a random sample,the results can be generalized to the population that was originally identified. However, random sampling is difficult because selecting a random one out of every fifty people in the United States can be tricky. Therefore, probability sampling is often used. Here, participants are selected based on characteristics meaning that the results are not generalizable to the whole population. Sampling exists from three stages:

1. Identification of the population.
2. Choosing a method for sampling.
3. Contacting the people in the sample. Here, researchers encounter the problem of refusal or nonresponse. The researcher needs to use volunteers, which causes the sample to contain volunteer bias,people that participate might be different from the ones that refused to participate. Moreover, women are less likely to volunteer for sex research than men.

Because there are some issues with sampling, convenience sampling can be used. It includes volunteers that came to sex’ therapist offices and volunteer to participate. It is chosen in a haphazard manner and relative to the population of interest. It differs from a probability or random sample.

Another issue is the accuracy of measurement. Participants in sex research often engage in purposeful distortion, when giving self-reports, they distort reality. They might exaggerate sexual behaviour (enlargement) or conceal certain things (concealment). To avoid distortion the participants are told that for scientific purposes, the information they give must be as accurate as possible, besides that anonymity must be guaranteed. However, even with these measures, there are two factors that impact the accuracy of responses:

• Memory recall is needed to retrieve information on sexual behaviours years ago. One solution is asking about current sexual behaviour. However, children cannot be asked due to ethical and practical problems. One alternative is to use daily diaries in which people report their behaviour.
• Difficulties with estimates arise when people are asked about frequencies. People cannot estimate very accurately which leads to inaccuracy in the self-report data.
• Evidence of the reliability of self-reports can be measured. One measure is test-retest reliability where the respondent is asked to answer a series of questions once, and again when some time has passed. The correlation between the answers is noted as test-retest reliability. Another option is using a computer-assisted self-interview (CASI) method. The questions can be read aloud in addition to written questions for people that are poorly in reading questions, while giving the same level of privacy.
• Accuracy of behavioural observations is an issue with natural observation of sexual behaviour. Direct observations have an advantage on self-report measures in accuracy but have their own problems. For example, they are expensive, time consuming and only a small sample can be studied. The sample that can be used probably consists of an unusual population that allows researchers into their bedroom.
• Extraneous factors can influence sex research, these factors include race, gender or age of the respondents and the researchers.
• Ethical issues arise when participants feel their privacy is being violated. A solution can be the use of an informed consent, where participants have the right to be told the purpose of the research. Another solution is the protection from harm where the levels of stress and discomfort are minimized. The principle of anonymity is an example of protecting participants from harm. The justice principle means that risks and benefits of participating should be equally distributed across research groups. A cost-benefit approach means that the stress of participants should be minimized and that what is left is the cost. Researchers should consider if the benefits outweigh the costs.

What are examples of major sex surveys?

When data is collected from a large sample of people by using questionnaires this is called a major sex survey.

The Kinsey reports

The first major sex survey was done by Alfred C. Kinsey between the late 1930s and 1940s. Even though the results are of historical interest, the research is a good example. The sample of the research was obtained by interviewing 5,300 males. Their responses were reported in a scale, called the sexual behaviour in the human male (1948). Females contributed to the sexual behaviour in the human female(1953). They chose not to use probability sampling because of non-response problems. However, there is currently no information about the accuracy of the used sample. College students, well-educated people, young people, protestants, people from Indiana and people from the Northeast were over presented. He used face-to-face interviewing by Kinsey himself or his well-trained colleagues. They cross-checked the participant’s reports for false information. The sample contained a unlikely high level of homosexuals and people with unusual sexual practices. Therefore, it is impossible to say how accurate the Kinsey statistics are.

The NHSLS

The National Health and Social Life Survey (NHSLS) used slipshod sampling. A large sample of the national population was needed to say what sexual behaviour looked like in America. The researchers used probability sampling for this purpose. It excluded only three percent of the population, which were institutionalized people. Data was obtained with interviews in addition to a written questionnaire. The NHSLS is one of the best surveys because outstanding sampling -and interview techniques were used.

The NSSHB

The National Survey of Sexual Health and Behaviour (NSSHB) is the most recent major survey done in the United States. A probability sample was used, and 5,865 people participated. The method they used for sampling, which was based on the random selection of phone numbers was excellent. However, it caused the response rate to be low. Therefore, it is not possible to be sure the result can be generalized to the whole population. They obtained a good sample size and ethnic diversity though.

Sexual behaviour in Britain and Australia

Every ten years, a major sex survey is conducted in Britain called the National Survey of Sexual Attitudes and Lifestyle (Natsal). They use postal codes for sampling, which is an excellent method and the sample size is good (about 15,162 completed interviews). Interviewers went to participants homes to complete the survey. Also, urine samples were collected to test for sexual transmitted diseases. Another major research was done in Australia where computer-assisted telephone interviews were used to study health and relationships. Their findings were that the age of first intercourse has decreased over the last couple of years which is consistent with findings in the United States.

A survey of Latino women

Latinas in the United States were interviewed to assess patterns of interpersonal victimization. This included sexual assault and violence by one’s partner. The study was called SALAS, meaning Sexual Assault among Latinas. Interviews were conducted over the phone in either English or Spanish. It used many methods suitable for investigating among minority populations. Sex research in minorities indicates sensitive issues and need additional consideration in language and ethnicity of the interviewer.

Magazine surveys

Magazine surveys are using samples that our out of their control. They are distributed among different clienteles and only to readers of the magazine. The response rate is about three percent, which is not even generalizable to the population of people reading the magazine. Ethnic backgrounds, marital status and age are unknown. These details are crucial in evaluation of the outcomes. Therefore, it would not be legitimate to infer conclusions based upon these statistics.

What are studies of special populations?

An example of a study of a special population is the Coxon Study of gay men in the AIDS era. The project was called SIGMA and was used to understand the behaviour of men in the AIDS era. Participants were divided into two groups, one was the “out” and easy to administer gay people that were recruited in bars and pubs. The second, more difficult group consisted of “hidden” gays. After that respondents were asked to nominate persons in the other category. This technique of sampling is called snowball sampling or respondent-driven sampling. The study used the daily diary method where participants reported their sexual experiences. It resulted in a richer and contextualized overview of people’s sexual experiences. However, memory in self-reports is a major concern.

What are the advantages and disadvantages of web-based surveys?

A whole new era in sex research began by administering web-based surveys. Advantages were that larger and broader samples could be recruited. They also have an advantage in studying specific populations defined by their sexual behaviour. Especially when studying taboo behaviour. They also have the advantage to eliminate extraneous factors, such as the ethnicity of the interviewer. A disadvantage is that the researcher does not have any control over the environment. Also, individuals might respond multiple times or sabotage the interview with fake answers.

What is media content analysis?

The influence of mass media on sexuality can be analysed by content analysis, it consists of a set of procedures that are utilized to make valid inferences about text. It can be any text, an article in a magazine, a rap song or a romance novel. Again, sampling becomes an issue. The population must be defined an whether you want to analyse over a specific time period. Then, a coding protocol should be established. One important consideration is intercoder reliability, the correlation or percentage of agreement between different coders rating the same texts. It is a powerful scientific technique that allows people to know how the media is portraying sexuality.

What are qualitative methods?

Most research discussed so far uses quantitative measures, however qualitative measures can give useful insights into the subject as well. Qualitative research is done in a naturalistic, holistic manner which includes observation and in-depth interviewing of a participant. The results are conveyed into words instead of numbers. It seeks a complete picture of the participant and the context. Ethnography is a qualitative method that is used to provide a description of a social setting, society or human group. Participant-observer techniques include methods where the researcher becomes part of a community in order to observe its behaviour.

What are experimental methods?

The research discussed so far looks at natural occurrence of sexual behaviour. Such research is called correlational, meaning that the researcher does not manipulate variables, but studies the natural occurrence of relationships between variables. An experiment is another type of research where the experimenter studies an independent variable which is manipulated and its dependent variables that occur as a result of the manipulation of the independent variable. All other factors are held constant. The researchers is then permitted to make causal inferences about the behaviour observed in his participants.

What is meta-analysis?

Meta-analysis is a technique to create order among different studies on the same topic. It is a statistical technique where results from different studies are combined to determine what, taken together these studies say. There are three steps that need to be taken:

1. The researcher must locate all the previous studies based on the question that needs to be investigated.
2. For each study, the researcher must compute a statistic to measure the direction and difference between males and females. This is the value of d.
3. The researcher must average all the values of d over all the studies.

What statistical concepts are being used?

There are several important statistical concepts to understand before understanding reports of sex research.

• Average is used to summarize data. The mean is the average of scores of the respondents. The median is the middle score.
• Variability is an indication of the average of all the respondents. This can be used to judge the numbers in a single respondent or group of respondents.
• Average versus normal is an important consideration, conclusions based on a single average number are often mistaken. It is important to note that variability in (sexual) behaviour should be considered in classifying normal behaviour.
• Incidence versus frequency is another important consideration. Incidence refers to the percentage who engaged in a specific behaviour. Frequency is how often they do this. Cumulative frequency is the percentage of people who engaged in specific behaviour before a certain age.
• Correlation is the number that can be used to measure a relationship between two variables.

Summary: chapter 3 – Sex research

• One important consideration is the population that is being used. The question here is who do we want to study? A scientist should always take a sample of the population. If the sample is a random sample, the results can be generalized to the population that was originally identified. However, random sampling is difficult because selecting a random one out of every fifty people in the United States can be tricky. Therefore, probability sampling is often used. Here, participants are selected based on characteristics meaning that the results are not generalizable to the whole population.
• Meta-analysis is a technique to create order among different studies on the same topic. It is a statistical technique where results from different studies are combined to determine what, taken together these studies say.
• Most research discussed so far uses quantitative measures, however qualitative measures can give useful insights into the subject as well. Qualitative research is done in a naturalistic, holistic manner which includes observation and in-depth interviewing of a participant. The results are conveyed into words instead of numbers.

Study note: chapter 3 – Sex research

• In this chapter several difficulties in sex research have been described. The most difficult being sampling. What is sampling exactly and what kind of problems arise when sampling for sex research? Also, be sure to know what impact this can have on the interpretation of your results.
• Make sure to know the difficulties that can arise in using self-report measures in research on sexual behaviour. For example, can we trust people’s memory to be completely accurate?
• Understand the most important concepts in sex research, described in the final paragraph.

Chapter 4 – Sexual Anatomy

The purpose of this chapter is to provide information about the functionality of parts of the reproductive organs.

What are the female sexual organs?

The female sexual organs are divided into external -and internal organs.

External organs

The external organs are the clitoris, the inner lips, the mons pubis, the vaginal opening and the outer lips. Together they are called the vulva. Its appearance differs from one woman to another.

• The clitoris is a sensitive organ that is important in sexual response. It exists from the tip (glans), two copora cavernosa, a knob of tissue and two crura. They develop before birth and the gender organs of one gender are homologous. The clitoris of the female is homologous to the male’s penis because they exist from the same embryonic tissue. The clitoris is also erectile and fills with blood as the penis does. The clitoris is unique because it has no reproductive function.
• The mons pubis is the rounded and fatty part of tissue covered in pubic hairs.
• The labia is the part along both sides of the opening of the vagina and also covered with pubic hairs. The Bartholin glands lie inside the inner lips and do not have a significant function. The perineum is the area between the anus and the vagina. The introitus is the opening of the vagina itself. Urine does not pass through the clitoris itself, but through the urethra, which is a separate opening.
• The hymen is a thin membrane that partly covers the opening of the vagina. It has some openings for menstrual fluid. It can be opened or stretched when the penis moves into the vagina. The hymen may be taken as a sign of virginity as it typically breaks when first having intercourse. However, a women without a hymen can still be a virgin, some girls are just born without.

Internal organs

The internal organs consist of the vestibular bulbs, the skene’s glands, the vagina, a pair of fallopian tubes and a pair of ovaries.

• The vagina is the organ in which the penis is inserted during sex. It is also referred to as the birth canal or introitus. The cervix at the lower part of the uterus is connected to the top. The walls of the vagina have three layers. The inner part of the vagina is sensitive to erotic stimulation. Around the vagina there is the pubococcygeus muscle, which is stretched during childbirth.
• The vestibular bulbs are two small organs that lie on either side of the vaginal wall.
• The skene’s gland or female prostate lies between the wall of the vagina and the urethra. This organ is the G-spot responsible for female ejaculation.
• The uterus or womb has the cervix which opens into the vagina. The major function is the development of a foetus.
• The fallopian tubes are the pathway by which the sperm reaches the egg.
• The ovaries lie on either side of the uterus and produce the eggs. They also produce estrogen and progesterone. They contain follicles, capsules that surround an egg.

The Breasts

Although they are not sex organs, they have a reproductive and erotic significance. They consist of fifteen to twenty clusters of mammary glands, all with a separate opening to the nipple. They are covered with a fibrous and fatty tissue. The nipple has a lot of nerves and is therefore sensitive to stimulation. The darker area around the nipple is called areola. The symbolical and psychological meaning of the breasts is enormous.

What are the male sexual organs?

The most notable parts of the sexual organs of the male are the scrotum, scrotal sac and the penis.

External organs

• The penis has an important function in reproduction, urination and sexual pleasure. The end or tip is called the glans. The opening at the end is called the meatus or urethral opening. Trough this opening pass urine and semen. The main part is called shaft and the raised ridge is called corona. The corona and the rest of the glans are most sensitive to stimulation. Inside the penis there are the corpora cavernosa and the corpus spongiosum. During the erection these tissues are swollen because they are filled with blood, making the penis stiff. The skin of the penis is usually not covered in hair.

• The foreskin is an additional layer of skin that covers the glans. In some adults this is absent if they are circumcised. Two small glands under the foreskin produce smegma. If the foreskin is not washed properly the smegma hopes up and can start to smell.
• Circumcision is the removal of foreskin. It can be done for religious or cultural reasons and symbolizes the covenant between the Jewish people and god. In Polynesia they use supercision, where they just make a small incision in the foreskin leaving the rest intact. In some tribes they do subincision, which is an incision in the lower side of the penis to the urethra. Urine is then coming from the base of the penis instead of the top.

Internal organs

• The testes or gonads are important in reproduction. They produce sperm and sex hormones, such as testosterone. In the internal structure, the seminiferous tubules are responsible for storing sperm and the interstitial cells produce testosterone. The cresmasteric reflex is the movement of the scrotum. When it is cold the scrotum moves closer to the body and when it is hot it moves further away to remain a constant temperature that is slightly lower than the body temperature.
• The male germ cells go through several stages of maturation: the spermatogonium, spermatocyte with spermatid as final stage. The sperm passes out of the testes into a single tube, the epididymis. While ejaculating, the sperm moves through vas deferens to the ejaculatory duct, which opens in the urethra. The sperm is then ejaculated out of the penis. The seminal vesticles are two structures that look like a sac and lie above the prostate. They produce about sixty percent of the seminal fluid or ejaculate. The other forty percent is created by the prostate.
• The prostate is situated below the bladder. It exists from glandular tissue and muscle. The prostate is small at birth and grows during puberty. It shrinks at old age. Sometimes it grows big enough to infer with urination, a surgical or medicinal procedure is then needed.
• Cowper’s glands or bulbourethral glands are just below the prostate. They empty into the urethra. The function is to neutralize the acidic urethra which allows safe passage of the sperm.

What kind of cancer exists in sex organs?

There are several kinds of cancer people can have in their sex organs. There is breast cancer, cancer of the cervix, endometrium -and ovaries, cancer of the prostate and cancer of the testes.

Breast cancer

This is the most common form of cancer in women. About five to ten percent is genetic. Other risk factors are long-term use of menopausal hormone therapy (MHT) and obesity. Self-exams of breasts can help to detect changes in an early stage. There are three kinds of breast lumps: cysts, fibroadenomas and malignant tumours. About eighty percent of lumps in breasts are not malignant. The technique used for early detection of breast cancer is mammography, also MRI scans can be used, but only recommended for high-risk cases. There are several forms of treatment including lumpectomy and radical mastectomy.

1. Lumpectomy is a surgical treatment where only the lump and surrounding tissue are removed.
2. Radical mastectomy is a surgical treatment where the entire breast is removed.

Both techniques have psychological consequences. The emotional response is often depression and anxiety. Relationship tensions can increase. However, most women show posttraumatic growth when they learn to live with their new body. Cognitive behavioural therapy can be useful in treatment of emotional responses to breast cancer.

Cancer of the cervix, endometrium and ovaries

About ninety-five percent of this type of cancer is caused by the HPV virus. Early heterosexual intercourse and multiple are known risk-factors. HPV interferes with the tumour suppressor genes. A pap test can detect this type of cancer early and helps to decrease the death rate. Diagnosis is difficult due to the varying symptoms. The symptoms such as vomiting and cramping can be related to many less serious conditions. Treatment, when detected early is cryotherapy that uses extreme cold to destroy the abnormal cells. For women with advanced cervical cancer, hysterectomy is used. This is the removal of the uterus. The vagina is left intact, so intercourse is quite possible.

Cancer of the prostate

Most cases of prostate cancer are not lethal. Most tumors are small and not widespread. The prostate cancer gene is called HPC1, but only accounts for three percent of the cases. Symptoms are frequent urination (especially at night), difficulties in urinating and prostate enlargement. The tumour presses onto the urethra causing these symptoms. In the beginning the disease may give a men frequent erections and increase in sex drive which results in problems with sexual functioning as the disease progresses. Rectal examination is the simple and best way for preliminary diagnosis. Treatment involves surgical removal of the prostate. Surgery can result in erection problems. The risk for prostate cancer increases with the number of sex partners.

Cancer of the testes

This is not a common form of cancer. It tends to happen to young men between the age of twenty-nine and thirty-five. The first sign is change in consistency of the testes or a painless lump. Many men do not discover the tumour. When the lump is early detected the survival rate is almost a hundred percent. When the tumour develops this is only seventy percent. Final diagnosis involves surgical removal of the testes. The other testicle can remain so hormone production and functioning can continue normally.

Summary: Chapter 4 – Sexual anatomy

• The female sexual organs are divided into external -and internal organs. The external organs are the clitoris, the inner lips, the mons pubis, the vaginal opening and the outer lips. Together they are called the vulva. Its appearance differs from one woman to another.
• The most notable parts of the sexual organs of the male are the scrotum, scrotal sac and the penis.
• Circumcision is the removal of foreskin. It can be done for religious or cultural reasons and symbolizes the covenant between the Jewish people and god.

Study note: Chapter 4 – Sexual anatomy

• Make sure you can name the most important internal and external organs of the female sexual anatomy
• Make sure you can name the most important internal and external organs of the male sexual anatomy
• What could be the psychological consequence of the treatment of different types of cancer on someone’s sexual functioning?

Chapter 5 - Sex hormones, sexual differentiation and the menstrual cycle

During the prenatal period most differences between men and women arise. This complex process is named: parental sexual differentiation. In this chapter the process of the menstrual cycle and sexual differentiation is discussed.

What are sex hormones?

The chemical substances that are created by the endocrine glands and secreted into the bloodstream are called hormones. The effects of hormones are felt rapidly through its secretion into the bloodstream. The hormones that are most important for sex are the following:

• Testosterone, this hormone belongs to the group called androgens.
• Oestrogens
• Progesterone

The endocrine glands that are of interest are those for sex, these are the testes in males and the ovaries in females. The pituitary gland is related to the hypothalamus. The hypothalamus regulates the pituitary, which regulates the ovaries and the testes. Therefore, it has the nickname of master gland. The hypothalamus plays a role in vital behaviours such as drinking, easting and having sex. The pituitary, hypothalamus and gonads (which are the ovaries and testes) work together to regulate the functions needed for sex.

What are sex hormone systems in males?

Both the testes and the pituitary produce hormones, the most important one in men is testosterone. It has a function in maintaining and stimulating the secondary characteristics of sex, such as beard growth. It also is responsible for maintaining genitals and their production of sperm and for stimulation of the bones and muscles. The pituitary produces two important hormones, both hormones influence the functioning of the testes.

1. Follicle stimulating hormone (FSH): controls sperm production.
2. Luteinizing hormone (LH): controls testosterone production.

Because of the negative feedback loop between the pituitary, the testes and the hypothalamus, the testosterone levels in males remain relatively constant. The level of the LH and FSH hormone is regulated bygonadotropin-releasing hormone or GnRH. This hormone is secreted by the hypothalamus. The feedback loop, where the hypothalamus monitors the testosterone levels and influences the level of GnRH, is called the HPG-axis. When testosterone levels are high, the hypothalamus produces GnRH to make sure the pituitary stops producing as much LH. This negative feedback loop is important for keeping the testosterone level constant. The hormone inhibin is produced by the Sertoli cells in the testes. It regulates FSH in a negative feedback loop, inhibin suppresses FSH, which suppresses sperm production. The hormone shows great potential to serve as a male anticonception method.

What are sex hormone systems in females?

Oestrogen and progesterone are the hormones produced by the ovaries. Oestrogen is responsible for the changes in puberty. It stimulates the growth of the vagina, uterus, pelvis and breasts. It also regulates membranes of the vagina and stops muscle and bone growth in females. The levels of these hormones fluctuate during pregnancy, menopause and the menstrual cycle. The two hormones produced by the pituitary, LH and FSH regulate the levels of progesterone and oestrogen. They are also controlled by the negative feedback loop of the hypothalamus, like the negative feedback loop for testosterone in men. Inhibin is produced by the ovaries instead of the testes. Besides this, the pituitary produces two other hormones: prolactin and oxytocin. The first is responsible for the production of milk after the pregnancy and the second stimulates the contractions of the uterus during childbirth. After birth, oxytocin seems to promote bonding with the child.

What are prenatal sexual differences?

Sex chromosomes

A new human starts from a single cell and develops into a male or female. The specific chromosomes within that cell determine its gender. Two X chromosomes is typically a woman, an X and Y chromosome becomes a man. These chromosomes give instructions on which organs to develop. Some children are born with a different combination. This often results in the Klinefelter syndrome. A genetic male has the XXY chromosomes. Testosterone levels are low and there is no sperm being produced. The single cell duplicates many times during growth and turns into an embryo. By the seventh week you can tell whether it’s a male or female.

Gonads

After the seventh week, differentiation of the sex chromosomes begins. One important gene involved in differentiation is the SRY-gene, or sex-determining region, Y chromosome. This gene is responsible for the testes-determining factor (TDF). The X chromosome consists of genes that control ovary functions.

Prenatal hormones and the genitals

After differentiation, the sex hormones are produced and cause changes in the internal and external genitals. In females, the Mullerian ducts become fallopian tubes, the vagina and the uterus. The tubercle changes into the clitoris, inner -and outer lips. In men, the Wolffian ducts turn into the ejaculatory duct, the vas deferens and the epididymis. The tubercle becomes the glans of the penis and the scrotum.

Descent of the testes and ovaries

While these differentiations take place, the testes and ovaries change position and shape. Before shifting to the final position in the pelvis they remain at the upper end. The testes undergo a similar change going through the inguinal canal. There are two issues that can occur during this process:

1. Cryptorchidism meaning undescended testes
2. Inguinal hernia meaning an unfinished inguinal canal

Brain differentiation

Aside from differentiation in the genitals, there is also brain differentiation. Epigenetics refers to changes in DNA that does not alter the DNA code, but rather leads to changes in the expression of specific genes. Genes responsible for brain differentiation can be found in several genes. New studies using MRI reveal important insights in the androgen and oestrogen receptors responsible for gender differences. Studying the brain using fMRI revealed that there is an activation of a region in the hypothalamus in men when they were sexually aroused. Neuroscientists emphasize the brain’s plasticity and argue that is continuously changing in response to certain experiences.

Homologous organs

Men and women have the same origins and develop the same embryonic tissue. The organs are called homologous. When two organs have a similar function, they are referred to as analogous.

What are atypical differences between genders?

There are several variables of gender (Money, 1987) they are the following:

1. Chromosomal gender. This is XY in males and XX in females.
2. Gonadal gender. These are testes in men and ovaries in women.
3. Prenatal hormonal gender and prenatal and neonatal brain differentiation. The existence of MIS and testosterone in men, but not in women before birth. Testosterone is present for masculinization.
4. Internal organs. These include the uterus, the upper vagina, the fallopian tubes, the prostate, vas and seminal vesicles.
5. Externa genital appearance. This are the inner and outer lips, the clitoris, the vaginal opening, the scrotum and the penis.
6. Pubertal hormonal gender. Testosterone, oestrogen and progesterone.
7. Assigned gender. The announcement whether it is a boy or a girl.
8. Gender identity. The internal sense of female -or maleness.

A person is said to have an intersex condition or disorder of sex development when there are contradictions between several of the above biological factors (1 to 6). There are several syndromes that can cause an intersex condition. One is congenital adrenal hyperplasia, this is when a genetic female produces an excess number of androgens during prenatal sexual differentiation. The external genitals will then appear men. Another condition is androgen-insensitivity syndrome where a male develops normally including its testosterone levels, however the body is insensitive to them. This results in a feminized sexual development. The person is born with the external organs of a female.

What sexual differentiation happens during puberty?

The scientific definition of puberty is the period of sudden maturation and enlargement of the gonads, secondary sex characteristics and other genitalia leading to the capacity to reproduce. The psychological process that people endure during puberty is a result of increased hormone activity. Adolescence is defined as the period of transformation of behaviour, responsibilities and attitudes to become an adult. The timing for pubertal processes is very different between males and females. Boys begin about two years later than girls, who start around the twelfth year of age. Also, there are large individual differences in the age when puberty begins.

Changes in girls

The first sign of puberty in girls is breast development. This starts when a girl is about eight or nine years old. The changes are produced by increases in sex hormone levels. Besides the growth of the breast, another visible sign is the growth of pubic -and underarm (armpit) hair. Oestrogen is responsible for stopping the growth spurt in girls and causes the growth period to be shorter than in boys. The menarchehappens around the age of twelve and is the first time of menstruation. There are some factors that contribute to the age of the menarche. One is body fat, leptin is the hormone that determines the onset of puberty and rises with body fat. Kisspeptin is another hormone to stimulate the onset of puberty. It does so by stimulating the hypothalamus to secrete is sex-hormone GnRH and later LH and FSH. The influence of body fat is important in describing two phenomena:

1. The cessation of menstruation in girls with anorexia nervosa.
2. The cessation of menstruation in runners or extreme athletes.

The adrenal glands are also important in puberty. They produce androgens that stimulate pubic -and axillary hair growth. It is also related to female sex drive. The adrenarche is the onset of increasing secretion of the adrenal androgens. The adrenarche is mostly around eight years.

Changes in boys

Puberty starts later in boys and begins with heightened levels of the hormones: LH and FSH. The first sign is growth of the scrotum and testes. Pubic hair growth starts about the same age, around nine. One year later the penis starts to grow, which is caused by testosterone stimulation. Erections increase in frequency and when a boy is around thirteen or fourteen years old, he can ejaculate. One year later, boys start having nocturnal emissions and for a boy that has never masturbated, that can be his first ejaculation. In boys, acne is quite normal during puberty cause by androgens. It is a shame that there is so little interest in the rites of passage for both boys and girls when they enter the stage of puberty. When there is more recognition, boys and girls might better understand the stage they are in.

How does the menstrual cycle work?

Fluctuating hormones in the body regulate the menstrual cycle. There are several phases involved in the menstrual cycle which are all characterized by different hormones.

1. The follicular phase is when high levels of FSH are secreted. This causes an egg to get to the state of final maturity. Oestrogen is secreted at the same time.
2. The ovulation is when the mature egg is released by the follicle. Oestrogen is risen to a level where it inhibits the secretion of FSH and increase produce of GnRH, which causes beginning of production of LH.
3. The luteal phase is when the follicle (caused by LH) turns into a corpus luteum. It manufactures progesterone and inhibits LH secretion causing the corpus luteum to degenerate. After this a sharp decrease of oestrogen and progesterone causes the stimulation of FSH and the cycle can be repeated.
4. The menstruation is when the inner lining of the uterus is passed out through the vagina. During this phase, FSH levels are rising, oestrogen and progesterone levels are low. These low levels of oestrogen and progesterone trigger the menstruation and end the luteal phase.

The menstrual cycle lasts from twenty to thirty-six days with an average of twenty-eight days. There can be menstrual problems, for example dysmenorrhea is the most common and is the experience of a painful menstruation. It is caused by prostaflandis, a hormone causing muscle contraction. The best treatment is NSAIDs or nonsteroidal anti-inflammatory drugs. Another proposed cure is masturbation because the discomfort is caused by the pelvic edema, which increases during an orgasm. The second problem is endometrosis, caused by growth of the endometrium. It should be treated by a physician, otherwise it can lead to sterility. The last menstrual problem is amenorrhea, which is the absence of menstruation.

What are the psychological aspects of the menstrual cycle?

• Fluctuation in mood is related to the premenstrual syndrome (PMS). It is the occurrence of psychological and physical symptoms that occur prior to menstruation. Symptoms are breast pain, water retention and depression and irritability. Researchers showed that only sadness and irritability showed significant changes throughout the menstrual cycle. It was not just prior to menstruation, which is the main concept of PMS. There is no scientific evidence of PMS. There is a premenstrual dysphoric disorder (PMDD) which is found in a small percentage of women. Symptoms are feelings of hopelessness, sadness, anxiety, fearfulness and tension in the luteal phase.  
• Fluctuations in performance can be a practical indicator of mood changes during the menstrual cycle. Researchers did not find any fluctuations in performance, there is no reliable evidence of performance decrease caused by the menstrual cycle.
• Fluctuations in sex drive, there is a link between sex drive and menstruation and is associated with the testosterone levels. Therefore, women have a peak in sexuality while ovulating.

Summary: Chapter 5 - Sex hormones, sexual differentiation and the menstrual cycle

• During the prenatal period most differences between men and women arise. This complex process is named: parental sexual differentiation.
• A new human starts from a single cell and develops into a male or female. The specific chromosomes within that cell determine its gender. Two X chromosomes is typically a woman, an X and Y chromosome becomes a man. These chromosomes give instructions on which organs to develop.
• Aside from differentiation in the genitals, there is also brain differentiation. Epigenetics refers to changes in DNA that does not alter the DNA code, but rather leads to changes in the expression of specific genes. Genes responsible for brain differentiation can be found in several genes.

Study note: Chapter 5 - Sex hormones, sexual differentiation and the menstrual cycle

• Make sure you know the most important hormones that are important for puberty and sexual differentiation.
• The female changes of breast development and menarche, and changes in men which include growth of the penis and testes and beginning of ejaculation are important concepts described in this chapter.
• Women often complain about PMS. However, this has never been scientifically proven. Could you think of reasons of why people still believe in the existence of PMS?