View source for Social:Adolescence

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'''Adolescence''' ({{etymology|la|adolescere|to grow up}})<ref name="MacmillanDictionaryforStudents">''Macmillan Dictionary for Students'' Macmillan, Pan Ltd. (1981), page 14, 456. Retrieved 2010-7-15.</ref> is a transitional stage of [[Biology:Developmental biology|physical]] and psychological development that generally occurs during the period from puberty to legal adulthood (age of majority).<!--NOTE: THIS DEFINITION WAS THOROUGHLY DISCUSSED on the talk page, spanning two separate discussions. It is reliably sourced and is the consensus version. Most sources state that adolescence begins at puberty and terminates at (legal) adulthood; most cultures define the end of adolescence by the beginning of legal adulthood rather than by biological adulthood or full biological adulthood. Further, at age 18, which is the age of majority in most countries, most people are at full physical development. Thus, any changes to this definition should be discussed on the talk page first.--><ref name=MacmillanDictionaryforStudents/><ref name="Adolescence">{{cite web|title=Adolescence|publisher=''Merriam-Webster''|accessdate=May 9, 2012|url=http://www.merriam-webster.com/dictionary/adolescence}}</ref><ref name="nlm.nih.gov">{{Cite news|title=Puberty and adolescence|publisher=[[Social:MedlinePlus|MedlinePlus]]|accessdate=July 22, 2014|archivedate=April 3, 2013|url=https://www.nlm.nih.gov/medlineplus/ency/article/001950.htm|archiveurl=https://web.archive.org/web/20130403080324/https://www.nlm.nih.gov/medlineplus/ency/article/001950.htm}}</ref> Adolescence is usually associated with the teenage years,<ref name="nlm.nih.gov"/><ref name="psychtoday">{{cite web|title=Adolescence|publisher=''Psychology Today''|accessdate=April 7, 2012|url=http://www.psychologytoday.com/basics/adolescence}}</ref><ref name="lifemodel.org">{{cite web|title=The Theoretical Basis for the Life Model-Research And Resources On Human Development|publisher= |url=http://www.lifemodel.org/download/Model%20Building%20Appendix.pdf|accessdate= 2009-08-11}}</ref><ref name="psychology.sunysb">{{cite web|title=PSY 345 Lecture Notes - Ego Psychologists, Erik Erikson |publisher= |url=http://www.psychology.sunysb.edu/ewaters/345/2007_erikson/2006_erikson.pdf |archiveurl=https://www.webcitation.org/5tWHzkelF?url=http://www.psychology.sunysb.edu/ewaters/345/2007_erikson/2006_erikson.pdf |archivedate=2010-10-16 |accessdate=2009-08-11 |deadurl=yes |df= }}</ref> but its physical, psychological or cultural expressions may begin earlier and end later. For example, puberty now typically begins during preadolescence, particularly in females.<ref name="psychtoday"/><ref name="news.bbc.co.uk">{{cite news|first=Michelle |last=Roberts |title=Why puberty now begins at seven|publisher=BBC News|date=2005-05-15|accessdate=2010-05-22|url=http://news.bbc.co.uk/2/hi/health/4530743.stm}}</ref><ref name="early puberty">{{Cite journal|vauthors=Žukauskaitė S, Lašienė D, Lašas L, Urbonaitė B, Hindmarsh P |title=Onset of breast and pubic hair development in 1231 preadolescent Lithuanian schoolgirls |journal=Arch. Dis. Child. |volume=90 |issue=9 |pages=932–6 |date=September 2005 |pmid=15855182 |pmc=1720558 |doi=10.1136/adc.2004.057612 |url=http://adc.bmj.com/content/90/9/932.full}}</ref><ref name="embryology.med.unsw.edu.au">{{cite web|first=Mark |last=Hill |title=UNSW Embryology Normal Development - Puberty |publisher=embryology.med.unsw.edu.au |accessdate=2008-03-09 |url=http://embryology.med.unsw.edu.au/Child/puberty.htm |archiveurl=https://web.archive.org/web/20080222130620/http://embryology.med.unsw.edu.au/Child/puberty.htm |archivedate=22 February 2008 |deadurl=yes }}</ref><ref>{{cite journal |author1=Dorn L. D. |author2=Biro F. M. | year = 2011| title = Puberty and Its Measurement: A Decade in Review. [Review] | url = | journal = Journal of Research on Adolescence | volume = 21 | issue = 1| pages = 180–195 | doi = 10.1111/j.1532-7795.2010.00722.x }}</ref> Physical growth (particularly in males), and cognitive development can extend into the early twenties. Thus age provides only a rough marker of adolescence, and scholars have found it difficult to agree upon a precise definition of adolescence.<ref name="news.bbc.co.uk"/><ref name="early puberty"/><ref name=falling>{{Cite news|first=Harry|last=Finley|title=Average age at menarche in various cultures|publisher=Museum of Menstruation and Women's Health|url=http://www.mum.org/menarage.htm|work=|pages=|accessdate=2007-08-02|language=| archiveurl= https://web.archive.org/web/20070816115512/http://www.mum.org/menarage.htm| archivedate= 16 August 2007 <!--DASHBot-->| deadurl= no}}</ref><ref name="Delayed puberty">{{cite web|first=Elizabeth|last=Cooney |title=Puberty gap: Obesity splits boys, girls. Adolescent males at top of the BMI chart may be delayed
|publisher=MSNBC|date=2010-02-11|accessdate=2010-05-22|url=http://www.msnbc.msn.com/id/35332881/ns/health-kids_and_parenting/}}</ref>

A thorough understanding of adolescence in society depends on information from various perspectives, including psychology, biology, history, sociology, education, and anthropology. Within all of these perspectives, adolescence is viewed as a transitional period between childhood and adulthood, whose cultural purpose is the preparation of children for adult roles.<ref>Larson, R., & Wilson, S. (2004). Adolescence across place and time: Globalization and the changing pathways to adulthood. In R. Lerner and L. Steinberg Handbook of adolescent psychology. New York: Wiley</ref> It is a period of multiple transitions involving education, training, employment and unemployment, as well as transitions from one living circumstance to another.<ref>Coleman, John; Roker, Debi. Psychologist11. 12 (Dec 1998): 593. "Adolescence".</ref>

The end of adolescence and the beginning of adulthood varies by country. Furthermore, even within a single nation state or culture there can be different ages at which an individual is considered mature enough for society to entrust them with certain privileges and responsibilities. Such privileges and responsibilities include driving a vehicle, having legal sexual relations, serving in the armed forces or on a jury, purchasing and drinking alcohol, voting, entering into contracts, finishing certain levels of education, marriage, and accountability for upholding the law. Adolescence is usually accompanied by an increased independence allowed by the parents or legal guardians, including less supervision as compared to preadolescence.

In studying adolescent development,<ref>{{cite journal | author = Arnett J. J. | year = 2007 | title = Emerging Adulthood: What Is It, and What Is It Good For? | url = | journal = Child Development Perspectives| volume = 1 | issue = 2| pages = 68–73 | doi = 10.1111/j.1750-8606.2007.00016.x }}</ref> adolescence can be defined biologically, as the physical transition marked by the onset of puberty and the termination of physical growth; cognitively, as changes in the ability to think abstractly and multi-dimensionally; or socially, as a period of preparation for adult roles. Major pubertal and biological changes include changes to the [[Biology:Sex organ|sex organ]]s, height, weight, and [[Biology:Muscle|muscle mass]], as well as major changes in brain structure and organization. [[Cognition|Cognitive]] advances encompass both increment in knowledge and in the ability to think abstractly and to reason more effectively. The study of adolescent development often involves interdisciplinary collaborations. For example, researchers in [[Biology:Neuroscience|neuroscience]] or [[Medicine:Behavioral medicine|bio-behavioral health]] might focus on pubertal changes in brain structure and its effects on cognition or social relations. Sociologists interested in adolescence might focus on the acquisition of social roles (e.g., worker or romantic partner) and how this varies across cultures or social conditions.<ref>Côté, J. E. (1996). Identity: A multidimensional analysis. In G. R. Adams, T. Gullotta & R. Montemeyer (Eds.), ''Issues in Adolescent Development (Vol. 6, pp.&nbsp;130–180)''. New York, NY: Sage Publications.</ref> [[Social:Developmental psychology|Developmental psychologists]] might focus on changes in relations with parents and peers as a function of school structure and pubertal status.<ref>Simmons, R., & Blyth, D. (1987). ''Moving into adolescence.'' New York: Aldine de Gruyter.</ref> Some scientists have questioned the universality of adolescence as a developmental phase, arguing that traits often considered typical of adolescents are not in fact inherent to the teenage years.

==Biological development==
===Puberty in general===
[[File:Cubes teenager.jpg|thumb|left|Upper body of a teenage boy. The structure has changed to resemble an [[Biology:Adult|adult]] form.]]
Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The average age of onset of puberty is at 11 for girls and 12 for boys.<ref name=Kail>{{cite book| last = Kail | first = RV |author2=Cavanaugh JC | title = Human Development: A Lifespan View | isbn = 0495600377 | publisher = Cengage Learning | year = 2010|accessdate= September 11, 2014| page = 296 | edition = 5th|url=https://books.google.com/books?id=E-n5E7oyCgoC&pg=PA296#v=onepage&q&f=false}}</ref><ref name="PAmf.org">{{Cite news|title=Teenage Growth & Development: 11 to 14 Years|publisher=Palo Alto Medical Foundation|url=http://www.pamf.org/teen/parents/health/growth-11-14.html|quote=For girls, puberty begins around 10 or 11 years of age and ends around age 16. Boys enter puberty later than girls-usually around 12 years of age-and it lasts until around age 16 or 17.}}</ref> Every person's individual timetable for puberty is influenced primarily by [[Biology:Heredity|heredity]], although environmental factors, such as diet and exercise, also exert some influences.<ref name=Tanner/><ref name=Kaplowitz01>{{Cite journal|doi=10.1542/peds.108.2.347 |vauthors=Kaplowitz PB, Slora EJ, Wasserman RC, Pedlow SE, Herman-Giddens ME |title=Earlier onset of puberty in girls: relation to increased body mass index and race |journal=Pediatrics |volume=108 |issue=2 |pages=347–53 |date=August 2001 |pmid=11483799 |url=http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=11483799}}</ref> These factors can also contribute to [[Medicine:Precocious puberty|precocious]] and [[Medicine:Delayed puberty|delayed puberty]].<ref name="Delayed puberty"/><ref name=Kaplowitz01/>

Some of the most significant parts of pubertal development involve distinctive physiological changes in individuals' height, weight, body composition, and [[Biology:Circulatory system|circulatory]] and respiratory systems.<ref>Marshal, W. (1978). Puberty. In F. Falkner & J.Tanner (Eds.), ''Human growth'', Vol. 2. New York: Plenum.</ref> 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,<ref>{{cite journal |author1=Sisk C. L. |author2=Foster D.L. | year = 2004 | title = The neural basis of puberty and adolescence | url = | journal = Nature Neuroscience | volume = 7 | issue = 10| pages = 1040–1047 | doi = 10.1038/nn1326 | pmid = 15452575 }}</ref> and an active role, referring to changes in hormones during adolescence that trigger behavioral and physical changes.<ref>Coe, C., Hayashi, K., & Levine, S. (1988). Hormones and behavior at puberty: Activation or concatenation. In M. Gunnar & W.A. Collins (Eds.), ''The Minnesota Symposia on Child Psychology'', Vol. 21, pp.&nbsp;17–41. Hillsdale, NJ: Erlbaum.</ref>

Puberty occurs through a long process and begins with a surge in hormone production, which in turn causes a number of physical changes. It is the stage of life characterized by the appearance and development of secondary sex characteristics (for example, a deeper voice and larger [[Medicine:Adam's apple|adam's apple]] in boys, and development of breasts and more curved and prominent hips in girls) and a strong shift in hormonal balance towards an adult state. This is triggered by the [[Medicine:Pituitary gland|pituitary gland]], which secretes a surge of [[Biology:Hormone|hormonal]] agents into the blood stream, initiating a chain reaction to occur. 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 [[Chemistry:Testosterone|testosterone]], and the ovaries predominantly dispense [[Biology:Estrogen|estrogen]]. The production of these hormones increases gradually until sexual maturation is met. Some boys may develop [[Medicine:Gynecomastia|gynecomastia]] due to an imbalance of [[Biology:Sex hormone|sex hormone]]s, tissue responsiveness or obesity.<ref>{{Cite journal|vauthors=Nydick M, Bustos J, Dale JH, Rawson RW |title=Gynecomastia in adolescent boys |journal=JAMA |volume=178 |issue= 5|pages=449–54 |date=November 1961 |pmid=14480779|doi=10.1001/jama.1961.03040440001001 }}</ref>

[[Medicine:Facial hair|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 and 17 years of age.<ref name="pamf.org">{{Cite news|title=Puberty -- Changes for Males|publisher=pamf.org|accessdate=2009-02-20 |url=http://www.pamf.org/teen/health/puberty/physicalchanges.html| archiveurl= https://web.archive.org/web/20090303201905/http://www.pamf.org/teen/health/puberty/physicalchanges.html| archivedate= 3 March 2009 <!--DASHBot-->| deadurl= no}}</ref><ref name="www.ppwr">{{cite web|title=Getting The Facts: Puberty|publisher=ppwr|accessdate=2009-02-20|url=http://www.ppwr.on.ca/03_07.html|archiveurl=https://web.archive.org/web/20090226191204/http://www.ppwr.on.ca/03_07.html|archivedate=26 February 2009|deadurl=yes|df=}}</ref> 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.<ref name="pamf.org"/> 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.<ref name="pamf.org"/> 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.<ref name="www.ppwr"/><ref name="pbskids.org">{{Cite news|title=The No-Hair Scare|publisher=PBS|accessdate=2009-02-20|url=http://pbskids.org/itsmylife/body/puberty/article7.html|archiveurl=https://web.archive.org/web/20090205115944/http://pbskids.org/itsmylife/body/puberty/article7.html|archivedate=5 February 2009|deadurl=yes|df=}}</ref> Some men do not develop full facial hair for 10 years after puberty.<ref name="www.ppwr"/> Facial hair continues to get coarser, darker and thicker for another 2–4 years after puberty.<ref name="www.ppwr"/>

The major landmark of puberty for males is [[Biology:Spermarche|spermarche]], the first [[Medicine:Ejaculation|ejaculation]], which occurs, on average, at age 13.<ref name="Jorgensen & Keiding">(Jorgensen & Keiding 1991).</ref> For females, it is [[Biology:Menarche|menarche]], the onset of menstruation, which occurs, on average, between ages 12 and 13.<ref name="Tanner">(Tanner, 1990).</ref><ref name="U.S. menarche">{{cite journal |vauthors=Anderson SE, Dallal GE, Must A |title=Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart |journal=Pediatrics |volume=111 |issue=4 Pt 1 |pages=844–50 |date=April 2003 |pmid=12671122 |doi=10.1542/peds.111.4.844}}</ref><ref name="Canadian menarche">{{cite journal |title=Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth|publisher=BMC Public Health |year= 2010 |pmid=21110899 |doi=10.1186/1471-2458-10-736 |pmc=3001737 |volume=10 |journal=BMC Public Health |page=736 |vauthors=Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H |issue=1}}</ref><ref name="UK menarche">{{cite journal |url=http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf |title=Obstetrics and Gynaecology |first=Diana |last=Hamilton-Fairley |edition=Second|publisher=Blackwell Publishing }}</ref> The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well.<ref name=Tanner/> Regardless of genes, a girl must have a certain proportion of body fat to attain menarche.<ref name=Tanner/> 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).<ref name=Tanner/><ref name=Kaplowitz01/> Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages.<ref name=Tanner/>

The timing of puberty can have important psychological and social consequences. Early maturing boys are usually taller and stronger than their friends.<ref name=abbassi1998>{{Cite journal|author=Abbassi V |title=Growth and normal puberty |journal=Pediatrics |volume=102 |issue=2 Pt 3 |pages=507–11 |year=1998 |pmid=9685454 |doi=}}</ref> 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.<ref name="Garn">Garn, SM. Physical growth and development. In: Friedman SB, Fisher M, Schonberg SK., editors. Comprehensive Adolescent Health Care. St Louis: Quality Medical Publishing; 1992. Retrieved on 2009-02-20</ref> 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.<ref name=Garn/> 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 [[Cognition|cognitive]] and social development may lag behind their appearance.<ref name=Garn/> Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.<ref name=Susman>Susman, EJ; Dorn, LD; Schiefelbein, VL. Puberty, sexuality, and health. In: Lerner MA, Easterbrooks MA, Mistry J., editors. Comprehensive Handbook of Psychology. New York: Wiley; 2003. Retrieved on 2009-02-20</ref>

For girls, early maturation can sometimes lead to increased self-consciousness, though a typical aspect in maturing females.<ref name="Pamf.org">{{Cite news|title=Teenage Growth & Development: 15 to 17 Years|publisher=Palo Alto Medical Foundation|accessdate=2009-02-20 |url=http://www.pamf.org/teen/parents/health/growth-15-17.html| archiveurl= https://web.archive.org/web/20090226174419/http://www.pamf.org/teen/parents/health/growth-15-17.html| archivedate= 26 February 2009 <!--DASHBot-->| deadurl= no}}</ref> Because of their bodies' developing in advance, pubescent girls can become more insecure and dependent.<ref name="Pamf.org"/> Consequently, girls that reach sexual maturation early are more likely than their peers to develop [[Medicine:Eating disorder|eating disorder]]s (such as [[Medicine:Anorexia nervosa|anorexia nervosa]]). Nearly half of all American high school girls' diets are to lose weight.<ref name="Pamf.org"/> In addition, girls may have to deal with sexual advances from older boys before they are emotionally and mentally mature.<ref>(Peterson, 1987).</ref> 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.<ref>(Caspi et al.1993: Lanza and Collins, 2002)</ref> Those who have had such experiences tend to perform not as well in school as their "inexperienced" peers.<ref>(Stattin & Magnussion, 1990).</ref>

Girls have usually reached full physical development around ages 15–17,<ref name="nlm.nih.gov"/><ref name="PAmf.org"/><ref name="PAMf.org">{{Cite news|title=Teenage Growth & Development: 15 to 17 Years|publisher=Palo Alto Medical Foundation|url=http://www.pamf.org/teen/parents/health/growth-15-17.html}}</ref> while boys usually complete puberty around ages 16–17.<ref name="PAmf.org"/><ref name="PAMf.org"/><ref name="Marshall17677">Marshall (1986), p. 176–7</ref> Any increase in height beyond the post-pubertal age is uncommon. Girls attain reproductive maturity about four years after the first physical changes of puberty appear.<ref name="nlm.nih.gov"/> In contrast, boys accelerate more slowly but continue to grow for about six years after the first visible pubertal changes.<ref name="Garn"/><ref name="Marshall17677"/>

[[File:Child development stages.svg|thumb|center|800px|Approximate outline of development periods in child and teenager development. Adolescence is marked in red at top right.]]

===Growth spurt===
The adolescent growth spurt is a rapid increase in the individual's [[Social:Human height|height]] and weight during puberty resulting from the simultaneous release of growth hormones, thyroid hormones, and androgens.<ref name="Steinberg, L. 2008">Steinberg, L. (2008). ''Adolescence''. New York, NY: McGraw-Hill.</ref> 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&nbsp;inches (10.3&nbsp;cm) a year for males and 3.5&nbsp;inches (9&nbsp;cm) for females.<ref name="Susman, E. 2004">Susman, E., & Rogol, A. (2004). Puberty and psychological development. In R. Lerner & L. Steinberg (Eds.), ''Handbook of adolescent psychology'', New York: Wiley.</ref> 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.<ref name="Susman, E. 2004"/> Teenage and early adult males may continue to gain natural muscle growth even after puberty.<ref name=Garn/>

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.<ref name="Tanner, J. 1972">Tanner, J. (1972). Sequence, tempo, and individual variation in growth and development of boys and girls aged twelve to sixteen. In J. Kagan & R. Coles (Eds.), ''Twelve to sixteen: Early adolescence'', New York: Norton.</ref> This non-uniform growth is one reason why an adolescent body may seem 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 [[Biology:Epiphysis|epiphysis]]. There can be ethnic differences in these skeletal changes. For example, in the United States of America, bone density increases significantly more among black than white adolescents, which might account for decreased likelihood of black women developing [[Medicine:Osteoporosis|osteoporosis]] and having fewer bone fractures there.<ref>{{cite journal |author1=Gilsanz V. |author2=Roe T. |author3=Mora S. |author4=Costin G. |author5=Goodman W. | year = 1991 | title = Changes in vertebral bone density in Black girls and White girls during childhood and puberty | url = | journal = New England Journal of Medicine | volume = 325 | issue = 23| pages = 1597–1600 | doi = 10.1056/NEJM199112053252302 | pmid = 1944449 }}</ref>

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 is 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.<ref>{{cite journal |author1=Smoll F. |author2=Schutz R. | year = 1990 | title = Quantifying gender differences in physical performance: A developmental perspective | url = | journal = Developmental Psychology | volume = 26 | issue = 3| pages = 360–369 | doi = 10.1037/0012-1649.26.3.360 }}</ref>

Pubertal development also affects [[Biology:Circulatory system|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".<ref>Peterson, A., & Taylor, B. (1980). The biological approach to adolescence: Biological change and psychological adaptation. In J. Adelson (Ed.), ''Handbook of adolescent psychology'', pp.129. New York: Wiley.</ref>

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<ref>{{cite journal | author = Goran M. | year = 1998 | title = Developmental changes in energy expenditure and physical activity in children: Evidence for a decline in physical activity in girls before puberty | url = | journal = Pediatrics | volume = 101 | issue = 5| pages = 887–891 | display-authors = 1 | doi = 10.1542/peds.101.5.887 | pmid = 9565420 | last2 = Gower | first2 = BA | last3 = Nagy | first3 = TR | last4 = Johnson | first4 = RK }}</ref><ref>{{cite journal |author1=Savage M. |author2=Scott L. | year = 1998 | title = Physical activity and rural middle school adolescents | url = | journal = Journal of Youth and Adolescence | volume = 27 | issue = 2| pages = 245–253 | doi = 10.1023/A:1021619930697 }}</ref> and may receive inadequate nutrition from diets that often lack important nutrients, such as iron.<ref>{{cite journal |author1=Johnson R. |author2=Johnson D. |author3=Wang M. |author4=Smiciklas-Wright H. |author5=Guthrie H. | year = 1994 | title = Characterizing nutrient intakes of adolescents by sociodemographic factors | url = | journal = Journal of Adolescent Health | volume = 15 | issue = 2| pages = 149–154 | doi = 10.1016/1054-139X(94)90542-8 | pmid = 8018688 }}</ref> These environmental influences in turn affect female physical development.

===Reproduction-related changes===
Primary sex characteristics are those directly related to the [[Biology:Sex organ|sex organ]]s. In males, the first stages of puberty involve growth of the testes and scrotum, followed by growth of the penis.<ref>Goldstein, B. (1976). ''Introduction to human sexuality''. Belmont, CA: Star.</ref> At the time that the penis develops, the seminal vesicles, the [[Biology:Prostate|prostate]], and the bulbourethral gland 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.<ref name="Tanner, J. 1972"/> Boys are generally fertile before they have an adult appearance.<ref name="Steinberg, L. 2008"/>

In females, changes in the primary sex characteristics involve growth of the uterus, vagina, and other aspects of the reproductive system. [[Biology:Menarche|Menarche]], the beginning of menstruation, is a relatively late development which follows a long series of hormonal changes.<ref>{{cite journal | authors = Dorn L.D., Nottelmann E.D., Sussman E.J., Inoff-Germain G., Chrousos G.P. | year = 1999 | title = Variability in hormone concentrations and self-reported menstrual histories in young adolescents: Menarche as an integral part of a developmental process | url = | journal = Journal of Youth and Adolescence | volume = 28 | issue = 3| pages = 283–304 | doi = 10.1023/A:1021680726753 | last5 = Cutler }}</ref> Generally, a girl is not fully fertile until several years after menarche, as regular ovulation follows menarche by about two years.<ref>Hafetz, E. (1976). Parameters of sexual maturity in man. In E. Hafetz (Ed.), ''Perspectives in human reproduction'', Vol. 3: ''Sexual maturity: Physiological and clinical parameters.'' Ann Arbor, MI: Ann Arbor Science Publishers.</ref> 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 breasts, widening of the hips, development of pubic and underarm hair, widening of the areolae, and elevation of the nipples.<ref>Steinberg, L. (2008). ''Adolescence'', 8th ed. New York, NY: McGraw-Hill.</ref> The changes in secondary sex characteristics that take place during puberty are often referred to in terms of five [[Medicine:Tanner scale|Tanner stages]],<ref>{{cite web |url=http://healthvermont.gov/family/toolkit/tools%5CJ-1%20CARD%20Tanner%20Stages.pdf |title=Tanner stages |format=PDF |accessdate=2012-09-15 |deadurl=yes |archiveurl=https://web.archive.org/web/20101205151003/http://healthvermont.gov/family/toolkit/tools/J-1%20CARD%20Tanner%20Stages.pdf |archivedate=2010-12-05 |df= }}</ref> named after the British pediatrician who devised the categorization system.

===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.<ref name="Casey, B. J. 2008">{{cite journal |author1=Casey B. J. |author2=Getz S. |author3=Galvan A. | year = 2008 | title = The adolescent brain | url = | journal = Developmental Review | volume = 28 | issue = 1| pages = 62–77 | doi = 10.1016/j.dr.2007.08.003 | pmid = 18688292 | pmc = 2500212 }}</ref> 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.<ref name="Casey, B. J. 2008"/>

Over the course of adolescence, the amount of [[Biology:White matter|white matter]] in the brain increases linearly, while the amount of [[Biology:Grey matter|grey matter]] in the brain follows an inverted-U pattern.<ref>{{cite journal|last1=Giedd|first1=Jay, N|title=Structural Magnetic Resonance Imaging of the Adolescent Brain|journal=Annals of the New York Academy of Sciences|date=2004|volume=1021|issue=1|pages=77–85|doi=10.1196/annals.1308.009}}</ref> Through a process called [[Biology:Synaptic pruning|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 [[Biology:Myelin|myelin]]ation (insulation of axons) and the reduction of unused pathways.<ref>{{cite journal |author1=Giedd J. N. |author2=Blumenthal J. |author3=Jeffries N. O. |author4=Castellanos F. X. |author5=Liu H. |author6=Zijdenbos A. |author7=Rapoport J. L. | year = 1999 | title = Brain development during childhood and adolescence: a longitudinal MRI study | url = | journal = Nature Neuroscience | volume = 2 | issue = 10| pages = 861–863 | doi = 10.1038/13158 | pmid = 10491603 }}</ref>

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 [[Biology:Prefrontal cortex|prefrontal]] cortices, among other regions.<ref>{{cite journal |author1=Gogtay N. |author2=Giedd J. N. |author3=Lusk L. |author4=Hayashi K. M. |author5=Greenstein D. |author6=Vaituzis A. C. |author7=Thompson P. M. | year = 2004 | title = Dynamic mapping of human cortical development during childhood through early adulthood | url = | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 101 | issue = 21| pages = 8174–8179 | doi = 10.1073/pnas.0402680101 | pmid = 15148381 | pmc = 419576 }}</ref> 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.<ref>{{cite journal |author1=Segalowitz S. J. |author2=Davies P. L. | year = 2004 | title = Charting the maturation of the frontal lobe: An electrophysiological strategy | url = | journal = Brain and Cognition | volume = 55 | issue = 1| pages = 116–133 | doi = 10.1016/S0278-2626(03)00283-5 | pmid = 15134847 }}</ref> 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.

Three [[Biology:Neurotransmitter|neurotransmitter]]s that play important roles in adolescent brain development are [[Chemistry:Glutamic acid|glutamate]], [[Biology:Dopamine|dopamine]] and [[Chemistry:Serotonin|serotonin]]. 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.<ref>Weinberger, D.R., Elvevåg, B., Giedd, J.N. (2005). The Adolescent Brain: A Work in Progress. ''The National Campaign to Prevent Teen Pregnancy''.</ref> Because of this, by early adulthood the synaptic balance in the brain is more inhibitory than excitatory.

[[Biology:Dopamine|Dopamine]] is associated with pleasure and attuning to the environment during decision-making. During adolescence, dopamine levels in the [[Philosophy:Limbic system|limbic system]] increase and input of dopamine to the prefrontal cortex increases.<ref>{{cite journal | author = Spear L. P. | year = 2000 | title = The adolescent brain and age-related behavioral manifestations | url = http://faculty.weber.edu/eamsel/Classes/Child%203000/Adolescent%20Risk%20taking/Lectures/3-4%20Biological/Spear%20LV%20%20(2000).pdf| journal = Neuroscience and Biobehavioral Reviews | volume = 24 | issue = 4| pages = 417–463 | doi = 10.1016/S0149-7634(00)00014-2 | pmid = 10817843 }}</ref> 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).

[[Chemistry:Serotonin|Serotonin]] is a neuromodulator involved in regulation of mood and behavior. 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 [[Chemistry:Serotonin|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. The effect of serotonin is not limited to the limbic system: Several serotonin receptors have their gene expression change dramatically during adolescence, particularly in the human frontal and prefrontal cortex 
.<ref name="pmid24721318">{{cite journal | doi = 10.1016/j.euroneuro.2014.02.009 | authors = Shoval, G., Bar-Shira O., Zalsman G., John J. Mann and Chechik G. (2014) Transitions in the transcriptome of the serotonergic and dopaminergic systems in the human brain during adolescence. European Neuropsychopharmacology. | pmid = 24721318 | year = 2014 | title = Transitions in the transcriptome of the serotonergic and dopaminergic systems in the human brain during adolescence | journal = European Neuropsychopharmacology | volume=24 | issue=7 | pages=1123–32}}</ref>

==Cognitive development==
Adolescence is also a time for rapid cognitive development.<ref>{{cite book|url=https://books.google.com/?id=s916RMYHgJIC&pg=PA237&lpg=PA237&dq=adolescents+rapid+%22cognitive+development%22#v=onepage&q=adolescents%20rapid%20%22cognitive%20development%22&f=false |title=S.R. Smith & L. Handler: '&#39;The clinical assessment of children and adolescents: a practitioner's handbook.'&#39; (2007) |publisher=Books.google.com |accessdate=2012-09-15|isbn=9780805860757 |year=2007 }}</ref> [[Biography:Jean Piaget|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.<ref>{{cite web|url=http://etr.org/recapp/theories/AdolescentDevelopment/developmentalTheories.htm|archiveurl=https://web.archive.org/web/20090227022804/http://etr.org/recapp/theories/AdolescentDevelopment/developmentalTheories.htm|archivedate=2009-02-27 |title=ReCAPP: Theories & Approaches: Adolescent Development |publisher=Etr.org |accessdate=2013-08-16}}</ref> A combination of behavioural and [[Physics:Functional magnetic resonance imaging|fMRI]] studies have demonstrated development of [[Philosophy:Executive functions|executive functions]], that is, cognitive skills that enable the control and coordination of thoughts and behaviour, which are generally associated with the [[Biology:Prefrontal cortex|prefrontal cortex]].<ref>{{cite journal | last1 = Choudhury | first1 = S. | last2 = Blakemore | first2 = S.-J. | last3 = Charman | first3 = T. | title = Social cognitive development during adolescence | journal = Social Cognitive and Affective Neuroscience | volume = 1 | pages = 165–74 | year = 2006 | doi = 10.1093/scan/nsl024 | issue = 3 | pmid = 18985103 | pmc = 2555426 }}</ref> 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.<ref>{{Cite journal|author=Pedersen S |title=Personality formation in adolescence and its impact upon the psycho-analytical treatment of adults |journal=Int J Psychoanal |volume=42 |issue= |pages=381–8 |year=1961 |pmid=14484851 }}</ref>

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 varies between individuals, but the changes discussed below begin at puberty or shortly after that and some skills continue to develop as the adolescent ages. The [[Philosophy:Dual systems model|dual systems model]] proposes a maturational imbalance between development of the socioemotional system and cognitive control systems in the brain that contribute to impulsivity and other behaviors characteristic of adolescence.<ref>{{Cite journal|last=Steinberg|first=Laurence|date=2010-04-01|title=A dual systems model of adolescent risk-taking|url=http://onlinelibrary.wiley.com/doi/10.1002/dev.20445/abstract|journal=Developmental Psychobiology|language=en|volume=52|issue=3|pages=216–224|doi=10.1002/dev.20445|issn=1098-2302}}</ref>

===Theoretical perspectives===
There are at least two major approaches to understanding cognitive change during adolescence. One is the constructivist view of cognitive development. Based on the work of [[Biography:Jean Piaget|Piaget]], it takes a quantitative, state-theory approach, hypothesizing that adolescents' cognitive improvement is relatively sudden and drastic. The second is the [[Information processing|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.

===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 [[Philosophy:Attention#Selective attention|selective attention]], the process by which one focuses on one stimulus while tuning out another. [[Philosophy:Attention|Divided attention]], the ability to pay attention to two or more stimuli at the same time, also improves.<ref>{{cite journal |author1=Higgins A. |author2=Turnure J. | year = 1984 | title = Distractibility and concentration of attention in children's development | url = | journal = Child Development | volume = 55 | issue = 5| pages = 1799–1810 | doi=10.1111/j.1467-8624.1984.tb00422.x }}</ref><ref>{{cite journal |author1=Schiff A. |author2=Knopf I. | year = 1985 | title = The effects of task demands on attention allocation in children of different ages | url = | journal = Child Development | volume = 56 | issue = 3| pages = 621–630 | doi = 10.2307/1129752 }}</ref>
# Memory. Improvements are seen in both [[Working memory|working memory]] and [[Biology:Long-term memory|long-term memory]].<ref>Keating, D. (2004). Cognitive and brain development. In R. Lerner & L. Steinberg (Eds.), ''Handbook of Adolescent Psychology'' (2nd ed.). New York: Wiley.</ref>
# 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.<ref>{{cite journal |author1=Kali R.V. |author2=Ferrer E. | year = 2007 | title = Processing speed in childhood and adolescence: Longitudinal models for examining developmental change | url = | journal = Child Development | volume = 78 | issue = 6| pages = 1760–1770 | doi = 10.1111/j.1467-8624.2007.01088.x | pmid = 17988319 }}</ref>
# Organization. Adolescents are more aware of their thought processes and can use mnemonic devices and other strategies to think more efficiently.<ref>Brown, A. (1975). The development of memory: Knowing, knowing about knowing, and knowing how to know. In H. Reese (Ed.), ''Advances in child development and behavior'' (Vol. 10). New York: Academic Press.</ref>
# [[Philosophy:Metacognition|Metacognition]].

Studies since 2005 indicate that the brain is not fully formed until the early twenties.<ref>{{cite web|url=http://www.health.harvard.edu/blog-extra/the-adolescent-brain-beyond-raging-hormones|title=The adolescent brain: Beyond raging hormones - Harvard Health|first=Harvard Health|last=Publishing|publisher=}}</ref>

===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|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 [[Philosophy:Sarcasm|sarcasm]]. (Children younger than age nine often cannot comprehend sarcasm at all.)<ref>{{cite journal |author1=Demorest A. |author2=Meyer C. |author3=Phelps E. |author4=Gardner H. |author5=Winner E. | year = 1984 | title = Words speak louder than actions: Understanding deliberately false remarks | url = | journal = Child Development | volume = 55 | issue = 4| pages = 1527–1534 | doi=10.2307/1130022 |jstor=1130022 }}</ref> 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, fairness, and honesty.

===Metacognition===
A third gain in cognitive ability involves thinking about thinking itself, a process referred to as [[Philosophy:Metacognition|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 [[Philosophy:Introspection|introspection]], [[Philosophy:Self-consciousness|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.<ref>{{cite journal |author1=Rankin J.L. |author2=Lane D.J. |author3=Gibbons F.X. |author4=Gerrard M. | year = 2004 | title = Adolescent self-consciousness: longitudinal age changes and gender differences in two cohorts | url = | journal = Journal of Research on Adolescence | volume = 14 | issue = | pages = 1–21 | doi = 10.1111/j.1532-7795.2004.01401001.x }}</ref>

Related to metacognition and [[Philosophy:Abstraction|abstract thought]], perspective-taking involves a more sophisticated [[Philosophy:Theory of mind|theory of mind]].<ref>Smetana, J., & Villalobos, M. (2009). Social cognitive development in adolescence. In R. Lerner & L. Steinber (Eds.), ''Handbook of adolescent psychology'' (3rd ed., Vol. 1, pp.&nbsp;187–228. New York: Wiley.</ref> 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.<ref>Selman, R. (1980) ''The growth of interpersonal understanding: Developmental and clinical analyses''. New York: Academic Press.</ref>

===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.<ref>{{cite journal | author = Chandler M | year = 1987 | title = The Othello effect: Essay on the emergence and eclipse of skeptical doubt | url = | journal = Human Development | volume = 30 | issue = 3| pages = 137–159 | doi=10.1159/000273174}}</ref>

===Wisdom===
[[Philosophy:Wisdom|Wisdom]], or the capacity for insight and judgment that is developed through experience,<ref>{{cite journal|author1=Pasupathi M. |author2=Staudinger U.M. |author3=Bates P.B. | year = 2001| title = Seeds of wisdom: Adolescents' knowledge and judgment about difficult life problems|url =|journal = Developmental Psychology|volume = 37|issue = 3|pages = 351–361|doi = 10.1037/0012-1649.37.3.351|pmid = 11370911}}</ref> 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 [[Philosophy:Intelligence quotient|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 in this way.

===Risk-taking===

Because most injuries sustained by adolescents are related to risky behavior (car crashes, alcohol, unprotected sex), a great deal of research has been done on the cognitive and emotional processes underlying adolescent risk-taking.  In addressing this question, it is important to distinguish whether adolescents are more likely to engage in risky behaviors (prevalence), whether they make risk-related decisions similarly or differently than adults (cognitive processing perspective), or whether they use the same processes but value different things and thus arrive at different conclusions.  The behavioral decision-making theory proposes 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.<ref>{{cite journal|author1=Albert D. |author2=Steinberg L. |year = 2011|title = Judgment and Decision Making in Adolescence| url =|journal = Journal of Research on Adolescence| volume = 21 | issue = 1| pages = 211–224 | doi = 10.1111/j.1532-7795.2010.00724.x }}</ref>

Research seems to favor the hypothesis that adolescents and adults think about risk in similar ways, but hold different values and thus come to different conclusions.  Some have argued that there may be evolutionary benefits to an increased propensity for risk-taking in adolescence.  For example, without a willingness to take risks, teenagers would not have the motivation or confidence necessary to leave their family of origin.  In addition, from a population perspective, there is an advantage to having a group of individuals willing to take more risks and try new methods, counterbalancing the more conservative elements more typical of the received knowledge held by older adults.  Risktaking 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 [[Social:Sensation seeking|sensation seeking]] may affect risk-taking behavior throughout the lifespan.<ref>{{cite journal |author1=Johnson C.A. |author2=Xiao L. |author3=Palmer P. |author4=Sun P. |author5=Want Q. |author6=Wei Y. | year = 2008 | title = Affective decision-making deficits, linked to a dysfunctional ventromedial prefrontal cortex, revealed in 10th grade Chinese adolescent binge drinkers | journal = Neuropsychologia | volume = 46 | issue = 2| pages = 714–726 | doi=10.1016/j.neuropsychologia.2007.09.012|display-authors=0 | pmid=17996909 | pmc=3498846}}</ref><ref>{{cite journal |author1=Miller D. |author2=Byrnes J. | year = 1997 | title = The role of contextual and personal factors in children's risk taking | url = | journal = Developmental Psychology | volume = 33 | issue = 5| pages = 814–823 | doi = 10.1037/0012-1649.33.5.814 | pmid = 9300214 }}</ref>

Given the potential consequences, engaging in sexual behavior is somewhat risky, particularly for adolescents. Having unprotected sex, using poor birth control methods (e.g. withdrawal), having multiple sexual partners, and poor communication are some aspects of sexual behavior that increase individual and/or social risk. Some qualities of adolescents' lives that are often correlated with [[Medicine:Risky sexual behavior|risky sexual behavior]] include higher rates of experienced abuse, lower rates of parental support and monitoring.<ref>{{cite journal |author1=Luster Tom |author2=Small Stephen A | year = 1994 | title = Factors Associated with Sexual Risk-Taking Behaviors Among Adolescents | doi = 10.2307/352873 | journal = Journal of Marriage and Family | volume = 46 | issue = 3| pages = 622–632 |jstor=352873 }}</ref>

=== Inhibition ===
Related to their increased tendency for risk-taking, adolescents show impaired behavioral inhibition, including deficits in [[Philosophy:Extinction (psychology)|extinction learning]].<ref>{{Cite journal|last=McCallum|first=Jessica|last2=Kim|first2=Jee Hyun|last3=Richardson|first3=Rick|date=2010-09-01|title=Impaired Extinction Retention in Adolescent Rats: Effects of D-Cycloserine|journal=Neuropsychopharmacology|volume=35|issue=10|pages=2134–2142|doi=10.1038/npp.2010.92|issn=0893-133X|pmc=3055297|pmid=20592716}}</ref> This has important implications for engaging in risky behavior such as unsafe sex or illicit drug use, as adolescents are less likely to inhibit actions that may have negative outcomes in the future.<ref>{{Cite journal|last=Spear|first=Linda Patia|date=2013-02-01|title=Adolescent Neurodevelopment|journal=The Journal of Adolescent Health|volume=52|issue=2 0 2|pages=S7–13|doi=10.1016/j.jadohealth.2012.05.006|issn=1054-139X|pmc=3982854|pmid=23332574}}</ref> This phenomenon also has consequences for behavioral treatments based on the principle of extinction, such as cue exposure therapy for anxiety or drug addiction.<ref>{{Cite journal|last=Kim|first=Jee Hyun|last2=Richardson|first2=Rick|date=2010-02-15|title=New findings on extinction of conditioned fear early in development: theoretical and clinical implications|journal=Biological Psychiatry|volume=67|issue=4|pages=297–303|doi=10.1016/j.biopsych.2009.09.003|issn=1873-2402|pmid=19846065}}</ref><ref>{{Cite journal|last=Kim|first=Jee Hyun|last2=Ganella|first2=Despina E|date=2015-02-01|title=A Review of Preclinical Studies to Understand Fear During Adolescence|url=http://onlinelibrary.wiley.com/doi/10.1111/ap.12066/abstract|journal=Australian Psychologist|language=en|volume=50|issue=1|pages=25–31|doi=10.1111/ap.12066|issn=1742-9544}}</ref> It has been suggested that impaired inhibition, specifically extinction, may help to explain adolescent propensity to relapse to drug-seeking even following behavioral treatment for addiction.<ref>{{Cite journal|last=Zbukvic|first=Isabel C.|last2=Ganella|first2=Despina E.|last3=Perry|first3=Christina J.|last4=Madsen|first4=Heather B.|last5=Bye|first5=Christopher R.|last6=Lawrence|first6=Andrew J.|last7=Kim|first7=Jee Hyun|date=2016-03-05|title=Role of Dopamine 2 Receptor in Impaired Drug-Cue Extinction in Adolescent Rats|url=http://cercor.oxfordjournals.org/content/early/2016/03/05/cercor.bhw051|journal=Cerebral Cortex|language=en|pages=2895–904|doi=10.1093/cercor/bhw051|issn=1047-3211|pmid=26946126|pmc=4869820|volume=26|issue=6}}</ref>

==Psychological development==
[[File:G. Stanley Hall.jpg|thumb|G. Stanley Hall]]
The formal study of adolescent psychology began with the publication of [[Biography:G. Stanley Hall|G. Stanley Hall]]'s "Adolescence in 1904". Hall, who was the first president of the [[Organization:American Psychological Association|American Psychological Association]], viewed adolescence primarily as a time of internal turmoil and upheaval (''sturm und drang''). This understanding of [[Social:Youth|youth]] was based on two then new ways of understanding human behavior: [[Biology:Darwinism|Darwin's evolutionary theory]] and Freud's psychodynamic theory.  He believed that adolescence was a representation of our human ancestors' phylogenetic shift from being primitive to being civilized. Hall's assertions stood relatively uncontested until the 1950s when psychologists such as [[Biography:Erik Erikson|Erik Erikson]] and Anna Freud started to formulate their theories about adolescence. Freud believed that the psychological disturbances associated with youth were biologically based and culturally universal while Erikson focused on the dichotomy between [[Philosophy:Identity formation|identity formation]] and role fulfillment.<ref name="Lerner, R.M, & Steinberg, L.D. 2004">{{cite book|title=Handbook of Adolescent Psychology|year=2004|publisher={{wipe|John Wiley & Sons}}|location=Hoboken, NJ|author=Lerner, R.M |author2=Steinberg, L.D. |last-author-amp=yes|edition=2}}</ref> Even with their different theories, these three psychologists agreed that adolescence was inherently a time of disturbance and psychological confusion. The less turbulent aspects of adolescence, such as peer relations and cultural influence, were left largely ignored until the 1980s. From the '50s until the '80s, the focus of the field was mainly on describing patterns of behavior as opposed to explaining them.<ref name="Lerner, R.M, & Steinberg, L.D. 2004"/>

Jean Macfarlane founded the [[Organization:University of California, Berkeley|University of California, Berkeley]]'s Institute of Human Development, formerly called the Institute of Child Welfare, in 1927.<ref name=NYT19890318>{{cite news|url=https://www.nytimes.com/1989/03/18/obituaries/jean-macfarlane-95-psychology-professor.html |title=Jean Macfarlane, 95, Psychology Professor - New York Times |publisher=Nytimes.com |date=1989-03-18 |accessdate=2013-08-16}}</ref><!--will clean up reference--> The Institute was instrumental in initiating studies of healthy development, in contrast to previous work that had been dominated by theories based on pathological personalities.<ref name=NYT19890318 /> The studies looked at human development during the [[Finance:Great Depression|Great Depression]] and [[Social:World War II|World War II]], unique historical circumstances under which a generation of children grew up. The Oakland Growth Study, initiated by Harold Jones and Herbert Stolz in 1931, aimed to study the physical, intellectual, and social development of children in the Oakland area. Data collection began in 1932 and continued until 1981, allowing the researchers to gather longitudinal data on the individuals that extended past adolescence into adulthood. Jean Macfarlane launched the Berkeley Guidance Study, which examined the development of children in terms of their socioeconomic and family backgrounds.<ref>{{cite web|title=The Oakland Growth and Berkeley Guidance Studies of the Institute of Human Development at the University of California, Berkeley|url=http://www.cpc.unc.edu/projects/lifecourse/research_projects/oakland_berkeley|archiveurl=https://web.archive.org/web/20120912072515/http://www.cpc.unc.edu/projects/lifecourse/research_projects/oakland_berkeley|archivedate=2012-09-12|publisher=University of North Carolina|accessdate=4 October 2012}}</ref> These studies provided the background for Glen Elder in the 1960s, to propose a life-course perspective of adolescent development. Elder formulated several descriptive principles of adolescent development. The principle of historical time and place states that an individual's development is shaped by the period and location in which they grow up. The principle of the importance of timing in one's life refers to the different impact that life events have on development based on when in one's life they occur. The idea of linked lives states that one's development is shaped by the interconnected network of relationships of which one is a part; and the principle of human agency asserts that one's life course is constructed via the choices and actions of an individual within the context of their historical period and social network.<ref>{{cite journal|last=Elder|first=Glen|title=The life course as developmental theory|journal=Child Development|date=February 1998|volume=69|issue=1|pages=1–12|doi=10.1111/j.1467-8624.1998.tb06128.x|pmid=9499552}}</ref>

In 1984, the Society for Research on Adolescence (SRA) became the first official organization dedicated to the study of adolescent psychology. Some of the issues first addressed by this group include: the [[Philosophy:Nature versus nurture|nature versus nurture]] debate as it pertains to adolescence; understanding the interactions between adolescents and their environment; and considering culture, social groups, and historical context when interpreting adolescent behavior.<ref name="Lerner, R.M, & Steinberg, L.D. 2004"/>

Evolutionary biologists like Jeremy Griffith have drawn parallels between adolescent psychology and the developmental evolution of modern humans from hominid ancestors as a manifestation of [[Biology:Recapitulation theory|ontogeny recapitulating phylogeny]].<ref>{{cite book|last=Griffith|first=Jeremy|title=Freedom|year=2011|isbn=978-1-74129-011-0|url=http://www.worldtransformation.com/freedom-book1-sobered-and-depressed-adolescentman/}}</ref>

==Social development==

===Identity development===

Identity development is a stage in the adolescent life cycle.<ref name="Kroger, J. 1996 pp. 40-46">Kroger, J. (1996) The Balance Between Self and Other. (pp. 40-46). New York, U.S.A. [[Company:Routledge|Routledge]]</ref> For most, the search for identity begins in the adolescent years. During these years, adolescents are more open to 'trying on' different behaviours and appearances to discover who they are.<ref name="Strasburger, V.C. 2014 pp. 11-19">Strasburger, V.C., Wilson B.J., Jordan, A.B. (2014) Children and Adolescents: Unique Audiences. Children, Adolescents, and the Media. (pp. 11-19). U.S.A: SAGE Publications</ref> In an attempt to find their identity and discover who they are, adolescents are likely to cycle through a number of identities to find one that suits them best. Developing and maintaining identity (in adolescent years) is a difficult task due to multiple factors such as family life, environment, and social status.<ref name="Kroger, J. 1996 pp. 40-46"/> Empirical studies suggest that this process might be more accurately described as [[Philosophy:Identity formation|identity development]], rather than formation, but confirms a normative process of change in both content and structure of one's thoughts about the self.<ref>Steinberg, L. (2008). ''Adolescence'', 8th ed. New York, NY: McGraw-Hill.</ref> The two main aspects of identity development are self-clarity and self-esteem.<ref name="Strasburger, V.C. 2014 pp. 11-19"/> Since choices made during adolescent years can influence later life, high levels of self-awareness and self-control during mid-adolescence will lead to better decisions during the transition to adulthood.{{Citation needed|date=September 2013}} Researchers have used three general approaches to understanding identity development: self-concept, sense of identity, and self-esteem. The years of adolescence create a more conscientious group of young adults. Adolescents pay close attention and give more time and effort to their appearance as their body goes through changes. Unlike children, teens put forth an effort to look presentable (1991).<ref name="psychtoday"/> The environment in which an adolescent grows up also plays an important role in their identity development. Studies done by the [[Organization:American Psychological Association|American Psychological Association]] have shown that adolescents with a less privileged upbringing have a more difficult time developing their identity.<ref name="APA on adolescent environment">[[Organization:American Psychological Association|American Psychological Association]] (APA). United States Department of Health and Human Services.</ref>

====Self-concept====
The idea of self-concept is known as the ability of a person to have opinions and beliefs that are defined confidently, consistent and stable.<ref name="sciencedirect.com">{{cite journal | doi = 10.1016/j.jadohealth.2010.08.020 | volume=48 | issue=2 | title=Online Communication Among Adolescents: An Integrated Model of Its Attraction, Opportunities, and Risks | journal=Journal of Adolescent Health | pages=121–127 | pmid=21257109 | date=February 2011 |vauthors=Valkenburg PM, Peter J }}</ref> Early in adolescence, [[Philosophy:Cognitive development|cognitive development]]s 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 by physical traits whereas adolescents define themselves based on their values, thoughts, and opinions.<ref>{{cite book|last=Carlson|first=Neil R.|title=Psychology: the science of behaviour|year=2010|publisher=Pearson Education Canada|location=Toronto, Ontario}}</ref>

Adolescents can conceptualize multiple "possible selves" that they could become<ref name="Markus1986">{{cite journal|author1=Markus H. |author2=Nurius P. |year = 1986 | title = Possible selves|url =|journal = American Psychologist|volume = 41|issue = 9| pages = 954–969 | doi = 10.1037/0003-066X.41.9.954 }}</ref> and long-term possibilities and consequences of their choices.<ref>Nurmi, J. (2004). Socialization and self-development: Channeling, selection, adjustment, and reflection. In R. Lerner & L. Steinberg (Eds.), ''Handbook of adolescent psychology''. New York: Wiley.</ref> Exploring these possibilities may result in abrupt changes in self-presentation as the adolescent chooses or rejects qualities and behaviors, trying to guide the [[Philosophy:Self-discrepancy theory#Actual|actual]] self toward the [[Philosophy:Self-discrepancy theory#Ideal|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.<ref name="Markus1986" /><ref>{{cite journal |author1=Oyserman D. |author2=Markus H. | year = 1990 | title = Possible selves and deliquency. | url = | journal = Journal of Personality and Social Psychology | volume = 59 | issue = 1| pages = 112–125 | doi = 10.1037/0022-3514.59.1.112 | pmid = 2213484 }}</ref>

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.<ref name="Harter, S. 1999">Harter, S. (1999). ''The construction of the self''. New York: Guilford Press.</ref> Differentiation appears fully developed by mid-adolescence.<ref>{{cite journal | author = Marsh H | year = 1989 | title = Age and sex differences in multiple dimensions of self-concept: Preadolescence to earl adulthood | url = | journal = Journal of Educational Psychology | volume = 81 | issue = 3| pages = 417–430 | doi=10.1037/0022-0663.81.3.417}}</ref> 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 [[Philosophy:Cognitive dissonance|Cognitive dissonance]]),<ref>{{cite journal |author1=Harter S. |author2=Monsour A. | year = 1992 | title = Developmental analysis of conflict caused by opposing attributes in the adolescent self-portrait | url = | journal = Developmental Psychology | volume = 28 | issue = 2| pages = 251–260 | doi = 10.1037/0012-1649.28.2.251 }}</ref> but this distress may benefit adolescents by encouraging structural development.

====Sense of identity====
[[Philosophy:Egocentrism|Egocentrism]] in adolescents forms a self-conscious desire to feel important in their peer groups and enjoy social acceptance.<ref>Carlson, N. R., & Heth, C. (2010).</ref> 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 [[Biography:Erik Erikson|Erik Erikson]] argued that not everyone fully achieves identity. Erikson's theory of [[Social:Erikson's stages of psychosocial development|stages of development]] includes the [[Social:Identity crisis|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" but also stressed that the identity challenge "is never fully resolved once and for all at one point in time".<ref>Steinberg, L. (2008). ''Adolescence'', 8th ed. 287. New York, NY: McGraw-Hill.</ref> Adolescents begin by defining themselves based on their crowd membership. "Clothes help teens explore new identities, separate from parents, and bond with peers." Fashion has played a major role when it comes to teenagers "finding their selves"; Fashion is always evolving, which corresponds with the evolution of change in the personality of teenagers.<ref>"You're Wearing That?" by Stacey Schultz. U.S. News & World Report Special Issue</ref> Adolescents attempt to define their identity by consciously styling themselves in different manners to find what best suits them. Trial and error in matching both their perceived image and the image others respond to and see, allows for the adolescent to grasp an understanding of who they are.<ref name="Rawlins">{{Citation |last=Rawlins |first=W.K. |title= Friendship matters: Communication, dialectics, and life course |publisher= Aldine de Gruyter |place= New York |year= 1992}}</ref>

Just as fashion is evolving to influence adolescents so is the media. "Modern life takes place amidst a never-ending barrage of flesh on screens, pages, and billboards."<ref>"The Media Assault on Male Body Image" by Brandon Klein. Seed Magazine.</ref> This barrage consciously or subconsciously registers into the mind causing issues with self-image a factor that contributes to an adolescence sense of identity. Researcher James Marcia developed the current method for testing an individual's progress along these stages.<ref>{{cite journal | author = Marcia J | year = 1966 | title = Development and validation of ego identity status | url = | journal = Journal of Personality and Social Psychology | volume = 3 | issue = 5| pages = 551–558 | doi = 10.1037/h0023281 | pmid = 5939604 }}</ref><ref>{{cite journal | author = Marcia J | year = 1976 | title = Identity six years after: A follow-up study | url = | journal = Journal of Personality and Social Psychology | volume = 3 | issue = 5| pages = 551–558 | pmid = 5939604 | doi=10.1037/h0023281}}</ref> His questions are divided into three categories: occupation, ideology, and [[Social:Interpersonal relationship|interpersonal relationship]]s. 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.<ref name="ReferenceA">Steinberg, L. (2008). ''Adolescence'', 8th ed. 286. New York, NY: McGraw-Hill.</ref>

Research since reveals self-examination beginning early in adolescence, but identity achievement rarely occurring before age 18.<ref>Marcia, J. (1980). Identity in adolescence. In J. Adelson (Ed.), ''Handbook of adolescent psychology'', pp.&nbsp;159–187. New York: Wiley.</ref> 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.<ref>Montemayor, R., Brown, B., & Adams, G. (1985). Changes in identity status and psychological adjustment after leaving home and entering college. Paper presented at the biennial meetings of the Society for Research in Child Development, Toronto.</ref> For the most part, evidence has supported Erikson's stages: each correlates with the personality traits he originally predicted.<ref name="ReferenceA"/> Studies also confirm the impermanence of the stages; there is no final endpoint in identity development.<ref>Steinberg, L. (2008). ''Adolescence'', 8th ed. 288. New York, NY: McGraw-Hill.</ref>

====Environment and identity====
An adolescent's environment plays a huge role in their identity development.<ref name="APA on adolescent environment"/> While most adolescent studies are conducted on white, middle class children, studies show that the more privileged upbringing people have, the more successfully they develop their identity.<ref name="APA on adolescent environment"/> The forming of an adolescent's identity is a crucial time in their life. It has been recently found that demographic patterns suggest that the transition to adulthood is now occurring over a longer span of years than was the case during the middle of the 20th century. Accordingly, youth, a period that spans late adolescence and early adulthood, has become a more prominent stage of the life course. This therefore has caused various factors to become important during this development.<ref>{{cite journal|last=Furstenberg|first=Frank F.|title=The Sociology of Adolescence and Youth in the 1990s: A Critical Commentary|journal=Journal of Marriage and Family|date=November 2000|volume=62|issue=4|pages=896–910|doi=10.1111/j.1741-3737.2000.00896.x}}</ref>  So many factors contribute to the developing social identity of an adolescent from commitment, to coping devices,<ref>How do Young Adolescents Cope With Social Problems? An Examination of Social Goals, Coping With Friends, and Social Adjustment. ''Journal of Early Adolescence.''</ref> to social media. All of these factors are affected by the environment an adolescent grows up in. A child from a more privileged upbringing is exposed to more opportunities and better situations in general. An adolescent from an inner city or a crime-driven neighborhood is more likely to be exposed to an environment that can be detrimental to their development.  Adolescence is a sensitive period in the development process, and exposure to the wrong things at that time can have a major effect on future decisions.  While children that grow up in nice suburban communities are not exposed to bad environments they are more likely to participate in activities that can benefit their identity and contribute to a more successful identity development.<ref name="APA on adolescent environment"/>

====Sexual orientation and identity====
[[Social:Sexual orientation|Sexual orientation]] has been defined as "an erotic inclination toward people of one or more genders, most often described as sexual or erotic attractions".<ref name="Saewyc">{{cite journal|last=Saewyc|first=E.M.|title=Research on Adolescent Sexual Orientation: Development, Health Disparities, Stigma, and Resilience|journal=Journal of Research on Adolescence|year=2011|volume=21|issue=1|pages=256–272|doi=10.1111/j.1532-7795.2010.00727.x|pmid=27099454|pmc=4835230}}</ref> In recent years, psychologists have sought to understand how sexual orientation develops during adolescence. Some theorists believe that there are many different possible developmental paths one could take, and that the specific path an individual follows may be determined by their sex, orientation, and when they reached the onset of puberty.<ref name="Saewyc"/>

In 1989, Troiden proposed a four-stage model for the development of homosexual sexual identity.<ref>{{cite journal|last=Troiden|first=R. R.|title=The formation of homosexual identities|journal=Journal of Homosexuality|year=1989|volume=17|pages=43–73|doi=10.1300/J082v17n01_02|pmid=2668403|issue=1–2}}</ref>  The first stage, known as sensitization, usually starts in childhood, and is marked by the child's becoming aware of same-sex attractions. The second stage, identity confusion, tends to occur a few years later. In this stage, the youth is overwhelmed by feelings of inner turmoil regarding their sexual orientation, and begins to engage sexual experiences with same-sex partners. In the third stage of identity assumption, which usually takes place a few years after the adolescent has left home, adolescents begin to come out to their family and close friends, and assumes a self-definition as gay, lesbian, or bisexual.<ref>{{cite journal|last=Floyd|first=Frank J.|author2=Stein, Terry S.|title=Sexual orientation identity formation among gay, lesbian, and bisexual youths: Multiple patterns of milestone experiences|journal=Journal of Research on Adolescence|year=2002|volume=12|issue=2|pages=167–191|doi=10.1111/1532-7795.00030}}</ref> In the final stage, known as commitment, the young adult adopts their sexual identity as a lifestyle. Therefore, this model estimates that the process of coming out begins in childhood, and continues through the early to mid 20s. This model has been contested, and alternate ideas have been explored in recent years.

In terms of [[Philosophy:Sexual identity|sexual identity]], adolescence is when most gay/lesbian and transgender adolescents begin to recognize and make sense of their feelings. Many adolescents may choose to [[Social:Coming out|come out]] during this period of their life once an identity has been formed; many others may go through a period of questioning or denial, which can include experimentation with both homosexual and heterosexual experiences.<ref name="Morrow 2004 91–99">{{cite journal|last=Morrow|first=Deana|title=Social work practice with gay, lesbian, bisexual, and transgender adolescents|journal=Families in Society|date=Jan–Mar 2004|volume=85|issue=1|pages=91–99|doi=10.1606/1044-3894.246}}</ref> A study of 194 lesbian, gay, and bisexual youths under the age of 21 found that having an awareness of one's sexual orientation occurred, on average, around age 10, but the process of coming out to peers and adults occurred around age 16 and 17, respectively.<ref>{{cite journal|last=D'Augelli|first=Anthony|author2=Scott Hershberger|title=Lesbian, gay, and bisexual youth in community settings: Personal challenges and mental health problems|journal=American Journal of Community Psychology|year=1993|volume=21|issue=4|pages=421–448|doi=10.1007/BF00942151}}</ref>  Coming to terms with and creating a positive LGBT identity can be difficult for some youth for a variety of reasons. Peer pressure is a large factor when youth who are questioning their sexuality or [[Philosophy:Gender identity|gender identity]] are surrounded by heteronormative peers and can cause great distress due to a feeling of being different from everyone else. While coming out can also foster better psychological adjustment, the risks associated are real. Indeed, coming out in the midst of a heteronormative peer environment often comes with the risk of ostracism, hurtful jokes, and even violence.<ref name="Morrow 2004 91–99"/>  Because of this, statistically the suicide rate amongst LGBT adolescents is up to four times higher than that of their heterosexual peers due to bullying and rejection from peers or family members.<ref>{{cite web|url=http://gaylife.about.com/od/gayteens/a/gaysuicide.htm |title=Gay, Lesbian, Bisexual, Transgender and Questioning Teen Suicide Statistics - Gay Teen Suicide Statistics |publisher=Gaylife.about.com |date=2012-04-09 |accessdate=2012-09-15}}</ref>

====Self-esteem====
The final major aspect of identity formation is [[Philosophy:Self-esteem|self-esteem]]. Self-esteem is defined as one's thoughts and feelings about one's self-concept and identity.<ref>Marmot, M. (2003) Self-Esteem and Health: Autonomy, Self-Esteem, and Health are Linked Together". British Medical Journal (327) pp. 574-575</ref> Most theories on self-esteem state that there is a grand desire, across all genders and ages, to maintain, protect and enhance their self-esteem.<ref name="sciencedirect.com"/> Contrary to popular belief, there is no empirical evidence for a significant drop in self-esteem over the course of adolescence.<ref>Steinberg, L. (2008). ''Adolescence'', 8th ed. 270. New York, NY: McGraw-Hill.</ref> "Barometric self-esteem" fluctuates rapidly and can cause severe distress and anxiety, but baseline self-esteem remains highly stable across adolescence.<ref>Rosenberg, M. (1986). Self-concept from middle childhood through adolescence. In J. Suls & A. Greenwald (Eds.), ''Psychological perspectives on the self'', Vol. 3. Hillsdale, NJ: Erlbaum.</ref> The validity of global self-esteem scales has been questioned, and many suggest that more specific scales might reveal more about the adolescent experience.<ref>Steinberg, L. (2008). ''Adolescence'', 8th ed. 273. New York, NY: McGraw-Hill.</ref>
Girls are most likely to enjoy high self-esteem when engaged in supportive relationships with friends, the most important function of friendship to them is having someone who can provide social and moral support. When they fail to win friends' approval or couldn't find someone with whom to share common activities and common interests, in these cases, girls suffer from low self-esteem. In contrast, boys are more concerned with establishing and asserting their independence and defining their relation to authority.<ref>"Psychology: The Science of Behaviour" 3rd Canadian Edition</ref><!--citation is inadequately specific e.g. author etc--> As such, they are more likely to derive high self-esteem from their ability to successfully influence their friends; on the other hand, the lack of romantic competence, for example, failure to win or maintain the affection of the opposite or same-sex (depending on sexual orientation), is the major contributor to low self-esteem in adolescent boys. Due to the fact that both men and women happen to have a low self-esteem after ending a romantic relationship, they are prone to other symptoms that is caused by this state. Depression and hopelessness are only two of the various symptoms and it is said that women are twice as likely to experience depression and men are three to four times more likely to commit suicide (Mearns, 1991; Ustun & Sartorius, 1995).<ref>Osvelia Deeds, Jeannette Delgado, Miguel Diego, Tiffany Field, and Martha Pelaez (2009). "Adolescence".</ref>

===Relationships===

====In general====
The relationships adolescents have with their peers, family, and members of their social sphere play a vital role in the social development of an adolescent. As an adolescent's social sphere develops rapidly as they distinguish the differences between friends and acquaintances, they often become heavily emotionally invested in friends.<ref name="Adolescent peer pressure">{{cite web|title=Adolescents and Peer Pressure|publisher=sitemaker.umich.edu/[[Organization:University of Michigan|University of Michigan]]|accessdate=November 6, 2012|url=http://sitemaker.umich.edu/356.darnell/peer_pressure}}</ref> This is not harmful; however, if these friends expose an individual to potentially harmful situations, this is an aspect of [[Social:Peer pressure|peer pressure]]. Adolescence is a critical period in social development because adolescents can be easily influenced by the people they develop close relationships with. This is the first time individuals can truly make their own decisions, which also makes this a sensitive period. Relationships are vital in the social development of an adolescent due to the extreme influence peers can have over an individual. These relationships become significant because they begin to help the adolescent understand the concept of personalities, how they form and why a person has that specific type of personality. "The use of psychological comparisons could serve both as an index of the growth of an implicit personality theory and as a component process accounting for its creation. In other words, by comparing one person's personality characteristics to another's, we would be setting up the framework for creating a general theory of personality (and,&nbsp;... such a theory would serve as a useful framework for coming to understand specific persons)."<ref>{{cite journal|last=Barenboim|first=Carl|title=The Development of Person Perception in Childhood and Adolescence: From Behavioral Comparisons to Psychological Constructs to Psychological Comparisons|journal=Child Development|volume=52|pages=129–144|url=http://0-web.ebscohost.com.helin.uri.edu/ehost/pdfviewer/pdfviewer?vid=3&hid=14&sid=fdbcae39-8efd-4773-976a-e26f2afc32b7%40sessionmgr13|accessdate=8 November 2012|date=1 March 1981|doi=10.2307/1129222|jstor=1129222}}{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> This can be likened to the use of social comparison in developing one's identity and self-concept, which includes ones personality, and underscores the importance of communication, and thus relationships, in one's development. In social comparison we use reference groups, with respect to both psychological and identity development.<ref>Adler, R.B., Rosenfeld, L.B., Proctor, R.F., & Winder, C. (2012). "Interplay: The Process of Interpersonal Communication, Third Canadian Edition" Oxford University Press. pp. 42-45</ref> These reference groups are the peers of adolescents. This means that who the teen chooses/accepts as their friends and who they communicate with on a frequent basis often makes up their reference groups and can therefore have a huge impact on who they become. Research shows that relationships have the largest affect over the social development of an individual.

====Family====
[[File:James Collinson - The Sisters.jpg|thumb|180px|Teenage sisters]]
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,<ref>Grotevant, H. (1997). Adolescent development in family contexts. In N. Eisenberg (Ed.), ''Handbook of child psychology'' (5th ed.), Vol. 3: ''Social, emotional, and personality development'', pp. 1097–1149. New York: Wiley.</ref> when they are increasingly viewed by parents as equals. The adolescent faces the task of increasing independence while preserving a caring relationship with his or her parents.<ref name="Rawlins"/> 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,<ref>{{cite journal | author = Steinberg L|year = 2001| title = We know some things: Adolescent-parent relationships in retrospect and prospect | url = | journal = Journal of Research on Adolescence | volume = 11 | issue = | pages = 1–19 | doi = 10.1111/1532-7795.00001 }}</ref><ref>{{cite web|url=http://family.jrank.org/pages/315/Conflict.html |title=Conflict - Couple Relationships, Family Relationships, Parent-child Relationships - Theory, Development, Children, and Parents - JRank Articles |publisher=Family.jrank.org |accessdate=2012-09-15}}</ref> which adolescents may have previously viewed as issues over which their parents had complete authority.<ref>{{cite journal | author = Smetana J. G. | year = 1988 | title = Adolescents' and parents' conceptions of parental authority | url = | journal = Child Development | volume = 59 | issue = 2| pages = 321–335 | doi = 10.2307/1130313 | pmid = 3359858 | jstor = 1130313 }}</ref> 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. Social media has also played an increasing role in adolescent and parent disagreements.<ref name="Teens Today">{{cite web|url=http://www.theantidrug.com/advice/teens-today/teens-and-technology/social-networking.aspx|archiveurl=https://web.archive.org/web/20121103162953/http://www.theantidrug.com/advice/teens-today/teens-and-technology/social-networking.aspx|archivedate=2012-11-03|title=Social Networking|publisher=theantidrug.com|accessdate=November 6, 2012}}</ref> While parents never had to worry about the threats of social media in the past, it has become a dangerous place for children. While adolescents strive for their freedoms, the unknowns to parents of what their child is doing on social media sites is a challenging subject, due to the increasing amount of predators on social media sites. Many parents have very little knowledge of social networking sites in the first place and this further increases their mistrust. An important challenge for the parent–adolescent relationship is to understand how to enhance the opportunities of online communication while managing its risks.<ref name="sciencedirect.com"/> Although conflicts between children and parents increase during adolescence, these are just relatively minor issues. Regarding their important life issues, most adolescents still share the same attitudes and values as their parents.<ref>{{cite book|author1=Neil R.|author2=Carlson C.|author3=Donald Heth|title=Psychology the Science of Behaviour, 4th Canadian Edition}}</ref>

During childhood, siblings are a source of conflict and frustration as well as a support system.<ref>{{cite journal |vauthors=Lempers J, Clark-Lempers D | year = 1992 | title = Young, middle, and late adolescents; comparisons of the functional importance of five significant relationships | url = | journal = Journal of Youth and Adolescence | volume = 21 | issue = 1| pages = 53–96 | doi = 10.1007/BF01536983 | pmid = 24263682 }}</ref> Adolescence may affect this relationship differently, depending on sibling gender. In same-sex sibling pairs, intimacy increases during early adolescence, then remains stable. Mixed-sex siblings pairs act differently; siblings drift apart during early adolescent years, but experience an increase in intimacy starting at middle adolescence.<ref>{{cite journal |author1=Kim J. |author2=McHale S. M. |author3=Osgood D. W. |author4=Grouter A. C. | year = 2006 | title = Longitudinal course and family correlates of sibling relationships from childhood through adolescence | url = | journal = Child Development | volume = 77 | issue = 6| pages = 1746–1761 | doi = 10.1111/j.1467-8624.2006.00971.x | pmid = 17107458 }}</ref> Sibling interactions are children's first relational experiences, the ones that shape their social and self-understanding for life.<ref>{{cite magazine|author=Marano, Hara Estroff|title=Oh, Brother!|date=July 1, 2010|magazine=Psychology Today|volume=43|issue=4|pages=54–61|publisher=SIRS Researcher|accessdate=25 October 2010|url=https://www.psychologytoday.com/articles/201007/oh-brother}}</ref> 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.

A potential important influence on adolescence is change of the family dynamic, specifically [[Social:Divorce|divorce]]. With the divorce rate up to about 50%,<ref>U.S. Bureau of Labor Statistics, updated and revised from "Families and Work in Transition in 12 Countries,1980–2001," Monthly Labor Review, September 2003</ref> divorce is common and adds to the already great amount of change in adolescence. [[Social:Child custody|Custody]] disputes soon after a divorce often reflect a playing out of control battles and ambivalence between parents. Divorce usually results in less contact between the adolescent and their noncustodial parent.<ref name="Vangelisti">{{Citation |last=Vangelisti |first=A.L. |title= Handbook of family communication |publisher=Lawrence Erlbaum Associates |place=New Jersey |year=2004}}</ref>  In extreme cases of instability and abuse in homes, divorce can have a positive effect on families due to less conflict in the home. However, most research suggests a negative effect on adolescence as well as later development. A recent study found that, compared with peers who grow up in stable post-divorce families, children of divorce who experience additional family transitions during late adolescence, make less progress in their math and social studies performance over time.<ref>{{cite journal |author1=Sun Y. |author2=Li Y. | year = 2009 | title = Postdivorce family stability and changes in adolescents' academic performance: A growth-curve model | url = | journal = Journal of Family Issues | volume = 30 | issue = 11| pages = 1527–1555 | doi=10.1177/0192513x09339022 }}</ref> Another recent study put forth a new theory entitled the adolescent epistemological trauma theory,<ref name="Ziemer"/> which posited that traumatic life events such as parental divorce during the formative period of late adolescence portend lifelong effects on adult conflict behavior that can be mitigated by effective behavioral assessment and training.<ref name="Ziemer">{{cite thesis|author=Ziemer, B. S.|year=2012|url=http://search.proquest.com/docview/1018397533|title=Epistemological effects of divorce during adolescence on adult conflict behavior|publisher=Nova Southeastern University}} ProQuest Dissertations and Theses, 262.</ref> A parental divorce during childhood or adolescence continues to have a negative effect when a person is in his or her twenties and early thirties. These negative effects include romantic relationships and conflict style, meaning as adults, they are more likely to use the styles of avoidance and competing in conflict management.<ref>{{cite journal |author1=Cherlin Andrew J. |author2=Chase-Lansdale P. Lindsay |author3=McRaeAmerican Christine | year = 1998 | title = Effects of Parental Divorce on Mental Health Throughout the Life Course | url = | journal = Sociological Review | volume = 63 | issue = 2| pages = 239–249 | doi=10.2307/2657325}}</ref>

Despite changing family roles during adolescence, the home environment and parents are still important for the behaviors and choices of adolescents.<ref name="trends">{{cite web|archiveurl=https://web.archive.org/web/20060822130027/http://www.childtrends.org/Files/FamilyEnvironmentRB.pdf|title=The Family Environment and Adolescent Well-being: Exposure to Positive and Negative Family Influences|archivedate=2006-08-22|url=http://www.childtrends.org/Files/FamilyEnvironmentRB.pdf|date=June 2006|publisher=NAHIC|author1=Aufseeser, Dena|author2=Jekielek, Susan|author3=Brown, Brett}}</ref> 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 [[Biology:Sexual intercourse|sexual intercourse]].<ref name = "trends" />
In addition, parents influence the education of adolescence. A study conducted by Adalbjarnardottir and Blondal (2009) showed that adolescents at the age of 14 who identify their parents as authoritative figures are more likely to complete secondary education by the age of 22—as support and encouragement from an authoritative parent motivates the adolescence to complete schooling to avoid disappointing that parent.<ref>{{cite journal |author1=Adalbjarnardottir S. |author2=Blondal K.S. | year = 2009 | title = Parenting practices and school dropout: a longitudinal study | url = | journal = Adolescence | volume = 44 | issue = | page = 176 }}</ref>

====Peers====
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Peer groups are essential to social and general development. Communication with peers increases significantly during adolescence and peer relationships become more intense than in other stages<ref>Papalia, D.E., Olds, S.W., Feldman, R.D., & Kruk, R. (2004). ''A Child's World: Infancy through Adolescence (First Canadian Ed.)'' McGraw-Hill Ryerson Ltd. pp. 444-451</ref> and more influential to the teen, affecting both the decisions and choices being made.<ref name="Swanson">{{Citation |last1= Swanson |first1= D.P. |last2=Edwards |first2=M.C. |last3=Spencer |first3=M.B. |title=Adolescence: Development during a global era |publisher=Elsevier Academic Press |place= Boston |year=2010}}</ref> High quality friendships may enhance children's development regardless of the characteristics of those friends. As children begin to bond with various people and create friendships, it later helps them when they are adolescent and sets up the framework for adolescence and peer groups.<ref>{{cite journal|last=Berndt|first=Thomas J.|title=Friendship Quality and Social Development | journal = Current Directions in Psychological Science|date=February 2002|volume=11|issue=1|pages=7–10|doi=10.1111/1467-8721.00157}}</ref>
[[Social:Peer group|Peer group]]s are especially important during adolescence, a period of development characterized by a dramatic increase in time spent with peers<ref>{{cite journal |author1=Larson R. |author2=Richards M. |year = 1991 | title = Daily companionship in late childhood and early adolescence: Changing developmental contexts | url = | journal = Child Development | volume = 62 | issue = 2| pages = 284–300 | doi = 10.2307/1131003 | pmid = 2055123}}</ref> and a decrease in adult supervision.<ref>Brown, B. (1990). Peer groups. In S. Feldman & G. Elliot (Eds.), ''At the threshold: The developing adolescent'', pp.&nbsp;171–196. Cambridge, MA: Harvard University Press.</ref> Adolescents also associate with friends of the opposite sex much more than in childhood<ref>Brown, B. (2004). Adolescents' relationships with peers. In R. Lerner & L. Steinberg (Eds.), ''Handbook of adolescent psychology''. New York: Wiley.</ref> and tend to identify with larger groups of peers based on shared characteristics.<ref>{{cite journal | author = Eder D | year = 1985 | title = The cycle of popularity: Interpersonal relations among female adolescence | url = | journal = Sociology of Education | volume = 58 | issue = 3| pages = 154–165 | doi = 10.2307/2112416 | jstor = 2112416 }}</ref> It is also common for adolescents to use friends as coping devices in different situations.<ref>How do Young Adolescents Cope With Social Problems? An Examination of Social Goals, Coping With Friends, and Social Adjustment. ''Journal of Early Adolescence''.</ref> A three-factor structure of dealing with friends including avoidance, mastery, and nonchalance has shown that adolescents use friends as coping devices with social stresses.

Communication within peer groups allows adolescents to explore their feelings and identity as well as develop and evaluate their social skills. Peer groups offer members the opportunity to develop social skills such as empathy, sharing, and leadership. Adolescents choose peer groups based on characteristics similarly found in themselves.<ref name="Rawlins"/> By utilizing these relationships, adolescents become more accepting of who they are becoming. Group norms and values are incorporated into an adolescent's own self-concept.<ref name="Swanson"/> Through developing new communication skills and reflecting upon those of their peers, as well as self-opinions and values, an adolescent can share and express emotions and other concerns without fear of rejection or judgment. Peer groups can have positive influences on an individual, such as on academic motivation and performance. However, while peers may facilitate social development for one another they may also hinder it. Peers can have negative influences, such as encouraging experimentation with drugs, drinking, vandalism, and stealing through peer pressure.<ref>{{cite web|url=http://www.minddisorders.com/Ob-Ps/Peer-groups.html |title=Peer groups - children, therapy, adults, drug, people, skills, effect, women |publisher=Minddisorders.com |accessdate=2012-09-15}}</ref> Susceptibility to peer pressure increases during early adolescence, peaks around age 14, and declines thereafter.<ref>{{cite journal|pmid=18020830|year=2007|last1=Steinberg|first1=L|last2=Monahan|first2=KC|title=Age Differences in Resistance to Peer Influence|volume=43|issue=6|pages=1531–43|doi=10.1037/0012-1649.43.6.1531|pmc=2779518|journal=Developmental Psychology}}</ref> Further evidence of peers hindering social development has been found in Spanish teenagers, where emotional (rather than solution-based) reactions to problems and emotional instability have been linked with physical aggression against peers.<ref>{{cite journal |author1=Carlo G. |author2=Mestre M. V. |author3=McGinley M. M. |author4=Samper P. |author5=Tur A. |author6=Sandman D. | year = 2012 | title = The interplay of emotional instability, empathy, and coping on prosocial and aggressive behaviors | url = | journal = Personality and Individual Differences | volume = 53 | issue = 5| pages = 675–680 | doi=10.1016/j.paid.2012.05.022}}</ref> Both [[Social:Assault|physical]] and [[Social:Relational aggression|relational]] aggression are linked to a vast number of enduring psychological difficulties, especially depression, as is [[Social:Social rejection|social rejection]].<ref>{{cite journal |author1=French D. |author2=Conrad J. | year = 2001 | title = School dropout as predicted by peer rejection and antisocial behavior | url = | journal = Journal of Research on Adolescence | volume = 11 | issue = 3| pages = 225–244 | doi = 10.1111/1532-7795.00011 }}</ref> Because of this, bullied adolescents often develop problems that lead to further victimization.<ref>{{cite journal | vauthors = Hodges E, Perry D | year = 1999 | title = Personal and interpersonal antecedents and consequences of victimization by peers | url = | journal = Journal of Personality and Social Psychology | volume = 76 | issue = 4| pages = 677–685 | doi = 10.1037/0022-3514.76.4.677 | pmid = 10234851 }}</ref> Bullied adolescents are more likely to both continue to be bullied and to bully others in the future.<ref>{{cite journal |author1=Jose P. E. |author2=Kljakovic M. |author3=Scheib E. |author4=Notter O. | year = 2012 | title = The Joint Development of Traditional Bullying and Victimization With Cyber Bullying and Victimization in Adolescence | url = | journal = Journal of Research on Adolescence | volume = 22 | issue = 2| pages = 301–309 | doi = 10.1111/j.1532-7795.2011.00764.x }}</ref> However, this relationship is less stable in cases of cyberbullying, a relatively new issue among adolescents.

Adolescents tend to associate with "cliques" on a small scale and "crowds" on a larger scale. During early adolescence, adolescents often associate in [[Social:Adolescent cliques|cliques]], exclusive, single-sex groups of peers with whom they are particularly close. Despite the common{{According to whom|date=April 2016}} notion that cliques are an inherently negative influence, they may help adolescents become socially acclimated and form a stronger sense of identity. Within a clique of highly athletic male-peers, for example, the clique may create a stronger sense of fidelity and competition. Cliques also have become somewhat a "collective parent", i.e. telling the adolescents what to do and not to do.<ref>Grier, Peter. "The Heart of a High School: Peers As Collective Parent." ''Christian Science Monitor''. 24 April 2000: n.p. ''SIRS Researcher''. Web. 25 October 2010.</ref> Towards late adolescence, cliques often merge into mixed-sex groups as teenagers begin romantically engaging with one another.<ref name="Connolly J 2004">{{cite journal |author1=Connolly J. |author2=Craig W. |author3=Goldberg A. |author4=Pepler D. | year = 2004 | title = Mixed-gender groups, dating, and romantic relationships in early adolescence | url = | journal = Journal of Research on Adolescence | volume = 14 | issue = 2| pages = 185–207 | doi = 10.1111/j.1532-7795.2004.01402003.x }}</ref> These small friend groups then break down further as socialization becomes more couple-oriented. 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, such as jocks or [[Philosophy:Nerd|nerd]]s. In large, multi-ethnic high schools, there are often ethnically determined crowds.<ref>Brown, B., & Mounts, N. (1989, April). "Peer groups structures in single versus multiethnic high schools". Paper presented at the biennial meetings of the Society for Research on Adolescence, San Diego.</ref> While crowds are very influential during early and middle adolescence, they lose salience during high school as students identify more individually.<ref>Larkin, R.W. (1979). ''Suburban youth in cultural crisis''. New York: Oxford.</ref>

An important aspect of communication is the channel used. ''Channel'', in this respect, refers to the form of communication, be it face-to-face, email, text message, phone or other. Teens are heavy users of newer forms of communication such as text message and social-networking websites such as Facebook, especially when communicating with peers.<ref name="Subrahmanyam">{{Cite journal|last=Subrahmanyam| first=Kaveri | last2=Greenfield| first2=Patricia|date= Spring 2008|title= Online Communication and Adolescent Relationships|journal= The Future of Children| volume=18|pages=119–146| doi=10.1353/foc.0.0006}}</ref> Adolescents use online technology to experiment with emerging identities and to broaden their peer groups, such as increasing the amount of friends acquired on Facebook and other social media sites.<ref name="Swanson"/> Some adolescents use these newer channels to enhance relationships with peers however there can be negative uses as well such as cyberbullying, as mentioned previously, and negative impacts on the family.<ref name="Subrahmanyam"/>

====Romance and sexual activity====
[[Social:Intimate relationship|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.<ref name="Carver K. 2003">Carver K., Joyner K., Udry J.R. (2003). National estimates of adolescent romantic relationships. In ''Adolescent Romantic Relationships and Sexual Behavior: Theory, Research, and Practical Implications'', 291–329.</ref> 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 {{wipe|United Kingdom}}.<ref name="sex stats">{{cite web|url=http://sexperienceuk.channel4.com/teen-sex-survey|title=Teen Sex Survey|accessdate=2008-09-11|publisher=Channel 4|year=2008| archiveurl= https://web.archive.org/web/20080912225248/http://sexperienceuk.channel4.com/teen-sex-survey| archivedate= 12 September 2008 <!--DASHBot-->| deadurl= no}}</ref> 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.<ref>{{cite web|url=http://www.newstrategist.com/productdetails/Sex.SamplePgs.pdf|archiveurl=https://web.archive.org/web/20061120093911/http://www.newstrategist.com/productdetails/Sex.SamplePgs.pdf|archivedate=2006-11-20 |title=Seventeen Is the Average Age at First Sexual Intercourse, '&#39;American Sexual Behavior'&#39;, p.4-5 |format=PDF |accessdate=2012-09-15}}</ref> 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 [[Biology:Sexual maturity|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.<ref>Allen, J., & Land, D. (1999). Attachment in adolescence. In J. Cassidy & P. Shaver (Eds.), ''Handbook of attachment theory and research.'' New York: Guilford Press.</ref> Long-term relationships allow adolescents to gain the skills necessary for high-quality relationships later in life<ref>Madsen S., Collins W. A. (2005). Differential predictions of young adult romantic
relationships from transitory vs. longer romantic experiences during adolescence. Presented at ''Biennial Meeting of the Society for Research on Child Development'', Atlanta, GA.</ref> 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<ref>Seiffge-Krenke I., Lang J. (2002). Forming and maintaining romantic relations
from early adolescence to young adulthood: evidence of a developmental sequence. Presented at ''Biennial Meeting of the Society for Research on Adolescence'', 19th, New Orleans, LA.</ref> and are positively associated with self-esteem, self-confidence, and social competence.<ref>{{cite journal |author1=Pearce M. J. |author2=Boergers J. |author3=Prinstein M.J. |year = 2002 | title = Adolescent obesity, overt and relational peer victimization, and romantic relationships | url = | journal = Obesity Research | volume = 10 | issue = 5| pages = 386–93 | doi = 10.1038/oby.2002.53 | pmid = 12006638 }}</ref><ref>{{cite journal |author1=Zimmer-Gembeck M.J. |author2=Siebenbruner J. |author3=Collins W.A. | year = 2004 | title = A prospective study of intraindividual and peer influences on adolescents' heterosexual romantic and sexual behavior | url = | journal = Archives of Sexual Behavior | volume = 33 | issue = 4| pages = 381–394 | doi = 10.1023/B:ASEB.0000028891.16654.2c | pmid = 15162084 }}</ref> For example, an adolescent with positive self-confidence is likely to consider themselves a more successful partner, whereas negative experiences may lead to low confidence as a romantic partner.<ref>Furman, W. & Shafer, L. (2003) The role of romantic relationships in adolescent development.http://www.du.edu/psychology/relationshipcenter/publications/furman_shaffer_2003.pdf</ref> Adolescents often date within their demographic in regards to race, ethnicity, popularity, and physical attractiveness.<ref>{{cite journal | last1 = Simon | first1 = V. A. | last2 = Aikins | first2 = J. W. | last3 = Prinstein | first3 = M. J. | year = 2008 | title = Romantic partner selection and socialization during early adolescence | url = | journal = Child Dev. | volume =  | issue = | page =  }}</ref> 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.<ref name="Carver K. 2003"/>

Some researchers are now focusing on learning about how adolescents view their own relationships and sexuality; they want to move away from a research point of view that focuses on the problems associated with adolescent sexuality.{{why|This sounds pov, in itself without an explanation|date=April 2014}} College Professor Lucia O'Sullivan and her colleagues found that there were no significant gender differences in the relationship events adolescent boys and girls from grades 7-12 reported.<ref name="O'Sullivan">{{cite journal | authors = O'Sullivan L. F., Cheng M., Brooks-Gunn J., Mantsun K. Harris | year = 2007 | title = I wanna hold your hand: The progression of social, romantic and sexual events in adolescent relationships | url = | journal = Perspectives on Sexual and Reproductive Health | volume = 39 | issue = 2| pages = 100–107 | doi = 10.1363/3910007 | pmid = 17565623 }}</ref> Most teens said they had kissed their partners, held hands with them, thought of themselves as being a couple and told people they were in a relationship. This means that private thoughts about the relationship as well as public recognition of the relationship were both important to the adolescents in the sample. Sexual events (such as sexual touching, sexual intercourse) were less common than romantic events (holding hands) and social events (being with one's partner in a group setting). The researchers state that these results are important because the results focus on the more positive aspects of adolescents and their social and romantic interactions rather than focusing on sexual behavior and its consequences.<ref name="O'Sullivan" />

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.<ref>{{cite journal |author1=Manning W. |author2=Longmore M. |author3=Giordano P. | year = 2000 | title = The relationship context of contraceptive use at first intercourse | url = | journal = Family Planning Perspectives | volume = 32 | issue = 3| pages = 104–110 | doi = 10.2307/2648158 | pmid = 10894255 }}</ref> Adolescents can use technologies and social media to seek out romantic relationships as they feel it is a safe place to try out dating and identity exploration. From these social media encounters, a further relationship may begin.<ref name="Swanson"/> 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.<ref>{{cite journal |author1=Welsh D. P. |author2=Haugen P. T. |author3=Widman L. |author4=Darling N. |author5=Grello C. M. | year = 2005 | title = Kissing is good: a developmental investigation of sexuality in adolescent romantic couples | url = | journal = Sexuality Research and Social Policy | volume = 2 | issue = 4| pages = 32–41 | doi = 10.1525/srsp.2005.2.4.32 }}</ref><ref>{{cite journal |author1=Williams T. |author2=Connolly J. |author3=Cribbie R. | year = 2008 | title = Light and heavy heterosexual activities of young Canadian adolescents: normative patterns and differential predictors | url = | journal = Journal of Research on Adolescence | volume = 18 | issue = | pages = 145–72 | doi = 10.1111/j.1532-7795.2008.00554.x }}</ref> This effect does not hold true for sexual activity in late adolescence that takes place within a romantic relationship.<ref>{{cite journal |author1=Grello C. M. |author2=Welsh D. P. |author3=Harper MS |author4=Dickson J. | year = 2003 | title = Dating and sexual relationship trajectories and adolescent functioning | url = | journal = Adolescent & Family Health | volume = 3 | issue = | pages = 103–12 }}</ref> Some research suggest that there are genetic causes of early sexual activity that are also risk factors for [[Medicine:Juvenile delinquency|delinquency]], suggesting that there is a group who are at risk for both early sexual activity and emotional distress. For older adolescents, though, sexual activity in the context of romantic relationships was actually correlated with lower levels of deviant behavior after controlling for genetic risks, as opposed to sex outside of a relationship (hook-ups)<ref>{{cite journal |author1=Harden K. |author2=Mendle J. | year = 2011 | title = Adolescent sexual activity and the development of delinquent behavior: The role of relationship context | url = | journal = Journal of Youth and Adolescence | volume = 40 | issue = 7| pages = 825–838 | doi = 10.1007/s10964-010-9601-y }}</ref>

Dating violence is fairly prevalent within adolescent relationships. When surveyed, 10-45% of adolescents reported having experienced physical violence in the context of a relationship while a quarter to a third 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. In heterosexual couples, there is no significant difference between the rates of male and female aggressors, unlike in adult relationships.<ref>{{cite journal |author1=Halpern C. |author2=Oslak S. |author3=Young M. |author4=Martin S. |author5=Kupper L. | year = 2001 | title = Partner violence among adolescents in opposite-sex romantic: Findings from the National Longitudinal Study of Adolescent Health | url = | journal = American Journal of Public Health | volume = 91 | issue = 10| pages = 1679–1685 | doi = 10.2105/AJPH.91.10.1679 | pmid = 11574335 | pmc = 1446854 }}</ref><ref>{{cite journal |author1=Halpern C. |author2=Young M. |author3=Waller M. |author4=Martin S. |author5=Kupper L. | year = 2004 | title = Prevalence of partner violence in same-sex romantic and sexual relationships in a national sample of adolescents | url = | journal = Journal of Adolescent Health | volume = 35 | issue = 2| pages = 124–131 | pmid = 15261641 | doi = 10.1016/j.jadohealth.2003.09.003 }}</ref><ref name="Collins2009">{{cite journal |author1=Collins W. A. |author2=Welsh D. P. |author3=Furman W. | year = 2009 | title = Adolescent romantic relationships | url = | journal = Annual Review of Psychology | volume = 60 | issue = 1| pages = 631–652 | doi = 10.1146/annurev.psych.60.110707.163459 | pmid = 19035830 }}</ref>

Adolescent girls with male partners who are older than them are at higher risk for adverse sexual health outcomes than their peers. Research suggests that the larger the partner age difference, the less relationship power the girls experience. Behavioral interventions such as developing relationship skills in identifying, preventing, and coping with controlling behaviors may be beneficial. For condom use promotion, it is important to identify decision-making patterns within relationships and increase the power of the adolescent female in the relationship.<ref>Volpe EM, Hardie T, Cerulli C, Sommers MS, Morrison-Beedy D. What's age got to do with it? Partner age difference, power, intimate partner violence, and sexual risk in urban adolescents. Journal of Interpersonal Violence, 2013; 28(10): 2068-2087</ref> Female adolescents from minority populations are at even higher risk for intimate partner violence (IPV). Recent research findings suggest that a substantial portion of young urban females are at high risk for being victims of multiple forms of IPV. Practitioners diagnosing depression among urban minority teens should assess for both physical and non-physical forms of IPV, and early detection can help to identify youths in need of intervention and care.<ref>Teitelman AM, Ratcliffe SJ, McDonald CC, Brawner BM, Sullivan C. Relationships between physical and non-physical forms of intimate partner violence and depression among urban minority adolescent females. Child and Adolescent Mental Health, 2011; 16(2): 92-100</ref><ref>Volpe EM, Morales-Aleman MM, Teitelman AM. Urban adolescent girls’ perspectives on romantic relationships: Initiation, involvement, negotiation and conflict. Issues in Mental Health Nursing, 2014; 35: 776-790</ref> Similarly to adult victims, adolescent victims do not readily disclose abuse, and may seek out medical care for problems not directly related to incidences of IPV. Therefore, screening should be a routine part of medical treatment for adolescents regardless of chief complaint. Many adults discount instances of IPV in adolescents or believe they do not occur because relationships at young ages are viewed as “puppy love,” however, it is crucial that adults take IPV in adolescents seriously even though often policy falls behind.<ref>Thomas KA, Sorenson SB, Joshi M. Police-documented incidents of intimate partner violence against young women. Journal of Women's Health, 2010; 19: 1079-1087</ref>

In contemporary society, adolescents also face some risks as their sexuality begins to transform. While some of these, such as emotional distress (fear of abuse or exploitation) and sexually transmitted infections/diseases (STIs/STDs), including HIV/AIDS, are not necessarily inherent to adolescence, others such as teenage pregnancy (through non-use or failure of contraceptives) are seen as social problems in most western societies. One in four sexually active teenagers will contract an STI.<ref name="Mulrine, A 2010">Mulrine, A."Risky Business." U.S. News & World Report. 27 May 2002: 42-49. SIRS Researcher. Web. 25 Oct 2010.</ref> Adolescents in the United States often chose "anything but intercourse" for sexual activity because they mistakenly believe it reduces the risk of STIs. Across the country, clinicians report rising diagnoses of [[Medicine:Herpes simplex|herpes]] and human papillomavirus (HPV), which can cause genital warts, and is now thought to affect 15 percent of the teen population. Girls 15 to 19 have higher rates of gonorrhea than any other age group. One-quarter of all new HIV cases occur in those under the age of 21.<ref name="Mulrine, A 2010"/> Multrine also states in her article that according to a March survey by the Kaiser Family Foundation, eighty-one percent of parents want schools to discuss the use of condoms and contraception with their children. They also believe students should be able to be tested for STIs. Furthermore, teachers want to address such topics with their students. But, although 9 in 10 sex education instructors across the country believe that students should be taught about contraceptives in school, over one quarter report receiving explicit instructions from school boards and administrators not to do so. According to anthropologist Margaret Mead, 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.

==Culture==

===Summary===
[[File:Japan08.07 Shibuya Mybestfriends.jpg|thumb|Japanese ''gyaru'' girls in Tokyo]]
There are certain characteristics of adolescent development that are more rooted in culture than in human biology or cognitive structures. [[Social:Culture|Culture]] has been defined as the "symbolic and behavioral inheritance received from the past that provides a community framework for what is valued".<ref>{{cite book|last=Lerner|first=J.V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara.|isbn=1576072053|page=807|author2=Lerner, R.M. |author3= Finkelstein, J.}}</ref>  Culture is learned and socially shared, and it affects all aspects of an individual's life.<ref name="Lerner 2001 807">{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=807|author2=Rosenberg, Richard M. |author3= Jordan Finkelstein |others= Mark L.}}</ref>  Social responsibilities, sexual expression, and belief system development, for instance, are all things that are likely to vary by culture. Furthermore, distinguishing characteristics of youth, including dress, music and other uses of media, employment, art, food and beverage choices, recreation, and language, all constitute a [[Social:Youth culture|youth culture]].<ref name="Lerner 2001 807"/>  For these reasons, culture is a prevalent and powerful presence in the lives of adolescents, and therefore we cannot fully understand today's adolescents without studying and understanding their culture.<ref name="Lerner 2001 807"/> However, "culture" should not be seen as synonymous with nation or ethnicity. Many cultures are present within any given country and racial or socioeconomic group. Furthermore, to avoid [[Social:Ethnocentrism|ethnocentrism]], researchers must be careful not to define the culture's role in adolescence in terms of their own cultural beliefs.<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=271|author2=Rosenberg, Richard M. |editor= Jordan Finkelstein |others= Mark L.}}</ref>

In Britain, teenagers first came to public attention during the Second World War, when there were fears of juvenile delinquency.<ref>Melanie Tebbutt, ''Making Youth: A History of Youth in Modern Britain'' (2016).</ref> By the 1950s, the media presented teenagers in terms of generational rebellion.  The exaggerated moral panic among politicians and the older generation was typically belied by the growth in intergenerational cooperation between parents and children. Many working-class parents, enjoying newfound economic security, eagerly took the opportunity to encourage their teens to enjoy more adventurous lives.<ref>Selina Todd, and Hilary Young. "Baby-Boomers to ‘Beanstalkers’ Making the Modern Teenager in Post-War Britain." ''Cultural and Social History'' 9#3 (2012): 451-467.</ref>  Schools were falsely portrayed as dangerous blackboard jungles under the control of rowdy kids.<ref>Laura Tisdall,  "Inside the ‘blackboard jungle’ male teachers and male pupils at English secondary modern schools in fact and fiction, 1950 to 1959." ''Cultural and Social History'' 12.4 (2015): 489-507.</ref> The media distortions of the teens as too affluent, and as promiscuous, delinquent, counter-cultural rebels do not reflect the actual experiences of ordinary young adults, particularly young women.<ref>Helena Mills, "Using the personal to critique the popular: women’s memories of 1960s youth." ''Contemporary British History'' 30#4 (2016): 463-483.</ref>

===Autonomy===
The degree to which adolescents are perceived as autonomous beings varies widely by culture, as do the behaviors that represent this emerging autonomy. Psychologists have identified three main types of [[Autonomy|autonomy]]: emotional independence, behavioral autonomy, and cognitive autonomy.<ref name="Lerner 2001 79">{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=79|editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= foreword by Mark L.}}</ref>  Emotional autonomy is defined in terms of an adolescent's relationships with others, and often includes the development of more mature emotional connections with adults and peers.<ref name="Lerner 2001 79"/>  Behavioral autonomy encompasses an adolescent's developing ability to regulate his or her own behavior, to act on personal decisions, and to self-govern. Cultural differences are especially visible in this category because it concerns issues of dating, social time with peers, and time-management decisions.<ref name="Lerner 2001 79"/>  Cognitive autonomy describes the capacity for an adolescent to partake in processes of independent reasoning and decision-making without excessive reliance on social validation.<ref name="Lerner 2001 79"/>  Converging influences from adolescent cognitive development, expanding social relationships, an increasingly adultlike appearance, and the acceptance of more rights and responsibilities enhance feelings of autonomy for adolescents.<ref name="Lerner 2001 79"/>  Proper development of autonomy has been tied to good mental health, high self-esteem, self-motivated tendencies, positive self-concepts, and self-initiating and regulating behaviors.<ref name="Lerner 2001 79"/>  Furthermore, it has been found that adolescents' mental health is best when their feelings about autonomy match closely with those of their parents.<ref>Juang, L., Lerner, J. McKinney, J., & von Eye, A. (1999)</ref>

A questionnaire called the teen timetable has been used to measure the age at which individuals believe adolescents should be able to engage in behaviors associated with autonomy.<ref name="Steinberg, L. 2011">Steinberg, L. (2011). "Adolescence," 9th ed. 292. New York, NY: McGraw-Hill.</ref> This questionnaire has been used to gauge differences in cultural perceptions of adolescent autonomy, finding, for instance, that White parents and adolescents tend to expect autonomy earlier than those of Asian descent.<ref name="Steinberg, L. 2011"/>  It is, therefore, clear that cultural differences exist in perceptions of adolescent autonomy, and such differences have implications for the lifestyles and development of adolescents. In sub-Saharan African youth, the notions of individuality and freedom may not be useful in understanding adolescent development. Rather, African notions of childhood and adolescent development are relational and interdependent.<ref name="The World's Youth">{{cite book|last1=Brown|first1=B. Bradford|last2=W. Larson|first2=Reed|last3=Saraswathi|first3=T.S.|first4=A. Bame|last4=Nsamenang|title=The World's Youth: Adolescence in Eight Regions of the Globe|date=2002|publisher=Cambridge University Press|page=69|url=http://assets.cambridge.org/97805218/09108/sample/9780521809108ws.pdf|accessdate=11 September 2014|chapter=3}}</ref>

===Social roles and responsibilities===
[[File:Alessandro Allori 003.jpg|thumb|180px|Portrait of a noble girl c. 1571]]
The lifestyle of an adolescent in a given culture is profoundly shaped by the roles and responsibilities he or she is expected to assume. The extent to which an adolescent is expected to share family responsibilities is one large determining factor in normative adolescent behavior. For instance, adolescents in certain cultures are expected to contribute significantly to household chores and responsibilities.<ref name="Lerner 2001 115">{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=115|editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref> Household chores are frequently divided into self-care tasks and family-care tasks. However, specific household responsibilities for adolescents may vary by culture, family type, and adolescent age.<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=116 |editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref> Some research has shown that adolescent participation in family work and routines has a positive influence on the development of an adolescent's feelings of self-worth, care, and concern for others.<ref name="Lerner 2001 115"/> 	

In addition to the sharing of household chores, certain cultures expect adolescents to share in their family's financial responsibilities. According to family economic and financial education specialists, adolescents develop sound money management skills through the practices of saving and spending money, as well as through planning ahead for future economic goals.<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=44|editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref> Differences between families in the distribution of financial responsibilities or provision of [[Finance:Allowance (money)|allowance]] may reflect various social background circumstances and intrafamilial processes, which are further influenced by cultural norms and values, as well as by the business sector and market economy of a given society.<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|pages=44–45|editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref> For instance, in many developing countries it is common for children to attend fewer years of formal schooling so that, when they reach adolescence, they can begin working.<ref>Larson, R., & Verma, S. (1999). How children and adolescents spend their time: Time budgest for locations, activities, and companionship. "American Journal of Community Psychology, 29", 565-597.</ref>

While adolescence is a time frequently marked by participation in the workforce, the number of adolescents in the workforce is much lower now than in years past as a result of increased accessibility and perceived importance of formal higher education.<ref name="National Research Council 2005">National Research Council. (2005). "Growing up global". Washington, DC: National Academy Press.</ref> For example, half of all 16-year-olds in China were employed in 1980, whereas less than one fourth of this same cohort were employed in 1990.<ref name="National Research Council 2005"/>	
 	
Furthermore, the amount of time adolescents spend on work and leisure activities varies greatly by culture as a result of cultural norms and expectations, as well as various socioeconomic factors. American teenagers spend less time in school or working and more time on leisure activities—which include playing sports, socializing, and caring for their appearance—than do adolescents in many other countries.<ref name="Larson, R. 1990">{{cite journal |author1=Larson R. |author2=Verma S. | year = 1999 | title = How children and adolescents spend time across the world:Work, play, and developmental opportunities | url = | journal = Psychological Bulletin | volume = 125 | issue = 6| pages = 701–736 | pmid = 10589300 | doi=10.1037/0033-2909.125.6.701}}</ref> These differences may be influenced by cultural values of education and the amount of responsibility adolescents are expected to assume in their family or community.

Time management, financial roles, and social responsibilities of adolescents are therefore closely connected with the education sector and processes of career development for adolescents, as well as to cultural norms and social expectations. In many ways, adolescents' experiences with their assumed social roles and responsibilities determine the length and quality of their initial pathway into adult roles.<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=101 |editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref>

===Belief system development===
Adolescence is frequently characterized by a transformation of an adolescent's understanding of the world, the rational direction towards a life course, and the active seeking of new ideas rather than the unquestioning acceptance of adult authority.<ref name="Lerner 2001 577">{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=577 |editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref>  An adolescent begins to develop a unique belief system through his or her interaction with social, familial, and cultural environments.<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|pages=577–579 |editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref>  While organized religion is not necessarily a part of every adolescent's life experience, youth are still held responsible for forming a set of beliefs about themselves, the world around them, and whatever higher powers they may or may not believe in.<ref name="Lerner 2001 577"/> This process is often accompanied or aided by cultural traditions that intend to provide a meaningful transition to adulthood through a ceremony, ritual, confirmation, or [[Religion:Rite of passage|rite of passage]].<ref>{{cite book|last=Lerner|first=Jacqueline V.|title=Adolescence in America : an encyclopedia|year=2001|publisher=ABC-CLIO|location=Santa Barbara, Calif.|isbn=1576072053|page=578 |editor=Rosenberg, Richard M. |editor2= Jordan Finkelstein |others= Mark L.}}</ref>

===Sexuality===
Many cultures define the transition into adultlike sexuality by specific biological or social milestones in an adolescent's life. For example, [[Biology:Menarche|menarche]] (the first menstrual period of a female), or semenarche (the first ejaculation of a male) are frequent sexual defining points for many cultures. In addition to biological factors, an adolescent's sexual socialization is highly dependent upon whether their culture takes a restrictive or permissive attitude toward teen or premarital sexual activity. In the United States specifically, adolescents are said to have "raging hormones" that drive their sexual desires. These sexual desires are then dramatized regarding teen sex and seen as "a site of danger and risk; that such danger and risk is a source of profound worry among adults".<ref>[Fields, J. (2012). Sexuality Education in the United States: Shared Cultural Ideas across a Political Divide. Retrieved April 28, 2016.]</ref> There is little to no normalization regarding teenagers having sex in the U.S., which causes conflict in how adolescents are taught about sex education. There is a constant debate about whether abstinence-only sex education or comprehensive sex education should be taught in schools and this stems back to whether or not the country it is being taught in is permissive or restrictive. Restrictive cultures overtly discourage sexual activity in unmarried adolescents or until an adolescent undergoes a formal rite of passage. These cultures may attempt to restrict sexual activity by separating males and females throughout their development, or through public shaming and physical punishment when sexual activity does occur.<ref name="Connolly J 2004"/><ref name="Ford, C. 1951">Ford, C. & Beach, F. (1951). "Patterns of sexual behavior". New York: Harper & Row.</ref> In less restrictive cultures, there is more tolerance for displays of adolescent sexuality, or of the interaction between males and females in public and private spaces. Less restrictive cultures may tolerate some aspects of adolescent sexuality, while objecting to other aspects. For instance, some cultures find teenage sexual activity acceptable but teenage pregnancy highly undesirable. Other cultures do not object to teenage sexual activity or teenage pregnancy, as long as they occur after marriage.<ref name="ReferenceB">Steinberg, L. (2011). "Adolescence", 9th ed. New York, NY: McGraw-Hill.</ref> In permissive societies, overt sexual behavior among unmarried teens is perceived as acceptable, and is sometimes even encouraged.<ref name="ReferenceB"/> Regardless of whether a culture is restrictive or permissive, there are likely to be discrepancies in how females versus males are expected to express their sexuality. Cultures vary in how overt this double standard is—in some it is legally inscribed, while in others it is communicated through social convention.<ref>Diamond, L., Savin- Williams, R. (2009). Adolescent Sexuality. In R. Lerner & L. Steinberg (Eds.), "Handbook of adolescent psychology" (3rd ed., Vol. 1, pp.&nbsp;479–523). New York: Wiley.</ref> Lesbian, gay, bisexual and transgender youth face much discrimination through bullying from those unlike them and may find telling others that they are gay to be a traumatic experience.<ref>Furlong, Andy (2013). "Youth Studies", New York, NY: Routledge.</ref> The range of sexual attitudes that a culture embraces could thus be seen to affect the beliefs, lifestyles, and societal perceptions of its adolescents.

===Legal issues, rights and privileges===

====General issues====
[[File:2009-04-13 Cherry Pie sign.jpg|thumb|A sign outside a sex shop reads "Must Be 18 To Enter" in Chapel Hill, North Carolina.]]
Adolescence is a period frequently marked by increased rights and privileges for individuals. While cultural variation exists for legal rights and their corresponding ages, considerable consistency is found across cultures. Furthermore, since the advent of the Convention on the Rights of the Child in 1989 (children here defined as under 18), almost every country in the world (except the U.S. and South Sudan) has legally committed to advancing an anti-discriminatory stance towards young people of all ages. This includes protecting children against unchecked child labor, enrollment in the military, prostitution, and pornography.
In many societies, those who reach a certain age (often 18, though this varies) are considered to have reached the age of majority and are legally regarded as adults who are responsible for their actions. People below this age are considered minors or children. A person below the age of majority may gain adult rights through [[Social:Emancipation of minors|legal emancipation]].

The [[Social:Legal working age|legal working age]] in Western countries is usually 14 to 16, depending on the number of hours and type of employment under consideration. Many countries also specify a minimum school leaving age, at which a person is legally allowed to leave [[Social:Compulsory education|compulsory education]]. This age varies greatly cross-culturally, spanning from 10 to 18, which further reflects the diverse ways formal education is viewed in cultures around the world.

In most democratic countries, a citizen is eligible to vote at age 18. In a minority of countries, the voting age is as low as 16 (for example, {{wipe|Brazil}}), and at one time was as high as 25 in Uzbekistan.

The age of consent to sexual activity varies widely between jurisdictions, ranging from 12 to 20 years, as does the [[Social:Marriageable age|age at which people are allowed to marry]].<ref name="ageofconsent">{{cite web |url=http://www.ageofconsent.com/ageofconsent.htm |title=Ageofconsent.com |publisher=Ageofconsent.com |accessdate=2012-09-15 |deadurl=yes |archiveurl=https://web.archive.org/web/20121023184559/http://www.ageofconsent.com/ageofconsent.htm |archivedate=2012-10-23 |df= }}</ref> Specific legal ages for adolescents that also vary by culture are enlisting in the military, gambling, and the purchase of alcohol, [[Engineering:Cigarette|cigarette]]s or items with parental advisory labels.
It should be noted that the legal coming of age often does not correspond with the sudden realization of autonomy; many adolescents who have legally reached adult age are still dependent on their guardians or peers for emotional and financial support. Nonetheless, new legal privileges converge with shifting social expectations to usher in a phase of heightened independence or social responsibility for most legal adolescents.

====Alcohol and illicit drug use====

=====Prevalence=====
Following a steady decline, beginning in the late 1990s up through the mid-2000s, illicit drug use among adolescents has been on the rise in the U.S.  Aside from alcohol, marijuana is the most commonly indulged drug habit during adolescent years. Data collected by the [[Organization:National Institute on Drug Abuse|National Institute on Drug Abuse]] shows that between the years of 2007 and 2011, marijuana use grew from 5.7% to 7.2% among 8th grade students; among 10th grade students, from 14.2% to 17.6%; and among 12th graders, from 18.8% to 22.6%.<ref name="NIDA">[http://www.drugabuse.gov/publications/drugfacts/high-school-youth-trends], National Institute of Drug Abuse. (2012, July). "Drugfacts: High school and youth."</ref>  Additional, recent years have seen a surge in popularity of [[Chemistry:MDMA|MDMA]]; between 2010 and 2011, the use of MDMA increased from 1.4% to 2.3% among high school seniors.<ref name="NIDA" /> The heightened usage of ecstasy most likely ties in at least to some degree with the rising popularity of rave culture.

One significant contribution to the increase in teenage substance abuse is an increase in the availability of [[Medicine:Prescription drug|prescription medication]]. With an increase in the diagnosis of behavioral and attentional disorders for students, taking pharmaceutical drugs such as Vicodin and Adderall for pleasure has become a prevalent activity among adolescents: 15.2% of high school seniors report having abused prescription drugs within the past year.<ref name="NIDA" />

Teenage alcohol drug use is currently at an all-time low.  Out of a polled body of students, 4.4% of 8th graders reported having been on at least one occasion been drunk within the previous month; for 10th graders, the number was 13.7%, and for 12th graders, 25%.<ref name="NIDA" />  More drastically, cigarette smoking has become a far less prevalent activity among American middle- and high-school students; in fact, a greater number of teens now smoke marijuana than smoke cigarettes, with one recent study showing a respective 15.2% versus 11.7% of surveyed students.<ref name="NIDA" />  Recent studies have shown that male late adolescents are far more likely to smoke cigarettes rather than females. The study indicated that there was a discernible gender difference in the prevalence of smoking among the students. The finding of the study show that more males than females began smoking when they were in primary and high schools whereas most females started smoking after high school.<ref>{{cite journal|last1=Mashamba|first1=Tshilidzi|last2=Mudhovozi|first2=Pilot|last3=Sodi|first3=Tholene|title=Gender differences in cigarette smoking among college students|journal=African Journal for Physical, Health Education, Recreation and Dance|date=September 2012|pages=117–130}}</ref> This may be attributed to recent changing social and political views towards marijuana; issues such as medicinal use and legalization have tended towards painting the drug in a more positive light than historically, while cigarettes continue to be vilified due to associated health risks.

Different drug habits often relate to one another in a highly significant manner. It has been demonstrated that adolescents who drink at least to some degree may be as much as sixteen times more likely than non-drinkers to experiment with illicit drugs.<ref name="Greenblatt">{{cite report |author=Greenblatt, Janet C. |authors= |date=2000 |title= Patterns of Alcohol Use Among Adolescents and Associations with Emotional and Behavioral Problems|url=http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.365.6700&rep=rep1&type=pdf |publisher=Office of Applied Studies, Substance Abuse and Mental Health Services Administration |page= |docket= |access-date=2018-06-29 |quote= }}</ref>

=====Social influence=====
[[File:Night Life in Cork, Ireland.jpg|thumb|Irish teenagers over 18 hanging around outside a bar. People under 18 are not allowed to drink outside the home; this is not strictly enforced in Ireland.]]
Peer acceptance and social norms gain a significantly greater hand in directing behavior at the onset of adolescence; as such, the alcohol and illegal drug habits of teens tend to be shaped largely by the substance use of friends and other classmates.  In fact, studies suggest that more significantly than actual drug norms, an individual's perception of the illicit drug use by friends and peers is highly associated with his or her own habits in substance use during both middle and high school, a relationship that increases in strength over time.<ref name="Duan et al">{{cite journal|last=Duan|first=L.|author2=Chou, C.|author3=Andreeva, V.|author4=Pentz, M.|title=Trajectories of Peer Social Influences as Long-term Predictors of Drug Use from Early Through Late Adolescence|journal=Journal of Youth and Adolescence|date=July 2009|volume=38|issue=3|pages=454–465|doi=10.1007/s10964-008-9310-y}}</ref>  Whereas social influences on alcohol use and marijuana use tend to work directly in the short term, peer and friend norms on smoking cigarettes in middle school have a profound effect on one's own likelihood to smoke cigarettes well into high school.<ref name="Duan et al" />  Perhaps the strong correlation between peer influence in middle school and cigarette smoking in high school may be explained by the addictive nature of cigarettes, which could lead many students to continue their smoking habits from middle school into late adolescence.

=====Demographic factors=====
Until mid-to-late adolescence, boys and girls show relatively little difference in drinking motives.<ref name="Kuntsche et al">{{cite journal|last=Kuntsche|first=E.|author2=Knibbe, R.|author3=Gmel, G.|author4=Engels, R.|title=Who drinks and why? A review of socio-demographic, personality, and contextual issues behind the drinking motives in young people|journal=Addictive Behaviors|year=2006|volume=31|issue=10|pages=1844–1857|doi=10.1016/j.addbeh.2005.12.028}}</ref>  Distinctions between the reasons for alcohol consumption of males and females begin to emerge around ages 14–15; overall, boys tend to view drinking in a more social light than girls, who report on average a more frequent use of alcohol as a coping mechanism.<ref name="Kuntsche et al" /> The latter effect appears to shift in late adolescence and onset of early adulthood (20–21 years of age); however, despite this trend, age tends to bring a greater desire to drink for pleasure rather than coping in both boys and girls.<ref name="Kuntsche et al" />

Drinking habits and the motives behind them often reflect certain aspects of an individual's personality; in fact, four dimensions of the Five-Factor Model of personality demonstrate associations with drinking motives (all but 'Openness').  Greater enhancement motives for alcohol consumption tend to reflect high levels of extraversion and sensation-seeking in individuals; such enjoyment motivation often also indicates low conscientiousness, manifesting in lowered inhibition and a greater tendency towards aggression.  On the other hand, drinking to cope with negative emotional states correlates strongly with high neuroticism and low agreeableness.<ref name="Kuntsche et al" />  Alcohol use as a negative emotion control mechanism often links with many other behavioral and emotional impairments, such as anxiety, depression, and low self-esteem.<ref name="Kuntsche et al" />

Research has generally shown striking uniformity across different cultures in the motives behind teen alcohol use. Social engagement and personal enjoyment appear to play a fairly universal role in adolescents' decision to drink throughout separate cultural contexts.  Surveys conducted in Argentina, Hong Kong, and Canada have each indicated the most common reason for drinking among adolescents to relate to pleasure and recreation; 80% of Argentinian teens reported drinking for enjoyment, while only 7% drank to improve a bad mood.<ref name="Kuntsche et al" />  The most prevalent answers among Canadian adolescents were to "get in a party mood," 18%; "because I enjoy it," 16%; and "to get drunk," 10%.<ref name="Kuntsche et al" />  In Hong Kong, female participants most frequently reported drinking for social enjoyment, while males most frequently reported drinking to feel the effects of alcohol.<ref name="Kuntsche et al" />

===Media===

====Body image====
[[File:Teenage girl texting.jpg|160px|thumb|Teenage girl texting]]
Much research has been conducted on the psychological ramifications of [[Philosophy:Body image|body image]] on adolescents. Modern day teenagers are exposed to more media on a daily basis than any generation before them. Recent studies have indicated that the average teenager watches roughly 1500 hours of television per year.<ref name="test">[http://www.csun.edu/science/health/docs/tv&health.html], TV-Free America. (2007). Television and Health. In ''The Sourcebook for Teaching Science.'' Retrieved 2012, from http://www.csun.edu/science/health/docs/tv&health.html.</ref> As such, modern day adolescents are exposed to many representations of ideal, societal beauty. The concept of a person being unhappy with their own image or appearance has been defined as "body dissatisfaction". In teenagers, body dissatisfaction is often associated with body mass, low [[Philosophy:Self-esteem|self-esteem]], and atypical eating patterns.<ref name="Makinen">{{cite journal | last1 = Mäkinen | first1 = M | display-authors = 1 | last2 = et al | year = 2012 | title = Body dissatisfaction and body mass in girls and boys transitioning from early to mid-adolescence: additional role of self-esteem and eating habits | url = | journal = BMC Psychiatry | volume = 12 | issue = | page = 35 | doi=10.1186/1471-244x-12-35}}</ref> Scholars continue to debate the effects of media on body dissatisfaction in teens.<ref name="Ata">{{cite journal | last1 = Ata | first1 = R. N. | last2 = Ludden | first2 = A. | last3 = Lally | first3 = M. M. | year = 2007 | title = The effects of gender and family, friends, peers, and media influences on eating behaviors and body image during adolescence | url = | journal = Journal of Youth and Adolescence | volume = 36 | issue = 8| pages = 1024–1037 | doi = 10.1007/s10964-006-9159-x }}</ref><ref name="Review of General Psychology">{{cite journal | last1 = Ferguson | first1 = C. J. | last2 = Winegard | first2 = B. | last3 = Winegard | first3 = B. | year = 2011 | title = Who is the fairest one of all? How evolution guides peer and media influences on female body dissatisfaction | url = http://www.tamiu.edu/~cferguson/Who%20Is%20the%20Fairest.pdf | format = PDF | journal = Review of General Psychology | volume = 15 | issue = 1 | pages = 11–28 | doi = 10.1037/a0022607 | deadurl = yes | archiveurl = https://www.webcitation.org/65q5xHqLw?url=http://www.tamiu.edu/~cferguson/Who%20Is%20the%20Fairest.pdf | archivedate = 2012-03-01 | df =  }}</ref>

====Media profusion====

Because exposure to media has increased over the past decade, adolescents' utilization of computers, cell phones, stereos and televisions to gain access to various mediums of [[Social:Popular culture|popular culture]] has also increased. Almost all American households have at least one television, more than three-quarters of all adolescents' homes have access to the Internet, and more than 90% of American adolescents use the Internet at least occasionally.<ref>{{cite journal|last=Lenhart|first=Amanda|title=Teens and social media|journal=Pew Internet and American Life Project|year=2007}}</ref>  As a result of the amount of time adolescents spend using these devices, their total media exposure is high. In the last decade, the amount of time that adolescents spend on the computer has greatly increased.<ref>{{cite journal|last=Greene|first=M|title=Trajectories of perceived adult and peer discrimination among Black, Latino, and Asian American adolescents: patterns and psychological correlates.|journal=Developmental Psychology|date=March 2006|volume=42|pages=391–396|pmid=16569162|doi=10.1037/0012-1649.42.2.218|issue=2}}</ref> Online activities with the highest rates of use among adolescents are video games (78% of adolescents), email (73%), instant messaging (68%), social networking sites (65%), news sources (63%), music (59%), and videos (57%).

====Social networking====

In the 2000s, social networking sites proliferated and a high proportion of adolescents used them: as of 2012 73% of 12–17 year olds reported having at least one social networking profile;<ref>{{cite journal|last=Reich|first=Stephanie M.|author2=Kaveri Subrahmanyam |author3=Guadalupe Espinoza|title=Friending, IMing, and Hanging Out Face-to-Face: Overlap in Adolescents' Online and Offline Social Networks|journal=Developmental Psychology|date=March 2012|volume=48|issue=2|pages=356–368|doi=10.1037/a0026980|pmid=22369341}}</ref> two-thirds (68%) of teens texted every day, half (51%) visited social networking sites daily, and 11% sent or received tweets at least once every day. More than a third (34%) of teens visited their main social networking site several times a day. One in four (23%) teens were "heavy" social media users, meaning they used at least two different types of social media each and every day.<ref>{{cite web|title=Teens are avid, daily users of social media|url=http://www.commonsensemedia.org/research/social-media-social-life/key-finding-1%3A-teens-are-avid,-daily-users-of-social-media|work=Social Media, Social Life: How Teens View Their Digital Lives|publisher=Common Sense Media|accessdate=6 December 2012}}</ref>

Although research has been inconclusive, some findings have indicated that electronic communication negatively affects adolescents' social development, replaces face-to-face communication, impairs their social skills, and can sometimes lead to unsafe interaction with strangers. A 2015 review reported that "adolescents lack awareness of strategies to cope with cyberbullying, which has been consistently associated with an increased likelihood of depression."<ref>{{cite journal|last1=Hamm|first1=MP|last2=Newton|first2=AS|last3=Chisholm|first3=A|last4=Shulhan|first4=J|last5=Milne|first5=A|last6=Sundar|first6=P|last7=Ennis|first7=H|last8=Scott|first8=SD|last9=Hartling|first9=L|title=Prevalence and Effect of Cyberbullying on Children and Young People: A Scoping Review of Social Media Studies|journal=JAMA Pediatrics|date=22 June 2015|pmid=26098362|doi=10.1001/jamapediatrics.2015.0944|volume=169|issue=8|pages=770–7}}</ref> Studies have shown differences in the ways the internet negatively impacts the adolescents' social functioning. Online socializing tends to make girls particularly vulnerable, while socializing in Internet cafés seems only to affect boys academic achievement. However, other research suggests that Internet communication brings friends closer and is beneficial for [[Medicine:Social anxiety|socially anxious]] teens, who find it easier to interact socially online.<ref>{{cite journal|last=Chen|first=Su-Yen|author2=Fu, Yang-Chih|title=Internet use and academic achievement in early adolescence|journal=Adolescence|year=2009|volume=44|issue=176|pages=797–812|url=http://web.ebscohost.com/ehost/detail?vid=6&hid=107&sid=fa31d0ca-f7e6-4ad5-b0e8-a5030d690614%40sessionmgr115&bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=sih&AN=47715864|accessdate=4 October 2012|pmid=20432601}}</ref> The more conclusive finding has been that Internet use has a negative effect on the physical health of adolescents, as time spent using the Internet replaces time doing physical activities. However, the Internet can be significantly useful in educating teens because of the access they have to information on many various topics.

===Transitions into adulthood===
{{see|Leaving the nest}}
[[File:Da Nang, Vietnam. A young Marine private waits on the beach during the Marine landing. - NARA - 532432 (restored).jpg|thumbnail|160px|A young U.S. Marine in the Vietnam War, 1965]]
A broad way of defining adolescence is the transition from child-to-adulthood. According to Hogan & Astone (1986), this transition can include markers such as leaving school, starting a full-time job, leaving the home of origin, getting married, and becoming a parent for the first time.<ref>Shanahan, N. (2000). "Pathways To Adulthood In Changing Societies: Variabilities and Mechanisms in Life Course Perspective"Annu. Rev. Sociol. 2000.</ref> However, the time frame of this transition varies drastically by culture. In some countries, such as the United States, adolescence can last nearly a decade, but in others, the transition—often in the form of a ceremony—can last for only a few days.<ref>Steinberg, L. (2011). "Adolescence", 9th ed. 101. New York, NY: McGraw-Hill.</ref>

Some examples of social and religious transition ceremonies that can be found in the U.S., as well as in other cultures around the world, are [[Religion:Confirmation|Confirmation]], Bar and Bat Mitzvahs, Quinceañeras, sweet sixteens, cotillions, and débutante balls. In other countries, initiation ceremonies play an important role, marking the transition into adulthood or the entrance into adolescence. This transition may be accompanied by obvious physical changes, which can vary from a change in clothing to tattoos and scarification.<ref name="ReferenceB"/> Furthermore, transitions into adulthood may also vary by gender, and specific rituals may be more common for males or for females. This illuminates the extent to which adolescence is, at least in part, a social construction; it takes shape differently depending on the cultural context, and may be enforced more by cultural practices or transitions than by universal chemical or biological physical changes.

==Promoting positive changes in adolescents==
At the decision-making point of their lives, youth is susceptible to drug addiction, sexual abuse, peer pressure, violent crimes and other illegal activities. Developmental Intervention Science (DIS) is a fusion of the literature of both developmental and intervention sciences. This association conducts youth interventions that mutually assist both the needs of the community as well as psychologically stranded youth by focusing on risky and inappropriate behaviors while promoting positive self-development along with self-esteem among adolescents.<ref>"The initiative to promote positive changes in youth". The Hindustan Times (New Delhi). 19th April, 2008.</ref>

==Criticism==
The concept of adolescence has been criticized by experts, such as Robert Epstein, who state that an undeveloped brain is not the main cause of teenagers' turmoils.<ref>{{cite web|url=http://drrobertepstein.com/pdf/Epstein-THE_MYTH_OF_THE_TEEN_BRAIN-Scientific_American_Mind-4-07.pdf|title=Dr. Robert Epstein: The myth of the teen brain - Psychology Today|publisher=}}</ref><ref>{{Cite news|url=https://theconversation.com/why-its-time-to-lay-the-stereotype-of-the-teen-brain-to-rest-85888|title=Why it's time to lay the stereotype of the 'teen brain' to rest|last=Romer|first=Dan|work=The Conversation|access-date=2017-11-21|language=en}}</ref> Some have criticized the concept of adolescence because it is a relatively recent phenomenon in human history created by modern society,<ref>{{cite web|url=https://www.psychologytoday.com/articles/199501/the-invention-adolescence|title=The Invention of Adolescence|magazine=Psychology Today|date=June 9, 2016|accessdate=February 19, 2017}}</ref><ref>{{cite journal|url=https://eric.ed.gov/?id=EJ482132|title=On the "Invention" of Adolescence.|last=Fasick|first=Frank A.|journal=Journal of Early Adolescence|volume=14|number=1|pages=6–23|date=February 1994|doi=10.1177/0272431694014001002}} "[...] the application of technology to increase productivity, the affluence generated by it, and the related structural changes in society have contributed to the creation of adolescence in the North American urban-industrial society."</ref><ref>{{cite book|url=https://books.google.com/books/about/Teen_2_0.html?id=OENf1J45SS0C|title=Teen 2.0: Saving Our Children and Families from the Torment of Adolescence|last=Epstein|first=Robert|publisher=Linden Publishing|date=2010|isbn=1610351010}}</ref><ref>{{cite journal|last1=Demos|first1=John|last2=Demos|first2=Virginia|date=1969|title=Adolescence in Historical Perspective|url=|journal=Journal of Marriage and Family|volume=31|pages=632–638|doi=10.2307/349302|jstor=349302|via=|number=4}} "The idea of adolescence is today one of our most widely held and deeply imbedded assumptions about the process of human development. Indeed most of us treat it not as an idea but as a ''fact''. [...] The concept of adolescence, as generally understood and applied, did not exist before the last two decades of the nineteenth century."</ref> and have been highly critical of what they view as the [[Social:Infantilization|infantilization]] of young adults in American society.<ref>{{cite web|url=http://help.fortroubledteens.com/the-danger-of-treating-teens-like-children.html|title=The Danger of Treating Teens Like Children|website=help.fortroubledteens.com}}</ref> In an article for ''Scientific American'', Robert Epstein and Jennifer Ong state that "American-style teen turmoil is absent in more than 100 cultures around the world, suggesting that such mayhem is not biologically inevitable. Second, the brain itself changes in response to experiences, raising the question of whether adolescent brain characteristics are the cause of teen tumult or rather the result of lifestyle and experiences."<ref>{{cite magazine|url=https://www.scientificamerican.com/article/are-teens-who-behave-reck/|title=Are the Brains of Reckless Teens More Mature Than Those of Their Prudent Peers?|author1-last=Epstein|author1-first=Robert|author2-last=Ong|author2-first=Jennifer|magazine=Scientific American|date=August 25, 2009|accessdate=October 5, 2017}}</ref> David Moshman has also stated in regards to adolescence that brain research "is crucial for a full picture, but it [[Correlation does not imply causation|does not provide an ultimate explanation]]."<ref>{{Cite web|url=https://www.huffingtonpost.com/david-moshman/adolescents-and-their-tee_b_858360.html|title=The Teenage Brain: Debunking the 5 Biggest Myths|last=Moshman|first=David|date=2011-05-17|website=Huffington Post|language=en-US|access-date=2017-11-20}}</ref>

Other critics of the concept of adolescence do point at individual differences in brain growth rate, citing that some (though not all) early teens still have infantile undeveloped [[Biology:Corpus callosum|corpus callosum]]s, concluding that "the adult in *every* adolescent" is too generalizing. These people tend to support the notion that a more interconnected [[Biology:Brain|brain]] makes more precise distinctions (citing [[Biography:Ivan Pavlov|Pavlov]]'s comparisons of conditioned reflexes in different species) and that there is a [[Critical phenomena|non-arbitrary threshold]] at which distinctions become sufficiently precise to correct assumptions afterward as opposed to being ultimately dependent on exterior assumptions for communication. They argue that this threshold is the one at which an individual is objectively capable of speaking for himself or herself, as opposed to culturally arbitrary measures of "maturity" which often treat this ability as a sign of "immaturity" merely because it leads to questioning of authorities. These people also stress the low probability of the threshold being reached at a birthday, and instead advocate non-chronological emancipation at the threshold of afterward correction of assumptions.<ref>{{Cite journal|last=Paul|first=Richard W.|date=1988|title=Ethics without Indoctrination.|url=https://eric.ed.gov/?id=EJ373375|journal=Educational Leadership|language=en|volume=45|issue=8|pages=10–19|via=}}</ref> They sometimes cite similarities between "adolescent" behavior and KZ syndrome (inmate behavior in adults in prison camps) such as aggression being explainable by oppression and "immature" financial or other risk behavior being explainable by a way out of captivity being more worth to captive people than any incremental improvement in captivity, and argue that this theory successfully predicted remaining "immature" behavior after reaching the age of majority by means of longer-term traumatization. In this context, they refer to the fallibility of official assumptions about what is good or bad for an individual, concluding that [[Philosophy:Paternalism|paternalistic]] "rights" may harm the individual. They also argue that since it never took many years to move from one group to another to avoid inbreeding in the [[Earth:Paleolithic|paleolithic]], [[Philosophy:Evolutionary psychology|evolutionary psychology]] is unable to account for a long period of "immature" risk behavior.<ref>{{Cite book|url=https://www.worldcat.org/oclc/51633820|title=The Thinker's Guide to Ethical Reasoning|last=Paul|first=Richard W.|last2=Elder|first2=Linda|publisher=Foundation for Critical Thinking|others=|year=2013|isbn=0944583172|edition=2nd|location=Dillon Beach, CA|pages=|oclc=51633820}}</ref>

==See also==
* [[Medicine:Adolescent medicine|Adolescent medicine]]
* Children and adolescents in the United States
* Clique
* Emerging adulthood and early adulthood
* Ephebophilia – a sexual preference in which an adult is primarily or exclusively sexually attracted to mid to late adolescents
* Fear of youth
* [[Social:Relational aggression|Relational aggression]]
* [[Social:Student voice|Student voice]]
* [[Social:Suitable age and discretion|Suitable age and discretion]]
* Timeline of young people's rights in the United Kingdom
* Timeline of young people's rights in the United States
* Young adult (psychology)
* [[Social:Youth|Youth]]
* [[Social:Youth culture|Youth culture]]
* Young worker safety and health

==References==
{{Reflist|30em}}

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{{s-bef|before=Preadolescence}}
{{s-ttl|title=Stages of human development|years='''Adolescence'''}}
{{s-aft|after=Young adult}}
{{S-end}}
{{Humandevelopment}}
{{Subject bar|commons=yes|commons-search=Category:Adolescence|wikt=yes|b=yes|q=yes|q-search=Teenagers|s=yes|d=Q131774}}

[[Category:Educational psychology]]

{{Sourceattribution|Adolescence|1}}