11.3 Adolescence: Minding the Gap

Between childhood and adulthood is an extended developmental stage that may not qualify for a “hood” of its own, but that is clearly distinct from the stages that come before and after. Adolescence is the period of development that begins with the onset of sexual maturity (about 11 to 14 years of age) and lasts until the beginning of adulthood (about 18 to 21 years of age). Unlike the transition from embryo to fetus or from infant to child, this transition is sudden and clearly marked. In just 3 or 4 years, the average adolescent gains about 40 pounds and grows about 10 inches. For girls, all this growing starts at about the age of 10 and ends when they reach their full heights at about the age of 15.5. For boys it starts at about the age of 12 and ends at about the age of 17.5.

Adolescents are often described as gawky because different parts of their faces and bodies mature at different rates. But as musician Justin Timberlake can attest, the gawkiness generally clears up.

SETH POPPEL/YEARBOOKL IBRARY
KEVIN MAZUR/WIREIM AGE/GETTY IMAGES

The beginnings of this growth spurt signals the onset of puberty, which refers to the bodily changes associated with sexual maturity. These changes involve primary sex characteristics, which are bodily structures that are directly involved in reproduction, for example, the onset of menstruation in girls and the enlargement of the testes, scrotum, and penis and the emergence of the capacity for ejaculation in boys. They also involve secondary sex characteristics, which are bodily structures that change dramatically with sexual maturity but that are not directly involved in reproduction, for example, the enlargement of the breasts and the widening of the hips in girls and the appearance of facial hair, pubic hair, underarm hair, and the lowering of the voice in both genders. This pattern of changes is caused by increased production of estrogen in girls and testosterone in boys.

Just as the body changes during adolescence, so too does the brain. For example, there is a marked increase in the growth rate of tissue connecting different regions of the brain just before puberty (Thompson et al., 2000). Between the ages of 6 and 13, the connections between the temporal lobe (the brain region specialized for language) and the parietal lobe (the brain region specialized for understanding spatial relations) multiply rapidly and then stop—just about the time that the critical period for learning a language ends (see FIGURE 11.11).

Figure 11.11: Your Brain on Puberty The development of neurons peaks in the frontal and parietal lobes at about age 12 (a, b), in the temporal lobe at about age 16 (c), and continues to increase in the occipital lobe through age 20 (d).

But the most important neural changes occur in the prefrontal cortex. An infant’s brain forms many more new synapses than it actually needs, and by the time children are 2 years old they have about 15,000 synapses per neuron, which is roughly twice as many as the average adult (Huttenlocher, 1979). This early period of synaptic proliferation is followed by a period of synaptic pruning in which the connections that are not frequently used are eliminated. This is a clever system that allows the brain’s wiring to be determined in part by its experience in the world. Scientists used to think that this process ended early in life, but recent evidence suggests that the prefrontal cortex undergoes a second wave of synaptic proliferation just before puberty, and a second round of synaptic pruning during adolescence (Giedd et al., 1999). Clearly, the adolescent brain is a work in progress.

The Protraction of Adolescence

The age at which puberty begins varies across individuals (e.g., people tend to reach puberty at about the same age as their same-sexed parent did) and across cultures (e.g., African American girls tend to reach puberty before European American girls do). It also varies across generations (Malina, Bouchard, & Beunen, 1988). For example, in Scandinavia, the United Kingdom, and the United States, the age of first menstruation was between 16 and 17 years in the 19th century but was approximately 13 years in 1960. A more recent study found that the average age of breast development for Danish girls has decreased by an entire year since 1992 alone (Aksglaede et al., 2009). The average age at which American boys begin puberty has now fallen to between 9 and10 years old (Herman-Giddens et al., 2012). Why so much earlier now than just a few decades ago? Puberty is accelerated by body fat (Kim & Smith, 1998), and the decrease in the age of the onset is largely due to improved diet and health (Ellis & Garber, 2000). But puberty in girls can also be hastened by exposure to environmental toxins that mimic estrogen (Buck Louis et al., 2008) or by stressful family situations (Belsky, 2012).

The increasingly early onset of puberty has important psychological consequences. Just two centuries ago, the gap between childhood and adulthood was relatively brief because people became physically mature at roughly the same time that they were ready to accept adult roles in society, and these roles did not normally require them to have extensive schooling. But in modern societies, people typically spend 3 to 10 years in school after they reach puberty. Thus, while the age at which people become physically adult has decreased, the age at which they are prepared or allowed to take on adult responsibilities has increased, and so the period between childhood and adulthood has become protracted. What are the consequences of a protracted adolescence?

About 60% of preindustrial societies don’t even have a word for adolescence (Schlegel & Barry, 1991). When a Krobo female menstruates for the first time, older women take her into seclusion for 2 weeks and teach her about sex, birth control, and marriage. Afterward, a public ceremony called the durbar is held, and the young female who that morning was regarded as a child is thereafter regarded as an adult.

©ROBERT BURCH PHOTOGRAPHY

Adolescence is often characterized as a time of internal turmoil and external recklessness, and some psychologists have speculated that the protraction of adolescence is in part to blame for its sorry reputation (Moffitt, 1993). According to these theorists, adolescents are adults who have temporarily been denied a place in adult society. American teenagers are subjected to 10 times as many restrictions as older adults, and twice as many restrictions as active-duty U.S. Marines or incarcerated felons (Epstein, 2007a). As such, they feel especially compelled to do things to protest these restrictions and demonstrate their adulthood, such as smoking, drinking, using drugs, having sex, and committing crimes. In a sense, adolescents are people who are forced to live in a strange gap between two worlds, and the pathologies of adolescence are partly a result of this predicament. As one researcher noted, sult of this predicament. As one researcher noted, “Trapped in the frivolous world of peer culture, they learn virtually everything they know from one another rather than from the people they are about to become. Isolated from adults and wrongly treated like children, it is no wonder that some teens behave, by adult standards, recklessly or irresponsibly” (Epstein, 2007b).

But the storm and stress of adolescence is neither as prevalent nor as inevitable as HBO would have us believe (Steinberg & Morris, 2001). Research suggests that the “moody adolescent” who is a victim of “raging hormones” is largely a myth. Adolescents are no moodier than children (Buchanan, Eccles, & Becker, 1992), and fluctuations in their hormone levels have only a tiny impact on their moods (Brooks-Gunn, Graber, & Paikoff, 1994). Although they can be more impulsive and susceptible to peer influence than adults (see FIGURE 11.12), they are just as capable of making wise decisions based on good information (Steinberg, 2007). It is true that the majority of adolescents dabble in misbehavior, but don’t actually major in it. For example, most adolescents in the United States get drunk at least once before they graduate from high school, but few develop drinking problems or allow alcohol to impair their academic success or personal relationships (Hughs, Power, & Francis, 1992; Johnston, Bachman, & O’Malley, 1997). Most adolescent experiments have no long-term consequences, and the vast majority of adolescents who try drugs or break the law end up becoming sober, law-abiding adults (Steinberg, 1999). In short, the hijinks of adolescence are typically minor and temporary, and in some cultures they barely occur at all (Epstein, 2007b). Adolescence is not a terribly troubled time for most people, and most adolescents “age out” of any troubles they get themselves into (Sampson & Laub, 1995).

Figure 11.12: How Do Peers Affect Decision Making? Adolescents make better decisions when no one is around! Participants in one study played a video driving game with or without their peers in the room. The presence of peers greatly increased the number of risks taken and crashes experienced by adolescents, but had little or no effect on adults (Gardner & Steinberg, 2005).

These students at the University of Missouri (left) may be experimenting with reckless behavior, but they are unlikely to become reckless adults. Of course, the Vermont State Trooper (right) who is inspecting the car in which four teens died after a night of drinking would probably like to remind them that this rule only applies to those who live.

AP PHOTO/L.G. PATTERSON
AP PHOTO/ALDEN PELLETT

Sexuality

Figure 11.13: Early Puberty Early puberty is a source of psychological distress for women (Ge, Conger, & Elder, 1996).

Puberty can be a difficult time, but it is especially difficult for girls who reach it earlier than their peers. These girls are more likely to experience a range of negative consequences, from distress and depression to delinquency and disease (Mendle, Turkheimer, & Emery, 2007; see FIGURE 11.13). This happens for several reasons (Ge & Natsuaki, 2009). First, early bloomers don’t have as much time as their peers do to develop the skills necessary to cope with adolescence (Petersen & Grockett, 1985), but because they look so mature, people expect them to act like adults. In other words, early puberty creates unrealistic expectations and demands that the adolescent may have trouble fulfilling. Second, early blooming girls draw the attention of older men, who may lead them into a variety of unhealthy activities (Ge, Conger, & Elder, 1996). Some research suggests that for girls, the timing of puberty has a greater influence on emotional and behavioral problems than does the occurrence of puberty itself (Buchanan et al., 1992). The timing of puberty does not have such consistent effects on boys: some studies suggest that early maturing boys do better than their peers, some show they do worse, and some show that there is no difference at all (Ge, Conger, & Elder, 2001). Interestingly, recent research suggests that for boys, tempo, the speed with which they transition from the first to the last stages of puberty, may be a better predictor of negative outcomes than is timing (Mendle et al., 2010).

Figure 11.14: Polling Trends Americans’ attitudes about homosexuality have changed dramatically in the last few years, as witnessed by their rapidly changing views on same-sex marriage.

GRAPH FROM SILVER (2013).

For some adolescents, puberty is additionally complicated by the fact that they are attracted to members of the same sex. Most gay men report having become aware of their sexual orientation between the ages of 6 and 18, and most gay women report having become aware between the ages of 11 and 26 (Calzo et al., 2011). Not only does their sexual orientation make gay adolescents different from the vast majority of their peers (a mere 3.5% of American adults identify themselves as lesbian, gay, or bisexual; Gates, 2011), but it can also subject them to disapproval from family, friends, and community. Americans are rapidly becoming more accepting of homosexuality (see FIGURE 11.14), but there are still plenty who disapprove. And in some nations, people do more than disapprove: They send gay citizens to prison or sentence them to death.

Jane Clementi’s 18-year-old son Tyler committed suicide in 2010 after a college roommate videotaped him kissing another man. She later said, “I think some people think that sexual orientation can be changed or prayed over. But I know sexual orientation is not up for negotiation. I don’t think my children need to be changed. I think that what needed changing is attitudes, or myself, or maybe some other people I know” (quoted in Zernike, 2012).

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What determines whether a person’s sexuality is primarily oriented toward the same or the opposite sex? For a long time, psychologists believed that a person’s sexual orientation depended primarily on his or her upbringing. For example, psychoanalytic theorists claimed that boys who grow up with a domineering mother and a submissive father are less likely to identify with their father and are therefore more likely to become homosexual. Okay. Nice theory. But the fact is that scientific research has failed to identify any aspect of parenting that has a significant impact on a child’s ultimate sexual orientation (Bell, Weinberg, & Hammersmith, 1981). Perhaps the most telling fact is that children raised by homosexual couples and children raised by heterosexual couples are equally likely to become heterosexual adults (Patterson, 1995). There is also little support for the idea that a person’s early sexual encounters have a lasting impact on his or her sexual orientation (Bohan, 1996).

So what does determine a person’s sexual orientation? There is now considerable evidence to suggest that biology plays the major role. Not only do gay people have a larger proportion of gay siblings than do heterosexuals (Bailey et al., 1999), but the identical twin of a gay man (with whom he shares 100% of his genes) has a 50% chance of being gay, whereas the fraternal twin or nontwin brother of a gay man (with whom he shares 50% of his genes) has only a 15% chance (Bailey & Pillard, 1991; Gladue, 1994). A similar pattern has emerged in studies of women (Bailey et al., 1993). Some evidence suggests that the fetal environment may play a role in determining sexual orientation and that high levels of androgens in the womb may predispose a person—whether male or female—later to develop a sexual preference for women (Ellis & Ames, 1987; Meyer-Bahlberg et al., 1995). Perhaps this is why the brains of gay people tend to look like the brains of opposite-gendered straight people (Savic & Lindstrom, 2008). For example, the brain’s two hemispheres tend to be unequally sized among straight men and gay women (both of whom are attracted to women), but equally sized among straight women and gay men (both of whom are attracted to men).

The human papilloma virus is a sexually transmitted disease that can lead to cervical cancer. Luckily, there is a vaccine that can prevent it. Some parents worry that being vaccinated will encourage their daughters to have sex early, but studies show that young women who have been vaccinated do not have sex earlier than those who have not been vaccinated (Bednarczyk et al., 2012).

HORIZONS WWP/ALAMY

Of course, genes and prenatal biology cannot be the sole determinant of a person’s sexual orientation because many homosexual men and women have identical twins who shared both their fetal environment and their genes, and who are nonetheless heterosexual. There must be other factors and, at present, we just don’t know what they are. But one thing we do know is that regardless of what leads people to have a particular sexual orientation, there is no evidence that it can be changed by so-called conversion therapy (American Psychological Association, 2009). It is also worth noting that about 1% of people claim to have no sexual orientation of any kind and have never experienced sexual attraction to either gender (Bogaert, 2004). The science of sexual orientation is still young and fraught with conflicting findings, but one thing that seems abundantly clear is that sexual orientation is not simply a matter of choice.

But sexual behavior is a matter of choice, and many American teenagers choose it. Although the percentage of American teenagers who have had sex has been steadily declining (see FIGURE 11.15), it is still more than a third. The problem with this is that teenagers’ interest in sex typically surpasses their knowledge about it. Most American parents never talk in great depth with their children about sex (Ansuini, Fiddler-Woite, & Woite, 1996), and those who do tend to start late because they overestimate the age at which their children become sexually active (Jaccard, Dittus, & Gordon, 1998; see FIGURE 11.16). Ignorance has consequences. A quarter of American teenagers have had four or more sexual partners by their senior year in high school, but only about half report using a condom during their last intercourse (Centers for Disease Control, 2002). Although teen birth rates have been falling in the United States for about 20 years, they are still the highest in the developed world, and consequently, so is the rate of abortion.

Figure 11.15: Teenage Sex The percentage of American teenagers who have had sex has been declining in recent years (Martinez et al., 2011).

Figure 11.16: What Parents Think about Teenage Sex When American parents talk to teens about sex, it is often too little and too late. Research shows that American teens have sex earlier than their parents think they do (Jaccard et al., 1998).

What can be done? Despite what some people say, the best scientific evidence suggests that sex education does not increase the likelihood that teenagers will have sex. Instead, sex education leads teens to delay having sex for the first time, increases the likelihood they will use birth control when they do have sex, and lowers the likelihood that they will get pregnant or catch a sexually transmitted disease (Mueller, Gavin, & Kulkarni, 2008; Satcher, 2001). Despite these documented benefits, sex education in American schools is often absent, sketchy, or based on the goal of abstinence rather than harm prevention. Alas, there is little evidence to suggest that abstinence-only programs are effective (Kohler, Manhart, & Lafferty, 2008), and some studies suggest that teens who take abstinence pledges are just as likely to have sex as those who don’t, but are less likely to use birth control (Rosenbaum, 2009). That’s too bad, because teenage mothers fare more poorly than teenage women without children on almost every measure of academic and economic achievement, and their children fare more poorly on most measures of educational success and emotional well-being than do the children of older mothers (Olausson et al., 2001).

Parents and Peers

“Who am I?” is a question asked by amnesiacs and adolescents, who tend to ask it for different reasons. Children’s views of themselves and their world are tightly tied to the views of their parents, but puberty creates a new set of needs that begins to snip away at those bonds by orienting adolescents toward peers rather than parents. Psychologist Erik Erikson (1959) characterized each stage of life by the major task confronting the individual at that stage. His stages of psychosocial development (shown in TABLE 11.2) suggest that the major task of adolescence is the development of an adult identity. Whereas children define themselves almost entirely in terms of their relationships with parents and siblings, adolescence marks a shift in emphasis from family relations to peer relations.

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Two things can make this shift difficult. First, children cannot choose their parents, but adolescents can choose their peers. As such, adolescents have the power to shape themselves by joining groups that will lead them to develop new values, attitudes, beliefs, and perspectives. In a sense, the adolescent has the opportunity to invent the adult he or she will soon become, and the responsibility this opportunity entails can be overwhelming. Second, as adolescents strive for greater autonomy, their parents naturally rebel. For instance, parents and adolescents tend to disagree about the age at which certain adult behaviors—such as staying out late or having sex—are permissible, and you don’t need a scientist to tell you which position each party in this conflict tends to hold (Holmbeck & O’Donnell, 1991). Because adolescents and parents often have different ideas about who should control the adolescent’s behavior, their relationships become more conflictive and less close, and their interactions become briefer and less frequent (Larson & Richards, 1991). Even so, adolescents and their parents have surprisingly few conflicts (Chung, Flook, & Fuligni, 2009), and when they do argue it tends to be over minor issues, such as dress and language (which may explain why teenagers argue more with their mothers, who are typically in charge of such issues, than with their fathers; Caspi et al., 1993).

Adolescents form same-sex cliques that meet opposite-sex cliques in public places. Eventually, these people will form mixed-sex cliques, pair off into romantic relationships, get married, have children, and then worry about them when they do all the same things.

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Adolescents pull away from their parents, but more importantly, they move toward their peers. Studies show that across a wide variety of cultures, historical epochs, and even species, peer relations evolve in a similar way (Dunphy, 1963; Weisfeld, 1999). Young adolescents initially form groups or “cliques” with same-sexed peers, many of whom were friends during childhood (Brown, Mory, & Kinney, 1994). Next, male cliques and female cliques begin to meet in public places, such as town squares or shopping malls, and they begin to interact—but only in groups and only in public. After a few years, the older members of these same-sex cliques peel off and form smaller, mixed-sex cliques, which may assemble in private as well as in public, but usually assemble as a group. Finally, couples (typically a male and a female) peel off from the small, mixed-sex clique and begin romantic relationships.

Studies show that throughout adolescence, people spend increasing amounts of time with opposite-sex peers while maintaining the amount of time they spend with same-sex peers (Richards et al., 1998), and they accomplish this by spending less time with their parents (Larson & Richards, 1991). Although peers exert considerable influence on the adolescent’s beliefs and behaviors, this influence generally occurs because adolescents respect, admire, and like their peers and not because their peers pressure them (Susman et al., 1994). In fact, as they age, adolescents show an increasing tendency to resist peer pressure (Steinberg & Monahan, 2007). Acceptance by peers is of tremendous importance to adolescents, and those who are rejected by their peers tend to be withdrawn, lonely, and depressed (Pope & Bierman, 1999). Fortunately for those of us who were seventh-grade nerds, individuals who are unpopular in early adolescence can become popular in later adolescence as their peers become less rigid and more tolerant (Kinney, 1993).