CHAPTER 11
PHYSICAL AND COGNITIVE
DEVELOPMENT IN ADOLESCENCE
Learning Objectives
PHYSICAL MATURATION
Physical Manifestations of Puberty
Rapid growth
Development of
primary and
secondary sex
characteristics
Changes in
body
composition
Changes in
circulatory and
respiratory
systems
Growth during Adolescence: The Rapid Pace
of Physical and Sexual Maturation
Adolescent growth spurt
• Weight increase
• Skeletal changes
• Accelerated
• Asynchronicity in growth
Growth Pattern
What is a secular trend?
• Earlier start of puberty is example of significant secular
trend
– Pattern of change occurring over several generations
– Trends occur when physical characteristic changes
over course of several generations
– Result of better nutrition over centuries
Puberty in Girls
Begins earlier for girls than for boys
• Girls start puberty at around age 11 or 12, and boys
begin at around age 13 or 14
• Wide variations among individuals
Influences
• Nutrition
• Health
• Environmental stress
Onset of Menarche
• Varies in different
parts of world
• Begins later in
poorer, developing
countries
• Influenced by
proportion of fat to
muscle in body
• Related to
environmental
stress
Puberty in Boys
• Penis and scrotum begin to grow at accelerated rate
around age 12 and reach adult size about 3 or 4 years
later
• Enlargement of prostate gland and seminal vesicles
• Spermarche around age 13
Primary Sex Characteristics
Further development of sex glands
• Testes in males
• Ovaries in females
Secondary Sex Characteristics
• Changes in genitals and breasts
• Growth of hair:
– Pubic
– Facial
– Body
• Further development of sex organs
Body Image: Reaction to Physical Changes in
Adolescence
Some of the changes of adolescence do not show up in
physical changes, but carry psychological weight
• Menstruation and ejaculations occur privately, but
changes in body shape and size are public
• Teenagers entering puberty frequently are embarrassed
by the changes
• Girls are frequently unhappy about their changing bodies
Sexual Maturation
Timing and Tempo of Puberty
• Variation of timing and tempo great
• No relationship between onset and rate of pubertal
development
• Some differences; causes are inconclusive
Consequences of Early and Late Maturation
Early maturation: Boys
Conspicuousness
of their deviance
Early-maturing
More apt to have
from their laterThey also tend to
boys tend to be
difficulties in
maturing
more successful at be more popular
school, and they
classmates may
athletics,
are more likely to
and to have a
have a negative
presumably
more positive self- become involved
effect, producing
concept
because of their
in delinquency and
anxiety,
larger size
substance abuse.
unhappiness, and
depression
The Consequences of Early and Late
Maturation
Early maturation: Girls
Obvious changes in their
bodies—such as the
development of
breasts—may lead them
to feel uncomfortable and
different from their peers
May have to endure
ridicule from their less
mature classmates
Tend to be sought after
more as potential dates,
and their popularity may
enhance their selfconcepts.
The Consequences of Early and Late
Maturation
Late Maturation: Boys
Boys who are
smaller and
lighter than their
more physically
mature peers tend
to be viewed as
less attractive
Disadvantage
when it comes to
sports activities
and social
activities
Decline in selfconcept
positive qualities,
such as
assertiveness and
insightfulness, and
they are more
creatively playful
than early
maturers
The Consequences of Early and Late
Maturation
Late Maturation: Girls
May be overlooked in
dating and other mixedsex activities during
junior high school and
middle school, and they
may have relatively low
social status
Satisfaction with
themselves and their
bodies may be greater
than that of early
maturers
Fewer emotional
problems
Nutrition, Food, and Eating Disorders:
Fueling the Growth of Adolescence
Fueling the Growth of Adolescence
For most adolescents, the major nutritional issue is
ensuring the consumption of a sufficient balance of
appropriate foods
• Rapid physical growth of adolescence is fueled by an increase in
food consumption
• Particularly during the growth spurt, adolescents eat substantial
quantities of food, increasing their intake of calories rather
dramatically
– During the teenage years, the average girl requires some 2,200
calories a day
– The average boy requires 2,800
• Several key nutrients are essential, including, in particular, calcium
and iron
Nutritional Problems in Adolescence
Poor eating habits
• High consumption of junk food/sugar/fats
• Large portion sizes
• Lack of variety
Related health concerns
• Obesity
• Osteoporosis
• Diabetes
• Heart disease
Pubertal Changes and Eating Disorders
Obesity
Bulimia
Anorexia
Nervosa
Pubertal Changes and Eating Disorders
• Ratio of body fat to
muscle increases
• Basal metabolism
rate decreases
• Overall physical
appearance
changes
• 20% overweight;
5% obese; 15%
seriously
overweight
Anorexia Nervosa and Bulimia
Definitions
• Anorexia=starvation to maintain low weight
• Bulimia=binge and purge eating
– 1% anorexic and 3% bulimic
– Higher incidence among females
• Disordered eating and body dissatisfaction reported
across socioeconomic lines
Brain Development and Thought: Paving the
Way for Cognitive Growth
A No Brainer?????
• Brain changes
• Growth spurts
• No clear 1:1 correspondence
Use It or Lose It
• Brain produces oversupply of gray matter during
adolescence which is later pruned back at rate of one to
two percent per year
• Myelination increases and continues to make
transmission of neural messages more efficient
How is this related to adolescent impulse
control?
• Prefrontal cortex
provides for impulse
control
• Adolescence prefrontal
cortex is biologically
immature = ability to
inhibit impulses is not
fully developed
Figure 11-5 Pruning Gray Matter
This three-dimensional view of the brain
shows areas of gray matter that are pruned
from the brain between adolescence and
adulthood. (Source: Sowell et al., 1999.)
The Immature Brain Argument: Too Young for
the Death Penalty?
Are the brains of adolescents so immature that
teenage offenders should receive less harsh
punishment for their crimes than those with older,
and therefore more mature, brains?
What do you think?
Yawning of the Age of Adolescence
Sleep Deprivation
• Adolescents go to bed later and get up earlier
•
Sleep deprivation takes its toll
– Lower grades
– More depressed
– Greater difficulty controlling their moods
– Greater risk for auto accidents
Review and Apply
REVIEW
• Adolescence is a period of ___ physical growth, including
the changes associated with ___.
• Puberty can cause reactions in adolescents ranging from
___ to increased ___ ___.
• ___ or ___ maturation can bring advantages and
disadvantages, depending on ___ as well as emotional and
psychological maturity.
• Adequate ___ is essential in adolescence because of the
need to fuel ___ growth.
• Changing physical needs and environmental pressures can
induce ___ or ___ ___.
Review and Apply
REVIEW
• The two most common eating disorders are
___ ___ and ___. Both must be treated with a
combination of ___ and ___ therapies.
• ___ development paves the way for significant
cognitive growth.
Review and Apply
APPLY
• How can societal and environmental influences
contribute to the emergence of an eating
disorder?
COGNITIVE DEVELOPMENT AND SCHOOLING
Cognitive Development
Approaches
• Piaget
• Information processing
• Adolescent egocentrism
Piagetian Perspective
• Fixed sequence of qualitatively different stages
• Fundamentally different than child thinking
• Utilized in variety of settings and situations
Piagetian Stages Related to Youth
Development
Formal operations
• 11+ years
• Development of abstract and hypothetical reasoning
• Development of propositional logic
• Cultural differences in use
Developmental of Formal Operations
Emergent
• Early adolescence
• Variable usage depends on conditions surrounding
assessment
Established
• Late adolescence
• Consolidated and integrated into general approach to
reasoning
Consequences of Adolescents’ Use of Formal
Operations
Ability to reason abstractly, embodied in their use of
formal operations, leads to a change in their everyday
behavior
• Questioning parents and authority figures
• Exhibiting greater idealism and impatience with
imperfections
• Experiencing indecision
Piaget…Pros and Cons
Pros
• Catalyst for much
research
• Accounts for many
changes observed
during adolescence
• Helps explain
– Developmental
differences
– Multidimensionality
– Metacognition
Cons
• Fails to prove
– Stage like fashion of
cognition
– FO is adolescent
cognitive stage
• Fails to account for
variability
– Between children
– Within child
– Within specific situations
Information Processing Perspectives: Gradual
Transformations in Abilities
• Changes in adolescents’ cognitive abilities are evidence of
gradual transformations in the capacity to take in, use, and
store information
• Number of progressive changes occur in the ways people
organize their thinking about the world, develop strategies for
dealing with new situations, sort facts, and achieve advances
in memory capacity and perceptual abilities
• Incorporates same techniques to understanding human
reasoning that computer scientists employ in writing programs
Changes in Information Processing
• Gains during adolescence help to explain developmental
differences in abstract, multidimensional, and
hypothetical thinking
• Store of knowledge increases as the amount of material
to which they are exposed grows and their memory
capacity enlarges
Egocentrism in Thinking: Adolescents’ SelfAbsorption
• New abilities make adolescents particularly introspective
and self-conscious
• These hallmarks of may produce a high degree of
egocentrism
• Adolescent egocentrism is a state of self-absorption in
which the world is viewed as focused on oneself
– Imaginary audience
– Personal fables
Thinking about Thinking…
Metacognition improves during adolescence
• Thinks about own thoughts  self-consciousness
• Monitors own learning processes more efficiently
• Paces own studying
School Performance
True or False?
Grades awarded to high school students have shifted
upward in the last decade.
School Performance
Do higher grades mean smarter students?
• Independent measures of achievement, such as SAT
scores, have not risen
• Consequently, a more likely explanation for the higher
grades is the phenomenon of grade inflation
• According to this view, it is not that students have
changed, but grades have been inflated
• This is future supported by comparison of U.S. students
to those in other countries
Students Around the World
Figure 11-6 U.S. 15-Year-Old
Performance
Compared with Other Countries
When compared to the academic
performance of students across the
world, U.S. students perform at belowaverage levels.
(Source: Based on National Governors
Association,
2008.)
The Lazy Days of Summer
Summer learning loss
• Socioeconomic differences
Remedy
• Summer enrichment programs
• Stealth learning/Not traditional summer school
Socioeconomic Status and School
Performance
Individual Differences in Achievement
• Children living in poverty lack many advantages
• Later school success builds heavily on basic skills
presumably learned or not learned early in school
Ethnic and Racial Differences in School
Achievement
Significant achievement differences between ethnic
and racial groups
• On average, African American and Hispanic students
tend to perform at lower levels, receive lower grades,
and score lower on standardized tests of achievement
than Caucasian students
• Asian American students tend to receive higher grades
than Caucasian students
What is the source of such ethnic and racial
differences in academic achievement?
Achievement Testing in High School: Will No
Child Be Left Behind?
No Child Left Behind Act
• Passed by Congress in 2002, requires that every U.S. state
design and administer achievement tests that students must
pass in order to graduate from
• high school
• Schools are graded so that the public is aware of which
• schools have the best (and worst) test results
Unintended consequences
• Teaching to test
• Approaches to teaching designed to foster creativity and
critical thinking discouraged
• Anxiety level raised in students
Adolescent Media Usage
Kaiser Family Foundation survey
• Young people spend an average of 6.5 hours a day with
media
• Around a quarter of the time they are using more than
one form of medium simultaneously, they are actually
being exposed to the equivalent of 8.5 hours per day
• Some teenagers send nearly 30,000 texts a month
See Figure 11-7 for additional information on teenagers,
cell phones, and texting
The Downside of Click
• Objectionable material available
• Growing problem of Internet gambling
• Safety
• Digital divide
Dropping Out of School
Adolescents leave school for variety of reasons
• Males are more likely to drop out of school than females
• Hispanics and African American students still are more
likely to leave high school before graduating than nonHispanic white students
• Not all minority groups show higher dropout rates:
Asians, for instance, drop out at a lower rate than
Caucasians
• Poverty plays larger role in higher dropout rate
Review and Apply
REVIEW
• Adolescence corresponds to Piaget's ___ ___ period,
a stage characterized by ___ ___ and an
experimental approach to problems.
• According to the information processing perspective,
the cognitive advances of adolescence are ___ and
___, involving improvements in many aspects of
thinking and ___.
• Improved ___ enables the monitoring of thought
processes and of mental capacities.
Review and Apply
REVIEW
• Adolescents are susceptible to adolescent ___
and the perception that an ___ ___ is
constantly observing their behavior.
• They also construct ___ ___ that stress their
uniqueness and immunity to harm.
• Academic performance is linked in complex
ways to ___ ___ and to ___ and ___.
Review and Apply
APPLY
• When faced with complex problems, such as
what kind of computer or car to buy do you
think most adults spontaneously apply formal
operations like those used to solve the
pendulum problem? Why or why not?
THREATS TO ADOLESCENTS’ WELL-BEING
Adolescent Drug Use
• One in 15 high school seniors smokes marijuana on a
daily or near-daily basis
• Marijuana usage has increased over the last few years
• Daily marijuana use is at a 30-year high for high school
seniors
How Common is Illegal Drug Use during
Adolescence?
Figure 11-8
Downward Trend
According to an
annual survey, the
proportion of
students reporting
marijuana use over
the past 12 months
has decreased since
1999.
What might account
for the decline in
drug use?
(Source: Johnston et
al., 2011.)
Why Do Adolescents Use Drugs?
•
•
•
•
Pleasurable experience
Escape
Peer pressure
Enhanced academic performance
Why Do Adolescents Use Drugs?
Biological and psychological addiction
• Addictive drugs are drugs that produce a biological or
psychological dependence in users, leading to
increasingly powerful cravings for them.
Why do adolescents use drugs?
• Psychological
addictiondepend on
drugs to cope with
everyday stress of
lifeprevent adolescents
from confronting—and
potentially solving—
problems that led them to
drug use in first place.
• Biological addiction
presence in body
becomes so common that
body is unable to function
in their absence; causes
actual physical—and
potentially lingering—
changes in nervous
system. drug intake no
longer may provide a
“high,” but may be
necessary simply to
maintain the perception of
everyday normalcy.
Alcohol: Use and Abuse
Figure 11-9 Binge
Drinking Among
College Students
For men, binge drinking
is defined as consuming
five or more drinks in one
sitting; for women, the
total is four or more.
Why is binge drinking
popular?
(Source: Wechsler et al.,
2003.)
Binge Drinking Effects on Brain
Binge drinking affects
certain areas of the
white matter of the
brain, as shown in this
scan.
(Source: McQueeny et al.,
2009, Figure 2)
Why do adolescents start to drink?
• Genetics
• Way of proving themselves
• Release of inhibitions and tension and reduction of
stress
• False consensus effect
From Activity to Addiction
Adolescent alcoholics
• Alcohol use becomes uncontrollable habit
• Increasing ability to tolerate alcohol
• Increasing need to drink ever-larger amounts of liquor to
bring about positive effects craved
Hooked on Drugs or Alcohol?
Signals
•Identification with the drug culture
•Signs of physical deterioration
•Dramatic changes in school performance
•Changes in behavior
(Adapted from Franck & Brownstone, 1991, p. 593–594)
Tobacco: The Dangers of Smoking
• Incidence
• Differences
– Gender
– International
– Racial
Why do adolescents begin to smoke and
maintain the habit?
• Advertisements in the media
• Addiction
• Parent and peer models
• Adolescent rite of passage
Selling Death: Pushing Smoking to the Less
Advantaged
• Tobacco companies carve out new markets by turning to
least advantaged
• Tobacco companies aggressively recruit adolescent
smokers abroad
Sexually Transmitted Infections
AIDS
• Leading cause of death among young women worldwide
• Already, over 25 million people have died from AIDS
worldwide, and people living with the disease number 34
million worldwide
AIDS Around the World
The number of people carrying the AIDS virus varies substantially by geographic
region. By far the most cases (Source: UNAIDS & World Health Organization, 2009.)
Other Sexually Transmitted Infections
Human
papilloma virus
(HPV)
Trichomoniasis
Genital herpes
Gonorrhea and
syphilis
Sexually Transmitted Infections (STIs) Among
Adolescents
Why are adolescents in particular in danger of contracting an STI?
(Sources: Alan Guttmacher Institute, 2004; Weinstock, Berman, & Cates,
2006.)
Avoiding STIS
Review and Apply
REVIEW
• Illegal drug use is prevalent among adolescents
as a way to find ___, avoid ___, or gain the ___
of peers.
• The use of ___ is also popular among
adolescents, often to appear adult or to lessen
___.
• Despite the well-known dangers of ___,
adolescents often smoke to enhance their
images or emulate adults.
Review and Apply
REVIEW
• AIDS is the most serious of the sexually
transmitted infections, ultimately causing death.
• Safe sex practices or ___ ___can prevent AIDS,
although adolescents often ___ these strategies.
• Other sexually transmitted infections affect
adolescents, such as ___, ___ ___, ___, ___,
and ___.
Review and Apply
APPLY
• How do adolescents’ concerns about selfimage and their perception that they are the
center of attention contribute to smoking and
alcohol use?
EPILOGUE
Before turning to the next chapter, return for the moment to the
opening prologue of this chapter, about Beth and Bryce
Chadwick's the following questions about Peter.
• Is Beth Chadwick right to be worried about the changes she
sees in her son Peter?
• Is Peter Chadwick's withdrawal from his family normal for a
boy his age? Why might he be spending so much time in his
room with the door closed?
• What other changes might be occurring to Peter apart from
the behavioral and personality changes mentioned by his
parents?
EPILOGUE
• What factors might be influencing Peter's declining
school performance?
• What advice would you give Peter's parents to deal with
the changes they see in Peter?