Historical perspectives such as those offered by Glen Elder, Joseph Kett, or Thomas Hine stress the fact that adolescence as a developmental period has varied considerably from one historical era to another. Because of its ever-changing nature, it is impossible to generalize about issues such as the degree to which adolescence is stressful, the developmental tasks of the period, or the nature of intergenerational relationships. One group of theorists, called inventionists, argue that adolescence is entirely a social invention, and that the way in which we divide the life cycle into stages is nothing more than a reflection of the political, economic and social circumstances in which we live. According to this group, although puberty has been a feature of development for as long as humans have lived, it was not until the rise of obligatory education that we began treating adolescents as a distinct group.
[17]
[edit]Biological development
[edit]Puberty
[edit]General

Upper body of teenage boy. The structure has changed to resemble an
adult form.
Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The average onset of puberty is at 10 or 11 for girls and age 12 or 13 for boys.
[18][19] Every person's individual timetable for puberty is influenced primarily by
heredity, although environmental factors, such as diet and exercise, also exert some influence.
[18][20][21] These factors can also contribute to
precocious and
delayed puberty.
[13][21]
Some of the most significant parts of pubertal development involve distinctive physiological changes in individuals' height, weight, body composition, and
circulatory and
respiratory systems.
[22] These changes are largely influenced by hormonal activity. Hormones play an organizational role, priming the body to behave in a certain way once puberty begins,
[23] and an activational role, referring to changes in hormones during adolescence that trigger behavioral and physical changes.
[24]
Puberty begins with a surge in hormone production, which in turn causes a number of physical changes.
[18] It is also the stage of life in which a
child develops
secondary sex characteristics (for example, a deeper voice and larger
adam's apple in boys, and development of
breasts and more curved and prominent
hips in girls) as his or her hormonal balance shifts strongly towards an adult state. This is triggered by the
pituitary gland, which secretes a surge of
hormonal agents into the blood stream, initiating a chain reaction. The male and female
gonads are subsequently activated, which puts them into a state of rapid growth and development; the triggered gonads now commence the mass production of the necessary
chemicals. The testes primarily release
testosterone, and the ovaries predominantly dispense
estrogen. The production of these hormones increases gradually until sexual maturation is met. Some boys may develop
gynecomastia due to an imbalance of
sex hormones, tissue responsiveness or
obesity.
[25][26]
Facial hair in males normally appears in a specific order during puberty: The first facial hair to appear tends to grow at the corners of the upper lip, typically between 14 to 16 years of age.
[27][28] It then spreads to form a
moustache over the entire upper lip. This is followed by the appearance of hair on the upper part of the cheeks, and the area under the lower lip.
[27] The hair eventually spreads to the sides and lower border of the chin, and the rest of the lower face to form a full beard.
[27] As with most human biological processes, this specific order may vary among some individuals. Facial hair is often present in late adolescence, around ages 17 and 18, but may not appear until significantly later.
[28][29] Some men do not develop full facial hair for 10 years after puberty.
[28] Facial hair will continue to get coarser, darker and thicker for another 2–4 years after puberty.
[28]
The major landmark of puberty for males is the first
ejaculation, which occurs, on average, at age 13.
[30] For females, it is
menarche, the onset of menstruation, which occurs, on average, between ages 12 and 13.
[20][31][32][33] The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well.
[20] Regardless of genes, a girl must have certain proportion of body fat to attain menarche.
[20]Consequently, girls who have a high-fat diet and who are not physically active begin menstruating earlier, on average, than girls whose diet contains less fat and whose activities involve fat reducing exercise (e.g. ballet and gymnastics).
[20][21] Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages.
[20]
The timing of puberty can have important psychological and social consequences. Early maturing boys are usually taller and stronger than their friends.
[34] They have the advantage in capturing the attention of potential partners and in becoming hand-picked for sports. Pubescent boys often tend to have a good body image, are more confident, secure, and more independent.
[35] Late maturing boys can be less confident because of poor body image when comparing themselves to already developed friends and peers. However, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to the surge of hormones that affect them.
[35] Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, despite the fact that their
cognitive and
social development may lag behind their appearance.
[35] Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.
[36]
For girls early maturation can sometimes lead to increased self-consciousness, though a typical aspect in maturing females.
[37] Because of their bodies' developing in advance, pubescent girls can become more insecure.
[37] Consequently, girls that reach sexual maturation early are more likely than their peers to develop eating disorders. Nearly half of all American high school girls' diet is to lose weight.
[37] In addition, girls may have to deal with sexual advances from older boys before they are emotionally and mentally mature.
[38] In addition to having earlier sexual experiences and more unwanted pregnancies than late maturing girls, early maturing girls are more exposed to
alcohol and
drug abuse.
[39] Those who have had such experiences tend to perform less well in school than their "inexperienced" age peers.
[40]
Girls have usually reached full physical development by ages 15–17,
[2][41][19] while boys usually complete puberty by ages 16–18.
[41][19][42]Any increase in height beyond the post-pubertal age is uncommon. Girls attain reproductive maturity about 4 years after the first physical changes of puberty appear.
[2] In contrast, boys accelerate more slowly but continue to grow for about 6 years after the first visible pubertal changes.
[35][42]

Approximate outline of development periods in
child and teenager development. Adolescence is marked in red at top right.
[edit]Growth spurt
The adolescent growth spurt is a rapid increase in individuals'
height and weight during puberty resulting from the simultaneous release of growth hormones,
thyroid hormones, and
androgens.
[43] Males experience their growth spurt about two years later, on average, than females. During their peak height velocity (the time of most rapid growth), adolescents grow at a growth rate nearly identical to that of a toddler—about 4 inches (10.3 cm) a year for males and 3.5 inches (9 cm) for females.
[44] In addition to changes in height, adolescents also experience a significant increase in weight (Marshall, 1978). The weight gained during adolescence constitutes nearly half of one's adult body weight.
[44]Teenage and early adult males may continue to gain natural muscle growth even after puberty.
[35]
The accelerated growth in different body parts happens at different times, but for all adolescents it has a fairly regular sequence. The first places to grow are the extremities—the head, hands and feet—followed by the arms and legs, then the torso and shoulders.
[45] This non-uniform growth is one reason why an adolescent body may seem to be out of proportion.
During puberty, bones become harder and more brittle. At the conclusion of puberty, the ends of the long bones close during the process called
epiphysis. There are ethnic differences in these skeletal changes: bone density increases significantly more among African-American than white adolescents, which might account for decreased likelihood of African-American women developing
osteoporosis and having fewer bone fractures.
[46]
Another set of significant physical changes during puberty happen in bodily distribution of fat and muscle. This process is different for females and males. Before puberty, there are nearly no sex differences in fat and muscle distribution; during puberty, boys grow muscle much faster than girls, although both sexes experience rapid muscle development. In contrast, though both sexes experience an increase in body fat, the increase much more significant for girls. Frequently, the increase in fat for girls happens in their years just before puberty. The ratio between muscle and fat among post-pubertal boys is around three to one, while for girls it is about five to four. This may help explain sex differences in athletic performance.
[47]
Pubertal development also affects
circulatory and
respiratory systems as an adolescents' heart and lungs increase in both size and capacity. These changes lead to increased strength and tolerance for exercise. Sex differences are apparent as males tend to develop "larger hearts and lungs, higher systolic blood pressure, a lower resting heart rate, a greater capacity for carrying oxygen to the blood, a greater power for neutralizing the chemical products of muscular exercise, higher blood hemoglobin and more red blood cells".
[48]
It is important to note that, despite some genetic sex differences, environmental factors play a large role in biological changes during adolescence. For example, girls tend to reduce their physical activity in preadolescence
[49][50] and may receive inadequate nutrition from diets that often lack important nutrients, such as iron.
[51] These environmental influences in turn affect female physical development.
[edit]Reproduction-related changes
Primary sex characteristics are those directly related to the sex organs. In males, the first stages of puberty involve growth of the testes and scrotum, followed by growth of the penis.
[52] At the time that the penis develops, the seminal vesicles, the prostate, and the bilbo-urethral glands also enlarge and develop. The first ejaculation of seminal fluid generally occurs about one year after the beginning of accelerated penis growth, although this is often determined culturally rather than biologically, since for many boys first ejaculation occurs as a result of masturbation.
[45] Boys are generally fertile before they have an adult appearance
[43]
In females, changes in the primary sex characteristics involve growth of the uterus, vagina, and other aspects of the reproductive system.
Menarche, the beginning of menstruation, is a relatively late development which follows a long series of hormonal changes.
[53] Generally, a girl is not fully fertile until several years after menarche, as regular ovulation follows menarche by about two years.
[54] Unlike males, therefore, females usually appear physically mature before they are capable of becoming pregnant.
Changes in
secondary sex characteristics include every change that is not directly related to sexual reproduction. In males, these changes involve appearance of pubic, facial, and body hair, deepening of the voice, roughening of the skin around the upper arms and thighs, and increased development of the sweat glands. In females, secondary sex changes involve elevation of the breast, widening of the hips, development of pubic and underarm hair, widening of the areolae, and elevation of the nipples.
[55]
The changes in secondary sex characteristics that take place during puberty are often referred to in terms of five
Tanner stages,
[56] named after the British pediatrician who devised the categorization system.
[edit]Changes in the brain
The human brain is not fully developed by the time a person reaches puberty. Between the ages of 10 and 25, the brain undergoes changes that have important implications for behavior (see
Cognitive development below).
The brain reaches 90% of its adult size by the time a person is six years of age.
[57] Thus, the brain does not grow in size much during adolescence. However, the creases in the brain continue to become more complex until the late teens. The biggest changes in the folds of the brain during this time occur in the parts of the cortex that process cognitive and emotional information.
[57]
Over the course of adolescence, the amount of
white matter in the brain increases linearly, while the amount of
grey matter in the brain follows an inverted-U pattern. Through a process called
synaptic pruning, unnecessary neuronal connections in the brain are eliminated and the amount of grey matter is pared down. However, this does not mean that the brain loses functionality; rather, it becomes more efficient due to increased
myelination (insulation of axons) and the reduction of unused pathways.
[58]
The first areas of the brain to be pruned are those involving primary functions, such as motor and sensory areas. The areas of the brain involved in more complex processes lose matter later in development. These include the lateral and
prefrontal cortices, among other regions.
[59]
Some of the most developmentally significant changes in the brain occur in the
prefrontal cortex, which is involved in
decision-making and cognitive control, as well as other higher cognitive functions. During adolescence, myelination and synaptic pruning in the prefrontal cortex increases, improving the efficiency of information processing, and neural connections between the prefrontal cortex and other regions of the brain are strengthened.
[60] This leads to better evaluation of risks and rewards, as well as improved control over impulses. Specifically, developments in the dorsolateral prefrontal cortex are important for controlling impulses and planning ahead, while development in the ventromedial prefrontal cortex is important for decision making. Changes in the orbitofrontal cortex are important for evaluating rewards and risks.
Two
neurotransmitters that play important roles in adolescent brain development are
glutamate and
dopamine. Glutamate is an excitatory neurotransmitter. During the synaptic pruning that occurs during adolescence, most of the neural connections that are pruned contain receptors for glutamate or other excitatory neurotransmitters.
[61] Because of this, by early adulthood the synaptic balance in the brain is more inhibitory than excitatory.
Dopamine is associated with pleasure and attuning to the environment during decision-making. During adolescence, dopamine levels in the
limbic system increase and input of dopamine to the prefrontal cortex increases.
[62] The balance of excitatory to inhibitory neurotransmitters and increased dopamine activity in adolescence may have implications for adolescent risk-taking and vulnerability to boredom (see
Cognitive development, below). Development in the
limbic system plays an important role in determining rewards and punishments and processing emotional experience and social information. Changes in the levels of the neurotransmitters
dopamine and
serotonin in the limbic system make adolescents more emotional and more responsive to rewards and stress. The corresponding increase in emotional variability also can increase adolescents’ vulnerability.
[edit]Cognitive development
Adolescence is also a time for rapid cognitive development.
[63] Piaget describes adolescence as the stage of life in which the individual's thoughts start taking more of an abstract form and the egocentric thoughts decrease. This allows the individual to think and reason in a wider perspective.
[64] A combination of behavioural and
fMRI studies have demonstrated development of
executive functions, that is, cognitive skills that enable the control and coordination of thoughts and behaviour, which are generally associated with the
prefrontal cortex.
[65] The thoughts, ideas and concepts developed at this period of life greatly influence one's future life, playing a major role in character and personality formation.
[66]
Biological changes in brain structure and connectivity within the brain interact with increased experience, knowledge, and changing social demands to produce rapid cognitive growth (see
Changes in the brain above). The age at which particular changes take place will vary between individuals, but the changes discussed below generally begin at puberty or shortly thereafter and some skills continue to develop as the adolescent ages.
[edit]Theoretical perspectives
There are two perspectives on adolescent thinking. One is the
constructivist view of cognitive development. Based on the work of
Piaget, it takes a quantitative, state-theory approach, hypothesizing that adolescents’ cognitive improvement is relatively sudden and drastic. The second is the
information-processing perspective, which derives from the study of artificial intelligence and attempts to explain cognitive development in terms of the growth of specific components of the thinking process.
[edit]Improvements in cognitive ability
By the time individuals have reached age 15 or so, their basic thinking abilities are comparable to those of adults. These improvements occur in five areas during adolescence:
- Attention. Improvements are seen in selective attention, the process by which one focuses on one stimulus while tuning out another.Divided attention, the ability to pay attention to two or more stimuli at the same time, also improves.[67][68]
- Memory. Improvements are seen in both working memory and long-term memory.[69]
- Processing speed. Adolescents think more quickly than children. Processing speed improves sharply between age five and middle adolescence; it then begins to level off at age 15 and does not appear to change between late adolescence and adulthood.[70]
- Organization. Adolescents are more aware of their own thought processes and can use mnemonic devices and other strategies to think more efficiently.[71]
- Metacognition.
[edit]Hypothetical and abstract thinking
Adolescents' thinking is less bound to concrete events than that of children: they can contemplate possibilities outside the realm of what currently exists. One manifestation of the adolescent’s increased facility with thinking about possibilities is the improvement of skill in
deductive reasoning, which leads to the development of hypothetical thinking. This provides the ability to plan ahead, see the future consequences of an action and to provide alternative explanations of events. It also makes adolescents more skilled debaters, as they can reason against a friend’s or parent’s assumptions. Adolescents also develop a more sophisticated understanding of probability.
The appearance of more systematic, abstract thinking is another notable aspect of cognitive development during adolescence. For example, adolescents find it easier than children to comprehend the sorts of higher-order abstract logic inherent in puns, proverbs, metaphors, and analogies. Their increased facility permits them to appreciate the ways in which language can be used to convey multiple messages, such as satire, metaphor, and sarcasm. (Children younger than age nine often cannot comprehend sarcasm at all).
[72] This also permits the application of advanced reasoning and logical processes to social and ideological matters such as interpersonal relationships, politics, philosophy, religion, morality, friendship, faith, democracy, fairness, and honesty.
[edit]Metacognition
A third gain in cognitive ability involves thinking about thinking itself, a process referred to as
metacognition. It often involves monitoring one’s own cognitive activity during the thinking process. Adolescents’ improvements in knowledge of their own thinking patterns lead to better self-control and more effective studying. It is also relevant in social cognition, resulting in increased
introspection,
self-consciousness, and intellectualization (in the sense of thought about one’s own thoughts, rather than the Freudian definition as a defense mechanism). Adolescents are much better able than children to understand that people do not have complete control over their mental activity. Being able to introspect may lead to two forms of adolescent egocentrism, which results in two distinct problems in thinking: the
imaginary audience and the
personal fable. These likely peak at age fifteen, along with self-consciousness in general.
[73]
Related to
metacognition and
abstract thought, perspective-taking involves a more sophisticated
theory of mind.
[74] Adolescents reach a stage of social perspective-taking in which they can understand how the thoughts or actions of one person can influence those of another person, even if they personally are not involved.
[75]
[edit]Relativistic thinking
Compared to children, adolescents are more likely to question others’ assertions, and less likely to accept facts as absolute truths. Through experience outside the family circle, they learn that rules they were taught as absolute are in fact relativistic. They begin to differentiate between rules instituted out of common sense—not touching a hot stove—and those that are based on culturally-relative standards (codes of etiquette, not dating until a certain age), a delineation that younger children do not make. This can lead to a period of questioning authority in all domains.
[76]
Wisdom, or the capacity for insight and judgment that is developed through experience,
[77] increases between the ages of fourteen and twenty-five, then levels off. Thus, it is during the adolescence-adulthood transition that individuals acquire the type of wisdom that is associated with age. Wisdom is not the same as intelligence: adolescents do not improve substantially on
IQ tests since their scores are relative to others in their same age group, and relative standing usually does not change—everyone matures at approximately the same rate.
[edit]Risk-taking
In light of the fact that most injuries sustained by adolescents are related to risky behavior (car crashes, alcohol, unprotected sex), much research has been done on adolescent risk-taking, particularly on whether and why adolescents are more likely to take risks than adults. Behavioral decision-making theory says that adolescents and adults both weigh the potential rewards and consequences of an action. However, research has shown that adolescents seem to give more weight to rewards, particularly social rewards, than do adults.
[78]
During adolescence, there is an extremely high emphasis on approval of peers as a reward due to adolescents' increased self-consciousness. There may be evolutionary benefits to an increased propensity for risk-taking in adolescence—without risk-taking, teenagers would not have the motivation or confidence necessary to make the change in society from childhood to adulthood. It may also have reproductive advantages: adolescents have a newfound priority in sexual attraction and dating, and risk-taking is required to impress potential mates. Research also indicates that baseline
sensation seeking may affect risk-taking behavior throughout the lifespan.
[79][80]
[edit]Social development
[edit]Identity development
Among the most common beliefs about adolescence is that it is the time when teens form their personal identities.
Egocentrism is being perfomed by adolescents which then forms self-consciousness of wanting to feel important in their peer groups and having social acceptance of fitting into the group.
[81]. Empirical studies suggest that this process might be more accurately described as identity development, rather than formation, but confirms a normative process of change in both content and structure of one’s thoughts about the self.
[82] Researchers have used three general approaches to understanding identity development: self-concept, sense of identity, and self-esteem.
[edit]Self-concept
Early in adolescence,
cognitive developments result in greater self-awareness, greater awareness of others and their thoughts and judgments, the ability to think about abstract, future possibilities, and the ability to consider multiple possibilities at once. As a result, adolescents experience a significant shift from the simple, concrete, and global self-descriptions typical of young children; as children, they defined themselves with physical traits whereas as adolescents, they define themselves based on their values, thoughts and opinions.
[83]
Adolescents can now conceptualize multiple "possible selves" they could become
[84] and long-term possibilities and consequences of their choices.
[85] Exploring these possibilities may result in abrupt changes in self-presentation as the adolescent chooses or rejects qualities and behaviors, trying to guide the
actual self toward the
ideal self (who the adolescent wishes to be) and away from the feared self (who the adolescent does not want to be). For many, these distinctions are uncomfortable, but they also appear to motivate achievement through behavior consistent with the ideal and distinct from the feared possible selves.
[86][87]
Further distinctions in self-concept, called "differentiation," occur as the adolescent recognizes the contextual influences on their own behavior and the perceptions of others, and begin to qualify their traits when asked to describe themselves.
[88] Differentiation appears to be fully developed by mid-adolescence.
[89] Peaking in the 7th-9th grades, the
personality traits adolescents use to describe themselves refer to specific contexts, and therefore may contradict one another. The recognition of inconsistent content in the self-concept is a common source of distress in these years (see
Cognitive dissonance),
[90] but this distress may benefit adolescents by encouraging structural development.
Differentiation results in organization and integration of the self-concept.
[91][92] The multifaceted self is understood to include several stable, if inconsistent, sets of traits applicable when the individual with different people and circumstances. This includes negative traits and weaknesses, which adolescents can now recognize and qualify: "consistent with this, adolescents who have more complex self-conceptions are less likely to be depressed."
[93][94] Moreover, although only true in some circumstances, differentiated traits are contrasted with “false-self behavior,” which is not representative of the “real” self.
[95] Recognition of the inauthentic indicates that the adolescent is gaining a sense of continuous, overlapping, coherent sense of identity.
[edit]Sense of identity
Unlike the conflicting aspects of self-concept, identity represents a coherent sense of self stable across circumstances and including past experiences and future goals. Everyone has a self-concept, whereas
Erik Erikson argued that not everyone fully achieves identity. Erikson’s theory of
stages of development includes the
identity crisis in which adolescents must explore different possibilities and integrate different parts of themselves before committing to their beliefs. He described the resolution of this process as a stage of “identity achievement” (see Fig. 1) but also stressed that the identity challenge “is never fully resolved once and for all at one point in time.”
[96] Adolescents begin by defining themselves based on their
crowd membership.
Researcher James Marcia developed the current method for testing an individual’s progress along these stages.
[97][98] His questions are divided into three categories: occupation, ideology, and interpersonal relationships. Answers are scored based on extent to which the individual has explored and the degree to which he has made commitments. The result is classification of the individual into a) Identity Diffusion in which all children begin, b) Identity Foreclosure in which commitments are made without the exploration of alternatives, c) Moratorium, or the process of exploration, or d) Identity Achievement in which Moratorium has occurred and resulted in commitments.
[99]
Research since reveals self-examination beginning early in adolescence, but identity achievement rarely occurring before age 18.
[100] The freshman year of college influences identity development significantly, but may actually prolong psychosocial moratorium by encouraging reexamination of previous commitments and further exploration of alternate possibilities without encouraging resolution.
[101] For the most part, evidence has supported Erikson’s stages: each correlates with the personality traits he originally predicted.
[99] Studies also confirm the impermanence of the stages
[102] there is no final endpoint in Identity Development.
[edit]Self-esteem
The final major aspect of identity formation is
self-esteem, one’s thoughts and feelings about one’s self-concept and identity. Contrary to popular belief, there is no empirical evidence for a significant drop in self-esteem over the course of adolescence.
[103] ‘Barometric self-esteem’ fluctuates rapidly and can cause severe distress and anxiety, but baseline self-esteem remains highly stable across adolescence.
[104] The validity of global self-esteem scales has been questioned, and many suggest that more specific scales might reveal more about the adolescent experience.
[105] It is also important to note that the patterns of change in self-esteem differ significantly by gender.
[edit]Relationships
Adolescence marks a rapid change in one’s role within a family. Young children tend to assert themselves forcefully, but are unable to demonstrate much influence over family decisions until early adolescence,
[106] when they are increasingly viewed by parents as equals. When children go through puberty, there is often a significant increase in parent-child conflict and a less cohesive familial bond. Arguments often concern minor issues of control, such as curfew, acceptable clothing, and the adolescent's right to privacy,
[107][108] which adolescents may have previously viewed as issues over which their parents had complete authority.
[109] Parent-adolescent disagreement also increases as friends demonstrate a greater impact on one another, new influences on the adolescent that may be in opposition to parents’ values. Although conflicts betweenn children and parents increase during adolescent, these are just relatively minor issues. Regarding to the important issues in lives, most adolescent still share the same attitudes and values as their parents.
[110]
During childhood, siblings are a source of conflict and frustration as well as a support system.
[111] Adolescence may affect this relationship differently, depending on sibling gender. In same-sex sibling pairs, intimacy peaks during early adolescence, then steadily declines. Mixed-sex siblings pairs act in the opposite way; siblings drift apart during early adolescent years, but experience an increase in intimacy starting at middle adolescence.
[112] Sustaining positive sibling relations can assist adolescents in a number of ways. Siblings are able to act as peers, and may increase one another's sociability and feelings of self-worth. Older siblings can give guidance to younger siblings, although the impact of this can be either positive or negative depending on the activity of the older sibling.
Despite changing family roles during adolescence, the home environment and parents are still important for the behaviors and choices of adolescents.
[113] Adolescents who have a good relationship with their parents are less likely to engage in various risk behaviors, such as smoking, drinking, fighting, and/or unprotected
sexual intercourse.
[113]
Peer groups are especially important during adolescence, a period of development characterized by a dramatic increase in time spent with peers
[114] and a decrease in adult supervision.
[115] Adolescents also associate with friends of the opposite sex much more than in childhood
[116] and tend to identify with larger groups of peers based on shared characteristics.
[117]
Peer groups offer members the opportunity to develop various social skills, such as empathy, sharing and leadership. Peer groups can have positive influences on an individual, for instance on academic motivation and performance, but they can also have negative influences and lead to an increase in experimentation with drugs, drinking, vandalism, and stealing.
[118] Susceptibility to
peer pressure increases during early adolescence, peaks around age 14, and declines thereafter.
[119]
During early adolescence, adolescents often associate in
cliques, exclusive, single-sex groups of peers with whom they are particularly close. Towards late adolescence, cliques often merge into mixed-sex groups as teenagers begin romantically engaging with one another.
[120]Typically, in schools, the most popular boys would participate in achievement-oriented activities, which were highly competitive and aggressive such as, athletics. Likewise, the most popular girls would participate in the most interesting social activities, ranging from skiing to late-night parties. Of course, girls who engaged in these activities had to be physically attractive to compete for the opposite sex's attention. Thus, it became common to attribute competitiveness to boys and attractiveness with girls in clique groups.
[121] These small friend groups break down even further as socialization becomes more couple-oriented. Despite the common notion that cliques are an inherently negative influence, they may help adolescents become socially acclimated and form a stronger sense of identity.
On a larger scale, adolescents often associate with
crowds, groups of individuals who share a common interest or activity. Often, crowd identities may be the basis for stereotyping young people, categorizing them as
jocks,
nerds, and so on. In large, multi-ethnic high schools, there are often ethnically-determined crowds as well.
[122] While crowds are very influential during early and middle adolescence, they lose salience during high school as students identify more individually.
[123]
While peers may facilitate social development for one another, they may also hinder it. Both
physical and
relational aggression are linked to a vast number of enduring psychological difficulties, especially depression, as is
social rejection.
[124] Because of this, bullied adolescents often develop problems that lead to further victimization.
[125]
[edit]Romance and sexual activity
Romantic relationships tend to increase in prevalence throughout adolescence. By age 15, 53% of adolescents have had a romantic relationship that lasted at least one month over the course of the previous 18 months.
[126] In a 2008 study conducted by
YouGov for
Channel 4, 20% of 14−17-year-olds surveyed revealed that they had their first sexual experience at 13 or under in the
United Kingdom.
[127] A 2002 American study found that those aged 15–44 reported that the average age of first sexual intercourse was 17.0 for males and 17.3 for females.
[128] The typical duration of relationships increases throughout the teenage years as well. This constant increase in the likelihood of a long-term relationship can be explained by
sexual maturation and the development of cognitive skills necessary to maintain a romantic bond (e.g. caregiving, appropriate attachment), although these skills are not strongly developed until late adolescence.
[129] Long-term relationships allow adolescents to gain the skills necessary for high-quality relationships later in life
[130] and develop feelings of self-worth. Overall, positive romantic relationships among adolescents can result in long-term benefits. High-quality romantic relationships are associated with higher commitment in early adulthood
[131] and are positively associated with self-esteem, self-confidence, and social competence.
[132][133]
The
age of consent to sexual activity varies widely among international jurisdictions, ranging from 12 to 21 years.
[134] Adolescents often date within their demographic in regards to race, ethnicity, popularity, and physical attractiveness.
[135] However, there are traits in which certain individuals, particularly adolescent girls, seek diversity. While most adolescents date people approximately their own age, boys typically date partners the same age or younger; girls typically date partners the same age or older.
[126]
Dating violence is fairly prevalent within adolescent relationships. When surveyed, 10-45% of adolescents reported having experiencing physical violence in the context of a relationship while one-third to a quarter of adolescents reported having experiencing psychological aggression. This reported aggression includes hitting, throwing things, or slaps, although most of this physical aggression does not result in a medical visit. Physical aggression in relationships tends to decline from high school through college and young adulthood. By their early twenties, many fewer romantic couple engage in physical aggression, and aggressors tend to be much more deviant.
[136] In heterosexual couples, there is no significant difference between the rates of male and female aggressors, a surprising finding considering the common assumption that males are more aggressive overall.
[137][138][139] Despite these jarring statistics,
nurturant parenting style is associated with lower rates of relationship violence.
[140]
Adolescence marks a time of sexual maturation, which manifests in social interactions as well. While adolescents may engage in
casual sexual encounters (often referred to as hookups), most sexual experience during this period of development takes place within romantic relationships.
[141] Kissing, hand holding, and hugging signify satisfaction and commitment. Among young adolescents, "heavy" sexual activity, marked by genital stimulation, is often associated with violence, depression, and poor relationship quality.
[142][143] This effect does not hold true for sexual activity in late adolescence that takes place within a romantic relationship.
[144]
Adolescent sexuality refers to sexual feelings,
behavior and development in adolescents and is a stage of human sexuality. Sexuality and sexual desire usually begins to intensify along with the onset of
puberty. The expression of sexual desire among adolescents (or anyone, for that matter), might be influenced by family values and the culture and religion they have grown up in (or as a backlash to such),
social engineering,
social control,
taboos, and other kinds of
social mores.
In contemporary society, adolescents also face some risks as their sexuality begins to transform. Whilst some of these such as emotional distress (fear of abuse or exploitation) and
sexually transmitted diseases (including
HIV/
AIDS) are not necessarily inherent to adolescence, others such as
pregnancy (through non-use or failure of contraceptives) are seen as social problems in most western societies. In terms of
sexual identity, while all
sexual orientations found in adults are also represented among adolescents, statistically the
suicide rate amongst
LGBT adolescents is up to four times higher than that of their heterosexual peers.
[145]
According to anthropologist
Margaret Mead and psychologist
Albert Bandura,
[citation needed] the turmoil found in adolescence in Western society has a cultural rather than a physical cause; they reported that societies where young women engaged in free sexual activity had no such adolescent turmoil.
[edit]Culture
In commerce, this generation (21st century adolescence) is seen as an important target. Mobile phones, electronic devices, contemporary popular music, movies, television programs, websites, sports, video games and clothes are heavily marketed and often popular amongst adolescents. There are also many different ways of viewing adolescence that are prevalent in the world today.
[edit]Sexuality
There are many cultural and socio-economic differences which influence how adolescents' sexuality develops. Menarche (the first menstrual period of a female-bodied person’s life) is, for many cultures, the defining point for the beginning of a transition into adulthood. The age of menarche varies from culture to culture. Girls from countries where menarche/menstruation is seen as an important event, or where there is an ambivalence towards it, tend to have more negative opinions about it.
[146][147] An adolescent’s sexual socialization is highly dependent upon the society they live in, and how restrictive or permissive that society is when it comes to sexual activity.
Restrictive societies “pressure youngsters to refrain from sexual activity until they either have undergone a formal rite of passage or have married.”
[148] Therefore the sexual transition of adolescence is highly discontinuous because there is little preparation for an adult sexuality.
[148] These cultures either control adolescence by separating the males and females throughout their development, or they restrict sexual activity through public shaming and physical punishment.
[149]
In semi-restrictive societies, adults do not condone sexual activity however often do not take strong steps towards restricting it. “Premarital promiscuity is common, and the parents do not object as long as the love affairs are kept secret.”
[149] While some media portrays the United States as a permissive society, adults frequently try to discourage sexual activity among adolescence. This is most obvious among adolescence women because it is premarital pregnancy, rather than premarital sex that is highly objectionable in the United States.
[150] It is also common for adults to lecture women about sex and the importance of virginity by telling them that females do not need sex as much as males do.
[151] Despite these attempts to reduce sexual promiscuity, parents in the United States and other semi-restrictive societies do not prohibit young men and women from interacting both in social and private settings.
In permissive societies, the transition into sexual adulthood is highly continuous and begins at an early age.
[150] Some examples of sexually permissive societies are the Pukapukans of Polynesia and Trobiand girls and boys.
[150] In the Pukapukans society, parent simply ignore any sexual activity among children even when they are masturbating freely and openly in public. In the Trobiand society, young girls and boys participate in oral stimulation as a means of amusement and are encourage to participate in sexual activity with other young girls and boys at any time, they are encouraged to go into any hut or hide behind any bush.
[149]
[edit]Autonomy
Another way to define the development of adolescents is their strive for autonomy. According to McElhaney et al., there are three ways in which autonomy can be described. The first being emotional autonomy which is stated as being the development of more adult-like close relationship with adults and peers. The second form of autonomy is behavioral autonomy, which is the ability to be able to make independent decisions and follow through with them. The third is known as cognitive autonomy and is characterized as the manifestation of an independent set of beliefs, values and opinions.
[152] Most of the cultural differences however tend to be visible in behavioral autonomy as this is based on when adolescence are allowed to go on dates, or go out with friends.
One way in which the cultural differences in behavioral autonomy is by comparing the “teen timetables” of parents and adolescents of different cultures. The “teen timetable” is “a questionnaire that asks at what age adolescents should be permitted to engage in various behaviors that signal autonomy.”
[153] When comparing the timetables of White and Asian families across the world, it can be concluded that in general, White parents and adolescents tend to expect autonomy earlier than their Asian counterparts, disregarding whether the families lived in America, Australia, or Hong Kong. It is also the case that an adolescents mental health is best when their feelings of autonomy match closely with their parents.
[154] It is for this reason, recent emigrants, that move from a culture that normally grants autonomy at a later age to a culture with a younger age at which autonomy is granted, often experience family stress. Since adolescence generally become accustomed to the novel culture quicker than adults, the learn to expect autonomy earlier than their parents.
[155]
[edit]Time use
American teenagers spend more time on leisure than many other countries. The average American adolescent spends about five hours a week on homework, while Indian, Taiwanese, and Japanese students spend an average of five hours a day. This is most likely due to the amount of emphasis and pressure that is placed on adolescents’ education in those countries. Americans tend to spend more time playing sports, socializing, caring for their appearance, and working after-school jobs.
[156] Differences in how American teens use their leisure time tend to be influenced by their amount of involvement in various activities rather than ethnicity or socioeconomic background. Busier, more well-rounded teens tend to be better-adjusted and more goal-oriented than their peers who engage in only one activity (such as sports) or none.
[157]
In many developing countries, it is common for adolescents to drop out of high school and start working. These adolescents generally receive full-time positions by the age of 15-16 and they often stay in the same jobs for the remainder of their lifetime.
[158] It is the case though that the rate of adolescents in the workforce today is decreasing. One example of this is China, where as the accessibility of education has increased, the amount of adolescents in the workforce has dropped drastically. Half of all 16-year-olds were employed in 1980 however in 1990, only fewer than one quarter were in workforce.
[159] When comparing more industrialized countries, American adolescents are far more likely to hold jobs than both Asian and European countries. Two thirds of American high school juniors hold jobs during the school year where as only one quarter of Taiwanese and Japanese juniors do.
[156] In many European countries such as France, Hungary and Switzerland adolescents do not work at all and if they do hold jobs, then they are informal, only last for a few hours a week, and more most commonly jobs such as babysitting.
[160]