Chapter 11
Physical and Cognitive
Development in Adolescence
©2005 McGraw-Hill Ryerson Ltd.
Physical and Cognitive
Development in Adolescence
The Nature
Of Adolescence
Adolescent
Cognition
Adolescent Health
Problems and
Wellness
Puberty
Adolescent
Sexuality
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Nature of Adolescence
• Genetic, biological, environmental, and social
factors interact in teen development.
• Continuity and discontinuity both play a role.
• Relationships with parents take a different form.
• Dating occurs for the first time.
• Thoughts are more abstract and idealistic.
• Biological changes trigger a heightened interest
in body image.
• Most adolescents have a positive self-concept
and positive relationships with others.
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Puberty
Individual
Variation
Early and
Late Maturation
Hormonal
Changes
Body
Image
Height, Weight,
and Sexual Maturation
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Definition of Puberty
• Puberty is a period of
rapid physical
maturation involving
hormonal and bodily
changes that occur
primarily during early
adolescence.
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Individual Variation in Puberty
• Boys – pubertal sequence begins between ages
10 and 13 ½
• Girls – normal range is between 8 and 16 (onset
of menarche, or first menstrual period).
• Puberty determinants include:
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Nutrition
Health
Heredity
Body mass
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What are Hormones?
• Powerful chemical substances secreted by
the endocrine glands and carried through
the body by the bloodstream
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Endocrine System
• Hypothalamus – a structure in the higher
portion of the brain that monitors eating,
drinking, and sex
• Pituitary gland – an endocrine gland that
controls growth and regulates other glands
• Gonads – the sex glands (testes in males,
ovaries in females)
• Gonadotropins – hormones that stimulate
the testes or ovaries
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Hormonal Changes
• The endocrine system’s role in puberty involves
interaction of the hypothalamus, pituitary gland,
and gonads.
• The pituitary gland also interacts with the thyroid
gland to produce growth and skeletal
maturation.
• The concentrations of certain hormones
increase dramatically during adolescence.
• Hormones contribute to both physical and
psychological development.
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Height and Weight
• Growth spurt – occurs about 2 years earlier for girls.
• Mean beginning of the growth spurt – age 9 for girls; age
11 for boys.
• Peak rate of pubertal change – age 11.5 for girls; age
13.5 for boys.
• Increase in height – about 9 cm per year for girls; about
10.6 cm for boys.
• The rate at which adolescents gain weight follows
approximately the same timetable as height.
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Sexual Maturation in Boys
• Increase in penis and testicle
size
• Appearance of straight pubic
hair
• Minor voice change
• First ejaculation
• Appearance of kinky pubic hair
• Onset of maximum growth
• Growth of hair in armpits
• More detectable voice change
• Growth of facial hair
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Sexual Maturation in Girls
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Breasts enlarge
Pubic hair appears
Hair appears in the armpits
Growth in height
Hips become wider than shoulders
First menstruation comes rather late in puberty
Menstrual cycles are often highly irregular
Some girls aren’t fertile until 2 years later
Breasts are fully rounded by the end of puberty
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Body Image
• Adolescents are preoccupied with their bodies and
develop individual images of what their bodies are like.
• Adolescents are more dissatisfied with their bodies
during puberty than in late adolescence.
• Girls are less happy with their bodies and have more
negative body images than boys throughout puberty.
• As pubertal change proceeds, girls often become more
dissatisfied with their bodies due to the increase in body
fat, while boys become more satisfied due to the
increase in muscle mass.
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Early and Late Maturation in Boys
• Recent research confirms that during
adolescence, it is advantageous to be an
early-maturing rather than late-maturing
boy.
• Early maturing boys appear to perceive
themselves more positively and have more
successful peer relations than their latematuring counterparts.
©2005 McGraw-Hill Ryerson Ltd.
Early and Late Maturation in Girls
• Recent findings suggest that earlymaturing girls experience more problems
in school.
• They also experience more independence
and popularity with boys.
• In sixth grade, early-maturing girls show
greater satisfaction with their figures, but
by tenth grade, late-maturing girls are
more satisfied.
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Adolescent
Sexuality
Developing a
Sexual Identity
The Progression
of Adolescent
Sexual Behaviours
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Risk Factors
and Sexual
Problems
Adolescent Sexuality
• Adolescence is a time of sexual exploration and
experimentation.
• Adolescence is a bridge between the asexual
child and the sexual adult.
• Sexual development and interest are normal
aspects of adolescent development.
• The majority of adolescents have healthy sexual
attitudes and engage in sexual practices that will
not compromise their development.
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Developing a Sexual Identity
• An adolescent’s sexual identity
involves:
– an indication of sexual
orientation
– activities
– interests
– styles of behaviour
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The Progression of Adolescent
Sexual Behaviour
• Adolescents engage in a consistent progression
of sexual behaviours:
– Necking
– Petting
– Intercourse/Oral sex
• Eight in 10 girls are virgins at age 15.
• Seven in 10 boys are virgins at age 15.
• The probability that adolescents will have sexual
intercourse increases steadily with age.
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Risk Factors and Sexual Problems
• Adolescents who engage in sex before
age 16 are the least effective users of
contraception.
• They are also at risk for unintended
pregnancy and sexually transmitted
diseases.
• Early sexuality is also linked with
excessive drinking and drug use.
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Contraceptive Use
• Two kinds of risks that youth encounter:
– unintended/unwanted pregnancy
– sexually transmitted diseases
• Both of these risks can be reduced
significantly if contraception is used.
• Adolescents are increasing contraceptive
use.
• Younger adolescents are less likely to
use them.
• http://vad.mhhe.com/provided_module.cf
m?ModuleID=222 (Adolescents'
Changing Bodies: “Using
Contraception at Age 15”)
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Sexually Transmitted Infections and
Diseases
• Sexually transmitted diseases (STDs) are
contracted primarily through sexual contact,
which is not limited to sexual intercourse. Oralgenital and anal-genital contact also can be
involved in STDs.
• Chlamydia and gonorrhea are more common
among adolescents than young adults.
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Adolescent Pregnancy
• Each year, more than 40,000
Canadian teenagers become
pregnant.
• The teen pregnancy rate did
decline slightly in the 1990s.
• Most adolescent pregnancies are
unplanned.
• Regional differences exist across
Canada.
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Consequences of Adolescent
Pregnancy
• Adolescent pregnancy creates health risks for
both the offspring and the mother.
• Infants born to teen mothers are more likely to
have:
– low birthweights
– neurological problems
– childhood illness
• Adolescent mothers often drop out of school.
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Reducing Adolescent Pregnancy
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Sex education and family planning
Access to contraceptive methods
The life-options approach
Broad community involvement and support
Abstinence, especially for young
adolescents
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Adolescent Health
Problems and Wellness
Teen
Depression
Leading Causes of Death
In Adolescence
Substance Use
and Addiction
Eating
Disorders
Risk, Vulnerability, and the Roles of
Parents and Peers
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Teen Depression
• Depression is defined as experiencing
over a prolonged period of time a range of
symptoms including fatigue, irritability,
inability to make decisions, sleeping
problems, lack of interest in daily activities,
and suicidal thoughts.
• Boys were half as likely to suffer from
depression.
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Higher Rates of Depression in
Females
• Females tend to internalize emotions.
• Females tend to ruminate in their
depressed mood and amplify it.
• Females’ self-image, especially their body
images, are more negative than those of
males.
• Females face more discrimination than do
males.
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Substance Use and Addiction
• Dopamine in the
Brain
• Alcohol
• Cigarette Smoking
• Gambling
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Dopamine in the Brain
• Dopamine is one of the key brain
chemicals that carry and influence
messages between nerve cells.
• It is heavily involved with pleasure –
reward circuit of the brain.
• All addictive drugs artificially increase the
amount of dopamine in the reward centres
of the inner brain by either jump-starting
its release or prolonging its stay.
©2005 McGraw-Hill Ryerson Ltd.
Alcohol
• Alcohol is the drug most
widely used by
adolescents in our
society.
• Since 1980, alcohol
related deaths among
teenage drivers has
dropped by 61% in
Canada.
©2005 McGraw-Hill Ryerson Ltd.
Cigarette Smoking
• Begins primarily during childhood and
adolescence.
• A study found that once young adolescents
begin smoking, the addictive properties of
nicotine make it extremely difficult for them
to stop.
• The early age of onset of smoking is more
important in predicting genetic damage
than how much individuals smoke.
©2005 McGraw-Hill Ryerson Ltd.
Gambling
• Gambling is a hidden addiction because it
has no visible signals.
• About 80% of Canadians gamble.
• The number of pathological gamblers in
Canada may be as high as 1.2 million.
• Gambling has become increasingly
popular with high school students.
©2005 McGraw-Hill Ryerson Ltd.
Risk, Vulnerability, and the Role of
Parents and Peers
• Drug use in childhood or early adolescence has
more detrimental long-term effects on the
development of responsible, competent
behaviour than when drug use occurs in late
adolescence.
• Positive relationships with parents and others
are important in reducing adolescents’ drug use.
• Adolescents are most likely to take drugs when
both of their parents take drugs and when
their peers take drugs.
©2005 McGraw-Hill Ryerson Ltd.
Eating Disorders
• Anorexia Nervosa
• Bulimia Nervosa
• http://vad.mhhe.co
m/provided_modul
e.cfm?ModuleID=2
22 (Adolescents'
Changing Bodies:
“Eating
Disorders”)
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Anorexia Nervosa
• An eating disorder that involves the relentless pursuit of
thinness through starvation; can lead to death.
• Anorexics often weigh less than 85% of what is
considered normal.
• They have an intense fear of gaining weight, which does
not dissipate with weight loss.
• They also have a distorted image of their body shape
and constantly weigh themselves.
• Most are White adolescent or young adult females from
well-educated, middle and upper income families.
• They set high standards and stress at not reaching them.
©2005 McGraw-Hill Ryerson Ltd.
Bulimia Nervosa
• An eating disorder in which the individual consistently
follows a binge-and-purge eating pattern.
• Purging is accomplished through self-inducing vomiting
or use of a laxative.
• Most bulimics are females in their late teens or early
twenties.
• Most bulimics are preoccupied with food, have a strong
fear of becoming overweight, and are depressed or
anxious.
• Unlike anorexia, bingeing and purging occurs within a
normal weight range and is difficult to detect.
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Leading Causes of Death in
Adolescence
• Accidents – most involve automobiles, and are
the result of risky driving habits and driving
under the influence of alcohol or drugs.
• Suicide – accounts for 6% of the deaths in the
10–14 age group, and 12% of deaths in the 15 –
19 age group.
• Alcohol and Illicit Drug Use – being
under the influence of alcohol or drugs
may result in riskier behaviour, which in
turn results in more accident fatalities.
©2005 McGraw-Hill Ryerson Ltd.
Adolescent
Cognition
Piaget’s
Theory
Adolescent
Egocentrism
Information
Processing
©2005 McGraw-Hill Ryerson Ltd.
Education
Piaget’s Theory
• Adolescent thought is at the formal operational
stage.
• Thought is more abstract, characterized by:
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verbal problem-solving ability
increased tendency to think about thought itself
idealism and possibilities
more logical
hypothetical-deductive reasoning
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Hypothetical-Deductive Reasoning
• Piaget’s formal operational concept that
adolescents have the cognitive ability to
develop hypotheses, or best guesses,
about ways to solve problems, such as an
algebraic equation. They then
systematically deduce, or conclude, which
is the best path to follow in solving the
equation.
©2005 McGraw-Hill Ryerson Ltd.
Adolescent Egocentrism
• The heightened self-consciousness of
adolescents, reflected in their belief that
others are as interested in them as they
themselves are, and in their sense of
personal uniqueness.
• Dissected into two types of social thinking:
– imaginary audience
– personal fable
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Imaginary Audience
• Refers to the heightened selfconsciousness of adolescents,
reflected in their belief that others are as
interested in them as they themselves are.
• Involves attention-getting behaviour—the
attempt to be noticed, visible, and “on
stage.”
©2005 McGraw-Hill Ryerson Ltd.
Personal Fable
• The part of adolescent egocentrism
involving an adolescent’s sense of
uniqueness and invulnerability.
• Adolescents feel that no one can
understand how they really feel.
• Personal fables frequently show up in
adolescent diaries.
©2005 McGraw-Hill Ryerson Ltd.
Information Processing
• Decision Making
• Critical Thinking
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Decision Making
• Adolescence is a time of increased decision
making.
• Compared with children, young adolescents are
more likely to generate options, examine a
situation from a variety of perspectives,
anticipate the consequences of decisions, and
consider the credibility of sources.
• Parents should involve adolescents in
appropriate decision-making activities.
©2005 McGraw-Hill Ryerson Ltd.
Critical Thinking
• A solid basis of fundamental skills is necessary for the
development of critical thinking skills.
• Recent studies have shown critical thinking increases
with age, but still only occurs less than half the time with
eleventh grade students.
• Cognitive changes that allow improved critical thinking
are:
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increased speed and capacity of information processing
more breadth of content knowledge in a variety of areas
increased ability to construct new knowledge combinations
a greater range and more spontaneous use of strategies
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©2005 McGraw-Hill Ryerson Ltd.
Education
• Effective Schools
• High School
Dropouts
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Effective Schools
• Effective schools offer more than the “3 Rs”;
they are accountable and responsible to public
scrutiny.
• Trademarks of effective schools:
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Effective leadership
Clear academic goals
A safe and orderly climate
Expectation of minimum mastery of skills
Testing for program evaluation and redirection
Parental involvement
Collegiality
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Hidden Curriculum
• The “hidden curriculum” is conveyed by the moral
atmosphere that is a part of every school.
• The moral atmosphere is created by school and
classroom rules, the moral orientation of teachers and
school administrators, and text materials.
• Teachers serve as models of ethical and unethical
behaviour.
• Through rules and regulations, school administrations
infuse a school with a value system.
©2005 McGraw-Hill Ryerson Ltd.
High School Dropouts
• In the last 50 years the school completion rate in
Canada has increased from 50% to 80%.
• Almost 50% of those who leave school return by
age 20 to complete their high school education.
• Aboriginal youth have a disproportionately high
rate of leaving school – approximately 70%.
• Nova Scotia reports the lowest provincial
dropout rate of 13%.
©2005 McGraw-Hill Ryerson Ltd.
Who Leaves School?
• Characteristics of people who leave school:
– Are disabled
– Have dependants
– Have fathers that didn’t complete high school
– Have changed schools a number to times
– Live with friends or alone rather than with families
– Work
– Are male
– Live common law or have been separated or divorced
– Have parents or friends who do not consider school
important
©2005 McGraw-Hill Ryerson Ltd.