Chapter 9: Developmental Psych

refers to the years of rapid physical growth and sexual maturation that end childhood, producing a person of adult size, shape, and sexuality.

when does puberty Start?
This process normally starts between ages 8 and 14

The average age of menarche among normal-weight girls is
12 years, 8 months

A girl’s first menstrual period, signaling that she has begun ovulation. Pregnancy is biologically possible, but ovulation and menstruation are often irregular for years after menarche.

A boy’s first ejaculation of sperm. Erections can occur as early as infancy, but ejaculation signals sperm production. Spermarche may occur during sleep (in a “wet dream”) or via direct stimulation.

The typical age of spermarche is just
under 13 years, close to the age for menarche.

The process begins deep within the brain when biochemical signals from the

A gland in the brain that responds to a signal from the hypothalamus by producing many hormones, including those that regulate growth and that control other glands, among them the adrenal and sex glands

HPA (hypothalamus-pituitary-adrenal) axis:
sequence of hormone production that originates in the hypothalamus, moves to the pituitary, and then to the adrenal glands.

HPG (hypothalamus-pituitary-gonad) axis:
A sequence of hormone production that originates in the hypothalamus, moves to the pituitary, and then to the gonads.

n adolescence, gonadotropin-releasing hormone (GnRH) is released by the hypothalamus, causing the pituitary to release gonadotropins (LH & FSH), which in turn activate the gonads.
As a result, the gonads enlarge and increase their production of sex hormones, chiefly estradiol in girls and testosterone in boys.

adrenal glands produce both hormones in both sexes.
Estrogens (including estradiol) are female hormones and androgens (including testosterone) are male hormones,

peak fertility occurs four to six years later.

Hormonal increases affect
psychopathology in sex-specific ways

Psychological disorders in both sexes increase at
adolescence, but males are twice as likely as females to become schizophrenic, whereas females are twice as likely to become depressed.

circadian rhythm
A day-night cycle of biological activity that occurs approximately every 24 hours (circadian means “about a day”).

The hypothalamus and the pituitary regulate the hormones that affect the
biorhythms of stress, appetite, sleep, and so on

Hormones of the HPA axis at puberty cause a
phase delay in sleep-wake cycles, making many teens wide awake and hungry at midnight but half asleep with little appetite or energy all morning

Biology (circadian rhythms) and culture (parties and technology)
work to make teenagers increasingly sleep-deprived with each year of high school

Not only does insufficient sleep decrease learning and well-being, but so does an uneven sleep schedule (more sleep on weekends, erratic bedtimes)

Many high schools begin before 8 A.M., even though the evidence finds
that a later start time improves adolescent learning (

Sleepy teenagers are more likely to have many problems
hey doze in school (see Figure 9.2), fall asleep while driving, develop eating and mood disorders (depression, conduct disorder, anxiety), have poor relationships with their parents, and abuse substances (partly to wake up or to sleep), thereby jeopardizing their health

precocious puberty
(sexual development before age 8)

About two-thirds of the variation in age of puberty is

African Americans reach puberty about seven months earlier than European or Hispanic Americans, whereas Chinese Americans average several months later (

northern European girls reach menarche at
13 years, 4 months,

southern European girls do so at
12 years, 5 months

The female height spurt occurs before

the increase in height is relatively late, occurring after

when it comes to hormonal and sexual changes
girls are only a few months ahead of boys.

he sixth-grade boy with sexual fantasies about the taller girls in his class is neither perverted nor precocious;
his hormones are simply ahead of his visible growth.

Quite normal are increased hormones any time from ages 8 to 14, with the precise age affected by
genes, gender, body fat, and stress.

Heavy girls reach menarche years earlier than
malnourished ones do.

Most girls must weigh at least ______(45 kilograms) before they experience their first period
100 pounds

Worldwide, urban children are more often overfed and underexercised than rural children

Puberty has occurred at younger ages every century since then
his is one result of the secular trend: More food has allowed biological advances.

When did the secular trend stop?
the secular trend stopped at about 1990 in developed nations.

One hormone causes increased body fat and then triggers puberty

A hormone that affects appetite and is believed to affect the onset of puberty. Leptin levels increase during childhood and peak at around age 12

eptin levels in the blood show a natural increase over childhood,
peaking at puberty

leptin affects appetite in females more than it does in males
and body fat is more closely connected to the onset of puberty in girls than in boys.

U.S. boys who are heavy in childhood reach puberty later, not earlier, than others

Stress affects the sexual-reproductive system
making reproduction more difficult in adulthood and by hastening (not delaying) the hormonal onset of puberty

puberty arrives earlier if
a child’s parents are sick, addicted, or divorced, or if the neighborhood is violent and impoverished.

Early-maturing girls tend
to have lower self-esteem, more depression, and poorer body image than do other girls

early-maturing boys have been more
aggressive, law-breaking, and alcohol-abusing than later-maturing boys

For both sexes, early puberty correlates with
sexual activity and teenage parenthood, which lead to depression and other psychosocial problems

If puberty is both early and quick,
boys are especially likely to become depressed; in adolescence, male depression may appear as anger:

Boys who reach puberty late also have problems
becoming more anxious, depressed, and afraid of sex than are other boys

growth spurt
growth of the limbs precedes growth of the torso.

For instance, at age 17, the average girl has
twice the percentage of body fat as her male classmate, whose increased weight is mostly muscle

A height spurt follows the weight spurt.
hen, a year or two later, a muscle spurt occurs.

Lungs triple in weight
consequently, adolescents breathe more deeply and slowly.

The heart doubles in size and the heartbeat slows
decreasing the pulse rate while increasing blood pressure

Red blood cells increase in both sexes
but dramatically more so in boys, which aids oxygen transport during intense exercise

Endurance improves:
Some teenagers can run for miles or dance for hours.

Both weight and height increase
before muscles and internal organs

Injuries increase at puberty
partly because the height spurt precedes increases in bone mass, making young adolescents particularly vulnerable to fracture

Only one organ system, the lymphoid system
decreases in size;

mild asthma often disappears at

Although everyone’s hair changes texture at

primary sex characteristics:
he parts of the body that are directly involved in reproduction, including the vagina, uterus, ovaries, testicles, and penis.

secondary sex characteristics
Physical traits that are not directly involved in reproduction but that indicate sexual maturity, such as a man’s beard and a woman’s breasts.

Cohort and age are crucial factors

In 2011, only 15 percent of high school seniors ate the recommended three or more servings of vegetables a day

especially common after puberty.
Deficiencies of iron, calcium, zinc, and other minerals

menstruation depletes iron
anemia is more likely among adolescent girls than among people of any other age or gender

research in Saudi Arabia involving 18- to 23-year-old college women
found that, despite these advantages, half had insufficient iron, and many of them were clinically anemic

he cutoff for anemia is higher for boys than for girls
because males require more iron to be healthy

any adolescents of both sexes in every nation spurn iron-rich foods in favor
f iron-poor chips, sweets, and fries. Coffee, tea, and soda reduce iron absorption

daily recommended intake of calcium for teenagers is
1,300 milligrams, the average North American teen consumes fewer than 500 milligrams a day.

In 2011, only 15 percent of U.S. twelfth graders drank even three glasses of milk daily

In the twenty-first century, the beverage most often consumed by U.S. 2- to 18-year-olds is
soda with 11 percent of high school students drinking three or more glasses of soda each day

About half of adult bone mass is acquired from ages 10 to 20,
hich means many contemporary teenagers will develop osteoporosis (fragile bones) because of too little calcium and too much soda, day in and day out

One reason for poor nutrition among teenagers is
anxiety about body image

Boys want to look taller and stronger, a concern that increases from ages
12 to 17

In both sexes and in adolescents of all ethnicities,
dissatisfaction with body image correlates strongly with low self-esteem

Thus, as the hormones of puberty awaken sexual interest, both sexes become less happy with their own bodies and more superficial in what they admire in the other sex.
This is true worldwide.

In many nations, the ideal body type is tall and thin,And the ideal facial appearance is Anglo-Saxon.

Eating disorders are rare in childhood but increase dramatically at
puberty,accompanied by distorted body image, food obsession, and depression

ere we describe two other eating disorders that are common in adolescence and early adulthood.

about 1 percent of all women in late adolescence suffer from anorexia it leads to death by organ failure or suicide for between 5 and 20 percent of sufferers. nervosa,

anorexia nervosa
An eating disorder characterized by self-starvation. Affected individuals voluntarily undereat and often overexercise, depriving their vital organs of nutrition. Anorexia can be fatal.

If someone’s body mass index (BMI) is
18 or lower, or if she (or, less often, he) loses more than 10 percent of body weight within a month or two, anorexia is suspected.

Anorexia is officially diagnosed when four symptoms are evident:
Refusal to maintain a weight that is at least 85 percent of normal BMI

Intense fear of weight gain

Disturbed body perception and denial of the problem

Absence of menstruation (in adolescent and adult females)

Certain alleles increase the risk of anorexia
but context is crucial. The disorder seems related to cultural pressure to be thin.

bulimia nervosa:(binge-purge syndrome) about three times as common as anorexia
n eating disorder characterized by binge eating and subsequent purging, usually by induced vomiting and/or use of laxatives.

BULIMIA: Most are close to normal in weight and therefore unlikely to starve.
However, they risk serious health problems, including damage to their gastrointestinal systems and cardiac arrest from electrolyte imbalance (Shannon, 2007). They also risk compulsive disorders and depression, including thoughts of suicide

According to DSM-IV,
1 to 3 percent of female teenagers and young adults in the United States are clinically bulimic.

Binging and purging at least once a week for three months

Uncontrollable urges to overeat

A distorted perception of body size

Many experts think that eating disorders are much more widespread than DSM statistics portray
17 percent of the girls had eaten nothing for at least one 24-hour period in the past month, as had 7 percent of the boys

where intense fear and excitement originate

Which matures first?
amygdala matures before the prefrontal cortex: the instinctual and emotional areas of the adolescent brain develop ahead of the reflective

whereas the cortex responds more to age and experience than to hormones.
pubertal hormones target the amygdala directly

Emotional control is not fully developed until

When compared with 18- to 23-year-olds,
14- to 15-year-olds show heightened arousal in the brain’s reward centers, making them seek excitement and pleasure

teenage brains have underdeveloped “response inhibition, emotional regulation, and organization
because their prefrontal cortexes are immature.

limbic system at puberty
prefrontal cortex by the early 20s

Neurological research finds that the reward parts of adolescents’ brains
are far stronger than the inhibition parts

In a survey
64 percent of U.S. 16- to 17-year-olds said they had been in a car when the driver was texting

Extensive research finds that four measures have saved hundreds of lives of teenage drivers
(1) requiring more time between issuing a learner’s permit and granting a full license, (2) no driving at night, (3) no teenage passengers, and (4) zero tolerance for alcohol and driving

adolescent egocentrism
A characteristic of adolescent thinking that leads young people (ages 10 to 13) to focus on themselves to the exclusion of others.

Egocentrism leads adolescents
nterpret everyone else’s behavior as if it were a judgment on them

Elkind named several aspects of adolescent egocentrism
personal fable and the invincibility fable

personal fable:
An aspect of adolescent egocentrism characterized by an adolescent’s belief that his or her thoughts, feelings, and experiences are unique, more wonderful or awful than anyone else’s.

invincibility fable:
An adolescent’s egocentric conviction that he or she cannot be overcome or even harmed by anything that might defeat a normal mortal, such as unprotected sex, drug abuse, or high-speed driving.

imaginary audience
he other people who, in an adolescent’s egocentric belief, are watching and taking note of his or her appearance, ideas, and behavior. This belief makes many teenagers very self-conscious

Jean Piaget: Adolescents move past concrete operational thinking
and consider abstractions

formal operational thought
In Piaget’s theory, the fourth and final stage of cognitive development, characterized by more systematic logical thinking and by the ability to understand and systematically manipulate abstract concepts.


By age 10,
children thought about location, but used trial and error, not logic.

Finally, by about age 13 or 14
some children hypothesized and tested the reciprocal relationship between weight and distance and developed the correct formula

formal operational
adolescents imagine all possible determinants…[and] systematically vary the factors one by one, observe the results correctly, keep track of the results, and draw the appropriate conclusions

One hallmark of formal operational thought is the
capacity to think of possibility, not just reality.

hypothetical thought:
Reasoning that includes propositions and possibilities that may not reflect reality.

Adolescents are primed to engage in hypothetical thought
reasoning about if-then propositions that do not reflect reality. For example, consider this question

In developing the capacity to think hypothetically
adolescents gradually become capable of deductive reasoning,

deductive reasoning: top-down reasoning.
Reasoning from a general statement, premise, or principle, through logical steps, to figure out (deduce) specifics. (Also called top-down reasoning.)

Deductive reasoning begins with an
abstract idea or premise and then uses logic to draw specific conclusions

inductive reasoning:during the primary school years
Reasoning from one or more specific experiences or facts to reach (induce) a general conclusion. (Also called bottom-up reasoning.)

Among those who believed there were marked inequalities, more older adolescents (age 16 to 17) supported systemic solutions
than did younger adolescents (age 14 to 15).

during adolescence, cognitive development facilitates the understanding that discrimination exists at the social-systemic level

dual-process model:
he notion that two networks exist within the human brain, one for emotional and one for analytical processing of stimuli.

These two processes have been called:
intuitive/analytic, implicit/explicit, creative/factual, contextualized/decontextualized, unconscious/conscious, hot/cold, gist/quantitative, emotional/intellectual, experiential/rational, or system 1/system 2.

adolescents are particularly likely to use intuition, not analysis

intuitive thought called a heuristic
hought that arises from an emotion or a hunch, beyond rational explanation, and is influenced by past experiences and cultural assumptions.

analytic thought
Thought that results from analysis, such as a systematic ranking of pros and cons, risks and consequences, possibilities and facts. Analytic thought depends on logic and rationality.

Experiences and role models influence the choice.
Of whether to use analytic thought or intuitive thought

Paul Klaczynski has conducted dozens of studies comparing the thinking of children, young adolescents, and older adolescents
most adolescents (73 percent) made at least one analytic errorKlaczynski found that almost all adolescents were analytical and logical on some of the 19 problems but not on others. Logical thinking improved with age and education, although not with IQ.

In other words, being smarter as measured by an intelligence test did not advance logic as much as did having more

Klaczynski (2001) concluded that, even though teenagers can use logic,
“most adolescents do not demonstrate a level of performance commensurate with their abilities” (p. 854).

Essentially, analytic thought is more difficult than intuition,
and it requires examination of comforting, familiar prejudices.

Once people of any age reach an emotional conclusion (sometimes called a “gut feeling”),
they resist changing their minds.

Uneven brain development characterizes adolescence, with the limbic system developing faster than the prefrontal cortex.
Young adolescents are often egocentric, thinking of themselves as invincible, and performing for an imaginary audience.

Adolescents are also capable of logical, hypothetical thought, what Piaget described as formal operational thinking.
Both emotional intuition and logical analysis are stronger in adolescence than earlier in life. Adolescents usually prefer the former because it’s faster and easier.

Secondary education
traditionally grades 7 through 12—denotes the school years after elementary or grade school and before college or university

serious hearing loss in late adulthood is twice as common among those who never graduated from high school as it is among high school graduates
Global economic growth depends on highly educated workers. Partly because political leaders recognize that educated adults advance national wealth and health, every nation is increasing the number of students in secondary schools.

Education is compulsory until at least age 12 almost everywhere

Many developmentalists find middle schools to be
“developmentally regressive

Evidence shows that for non-human animals
when under stress, learning slows down at puberty (

However, many experts do not believe the biological or psychological stresses of puberty are the main reasons learning suffers in early adolescence
Instead, they blame the organizational structure of many middle schools

many middle school students seek acceptance from their peers.
Bullying increases, appearance becomes important, status symbols are displayed (from gang colors to expensive shoes), and sexual conquests are flaunted, with boys bragging and girls gaining status if they have older boyfriends.

In fourth grade, the “coolest” peers are good students;
by eighth grade, cool peers are not involved in school but likely to be antisocial

middle school students,
A cognitive perspective on development highlights the academic disengagement typical of

entity approach to intelligence
An approach to understanding intelligence that sees ability as innate, a fixed quantity present at birth; those who hold this view do not believe that effort enhances achievement.

incremental approach to intelligence:
An approach to understanding intelligence that holds that intelligence can be directly increased by effort; those who subscribe to this view believe they can master whatever they seek to learn if they pay attention, participate in class, study, complete their homework, and so on.

If a school is structured so that children individually compete with each another rather than work in cooperative groups, then individuals who score low are likely to cope
by endorsing the entity theory

According to international comparisons, educational systems that track students into higher or lower classes, that expel students who are not learning, and that allow competition between schools for the brightest students
are also school systems with lower average achievement and a larger gap between student scores at the highest and lowest quartiles

The larger and less personal the new institution is, and the more egocentric the student is,
the more difficult the transition.

When students enter a new school with classmates and customs unlike those in their old school, minority students
stereotype threat,

Depression, self-injury behavior, substance abuse, eating disorders, bipolar disorder, and schizophrenia have striking developmental patterns corresponding to
transitions in early and late adolescence.

after eighth grade,
children seem to learn more

Bullying decreases each year of elementary school,
perhaps because students learn from classmates and teachers that there are better ways to interact with other children.

many studies find that bullying increases in the first year of middle school and again in the first year of high school
his occurs between the sexes as well as within them, with girls likely to bully other girls they perceive as sexual rivals, and boys likely to bully other boys they perceive as gay.

Bullying that occurs when one person spreads insults or rumors about another by means of technology (e.g., e-mails, text messages, or cell phone videos).

cyberbullying is worse when
the self-image is forming, the imaginary audience is looming, and impulsive thinking often supersedes analytic thinking in early adolescence

Then students consider their school a good place to be—with supportive teachers, friendly students, opportunities for growth-those with high self-esteem are
not only less likely to engage in cyberbullying, but they also disapprove of it

when the school climate is negative, those with high self-esteem are often bullies
analytic, deductive thinking makes sense since many 15- to 18-year-olds are capable of abstract logi

From a developmental perspective, the fact that high schools emphasize

high-stakes test:
An evaluation that is critical in determining success or failure. If a single test determines whether a student will graduate or be promoted, it is a high-stakes test.

PISA (Programme for International Student Assessment):
An international test taken by 15-year-olds in 50 nations that is designed to measure problem solving and cognition in daily life.

Career Academies
prepare students for specific jobs

he disparity in teacher quality between wealthy and impoverished schools is much greater in the United States than
in nations that score high on the PISA

guidance counselors in the United States have an average caseload
of 270 students

was designed to measure the cognitive abilities needed in adult life, not necessarily the ones that help students in college classes.

The PISA is taken by

Overall, the U.S. students did worse on the PISA than on the

Analysis of nations and scores on the PISA finds four factors that correlate with high achievement (OECD, 2010, p. 6)
Leaders, parents, and citizens overall value education, with individualized approaches to learning so that all students learn what they need.

Standards are high and clear, so every student knows what he or she must do, with a “focus on the acquisition of complex, higher-order thinking skills.”

Teachers and administrators are valued, given “considerable discretion…in determining content” and sufficient salary as well as time for collaboration.

Learning is prioritized “across the entire system,” with high-quality teachers working in the most challenging environments.

students who are capable of passing their classes drop out almost as often as those who are less capable, at least as measured on IQ tests.
Persistence, engagement, and motivation seem more crucial than intellectual ability

Students were most motivated and engaged in primary school, somewhat engaged in college, but least engaged in secondary school (Martin, 2009).
alues embraced during adolescence are more likely to endure than those acquired later, after brain connections are firmly established

At every age, the best thinking may be “fast and frugal”

A detailed calculation found that if the United States’ average PISA score increased by a mere 25 points
that would result in an increase of $40 trillion in the nation’s GDP (gross domestic product, which measures economic production)

Secondary education is crucial for personal health and for national economic development.
Many students become alienated from learning during middle school; middle schools are not usually organized to encourage relationships between teachers and students.

Transitions to new schools are always challenging, as illustrated by the increase in bullying, especially cyberbullying, as middle school begins.
High-stakes national tests required for high school graduation, and international tests such as the PISA, raise questions about the quality of secondary education in the United States.

Adolescents are capable of intense learning of new ideas and of questioning traditional beliefs.

Adolescents believe that others:
are as egocentric as they are

What function does the prefrontal cortex serve?
It is responsible for planning ahead and emotional regulation.

At which of the following ages would you expect acute self-consciousness to be at its highest?
12 years

Since adolescents regard themselves as uniquely special:
it is difficult for them to envision another person’s perspective.

Using _____ thinking, a person might think, “If it barks like a dog and wags its tail like a dog, it must be a dog.”
D. inductive

The fact that the prefrontal cortex is the last to mature may explain something that has long bewildered adults: Many adolescents are driven by the excitement of new experiences and sensations—forgetting the caution that their parents have tried to instill (Steinberg, 2008).