Introduction

• Adolescence, the period from roughly age 12 through the late teens, is a time of great change, with close connections between physical and psychological development. New cognitive skills emerge too, such as the ability to reason abstractly.
• Until the early twentieth century adolescence was not regarded as a distinct developmental period. Before then, reproductive maturity marked entry into adulthood, not into a transitional phase.
• G. Stanley Hall inspired much change in the way we perceive adolescence. Storm and stress was his theme.
• Adolescence is a longer time period than in Hall's day, partly because of earlier puberty and partly because of the number of years required for education.
• Substages of adolescence: early adolescence (puberty to age 13), middle adolescence (ages 14 - 16), late adolescence (17 to early adulthood).

• Puberty: Norms and Individual Differences
1. Puberty is the period during which a young person becomes capable of reproduction. The clearest markers of this change are menarche for girls, although girls do not reached reproductive maturity until they ovulate, and spermarche for boys, first ejaculation of mobile sperm.
2. Rather than a single event, puberty is best thought of as an extended period that begins during early adolescence (note: first hormonal changes can begin as early as age 7 or 8) and the latest phases can continue into mid-adolescence, when sexual organs and other sexual characteristics are developing rapidly.
3. There are sex differences in the timing of puberty. Onset is influenced by heredity, nutrition, stress, and exercise.
4. There are individual differences in the timing of puberty. Normal (= 95% of the population) menstruation begins between ages 9 and 16, and normal sperm production between 10 and 19. There has been a trend toward earlier puberty for at least the last 100 years in industrialized countries.
5. Improved nutrition and health have influenced the changes in the timing of puberty.
• Hormonal Control of Puberty
1. Puberty is the final stage in a much longer process of sexual development, beginning soon after conception when the amount of androgens determines development of male or female sex organs. At puberty, hormones again govern sexual changes.
2. The changes of puberty are governed by hormones operating in a feedback system involving the pituitary gland, hypothalamus, gonadotropins, and gonads. At the end of middle childhood the brain directs the gonads to step up production of sex hormones.
3. It was once thought that the hormonal changes of puberty were triggered by body weight (critical weight hypothesis), but the critical factor is now thought to be the proportion of fat to body mass or some other related factor.
• Changes in Appearance at Puberty
1. In addition to the development of reproductive capacities, the physical changes of puberty also include the emergence of secondary sex characteristics. There are five stages of pubertal development involving these sex characteristics.
2. Acne may develop and new body odors are noted.
3. A major growth spurt occurs, 2 years earlier for females. Growth occurs near the epiphyseal growth plates. See increases in weight, strength, and endurance.
• Neurological Changes at Puberty
  Between childhood and adolescence the brain shows 1) decline in plasticity and 2) increase in efficiency of brain functioning.
  
• Hemispheric specialization may contribute to a loss of plasticity.
• Decrease in the number of synapses is likely a contributor. Between ages 10 and 14, there is a 50 % drop in the energy being used in certain parts of the cortex.
• Decrease in synapses allows for more efficient functioning of the remaining connections.
• Sleep patterns also support the idea of brain changes at puberty; deep sleep levels reach that of adult patterns by ages 11 to 14.
• Impacts of Pubertal Change
1. Some behavioral changes of adolescence are more clearly associated with pubertal status, the timing of maturation, than with chronological age or cognitive development.
2. Puberty and Body Image
• Body image is strongly affected by puberty and its timing. In early adolescence, boys who are more physically mature are more likely to have a positive body image and to perceive themselves as generally more attractive than are boys who are less physically mature.
• For girls early puberty tends to be associated with a poorer body image, emphasis on being too heavy, though they are happier with breast development. Among early adolescent girls, those who are about average in physical development generally have the most positive body image and the greatest feelings of attractiveness.
3. Puberty and Social Relationships
• Puberty is associated with increased interest in the opposite sex and an increased likelihood of dating and sexual activity.
• Pubertal change and the timing of puberty also affect parent-child relationships, particularly in the area of autonomy. Parent-child conflicts are greatest with early maturers.
4. Puberty and Problem Behaviors
   A number of studies have documented an increase in various problem behaviors at puberty, especially in early-maturing girls. They are more likely to have children earlier and to complete fewer years of education.
   
5. Timing of Puberty and Overall Adjustment
• The timing of puberty has different effects for overall adjustment of boys and girls. Early-maturing girls have lower self-esteem and are more at risk for emotional problems. Late-maturing boys are less popular and less self-confident.
• Early-maturing females can reach puberty at age 9 and late-maturing males can reach puberty as late as age 19.
6. Direct and Indirect Effects of Puberty
   Puberty produces both unseen internal and visible external physical changes in adolescents. The internal changes may directly affect adolescents' feelings and behaviors through the influences of hormones. The external changes may affect feelings and actions too, both through the impact they have on an adolescent's own body image and through the reactions they trigger in others.
   

• Three major cognitive advances during adolescence are:
1. An increased ability to apply logical thinking to the possible, not just to the real (deal with necessary not just contingent truth).
2. The ability to think about relationships among mentally constructed concepts (abstract).
3. Thinking becomes even more logical and systematic than it was in childhood. They engage in hypothetico-deductive reasoning. Can think of hypothetical solutions to a problem. Developmentalists are still trying to determine what underlies these cognitive changes.
• Piaget's Theory of Formal Operations
1. Piaget explained adolescents' new thinking skills as a product of their ability to use formal operations. These cognitive structures are qualitatively different from those acquired earlier in childhood, but they result from the same developmental processes (equilibration, etc.).
2. Believed that formal operations could not be taught.
3. Piaget's Experiments
• Piaget's theory of formal operations is based on studies of adolescents' reasoning on tasks related to various scientific principles. These tasks used in Piaget's experiments demonstrated adolescents' use of one or more general cognitive abilities.
• The Law-of-Floating-Bodies Study
  Adolescents become able to see how two or more mentally constructed concepts can be related to produce a third even more abstract concept. Thus, in the floating-bodies task, they grasp that the ratio of weight to volume yields the concept of density.
  
• The Pendulum Study
  The pendulum task measures the ability to investigate the effects of a single variable while holding all other factors constant. Adolescents systematically test each of four relevant factors while holding the others constant and are thus able to discover the right answer.
  
• The All-Possible-Combinations Study
  By mid-adolescence, children adopt a systematic approach and try all possible combinations in order to discover which combination of five different colorless liquids causes a yellow color to appear.
  
• Is Piaget's View Correct?
1. Piaget's description of adolescent thinking abilities has proven to be quite accurate, but his explanation of these abilities has been criticized.
2. How Pervasive are Formal Operations?
• Emergent formal operations are typical in early adolescence while consolidated formal operations are more often used in mid to late adolescence.
• Many adolescents and adults do not use formal operations in routine problem solving. Their everyday cognitive performance does not seem to match their cognitive competence.
• Formal operations are more culture-bound than earlier cognitive abilities in his theory.
• Defenders of the theory say that the lack of pervasiveness of formal operations reflects the distinction between cognitive competence (optimal ability) and congitive performance (actual behavior in a particular situation).
3. Can Formal Operations Be Taught?
   Contrary to Piaget's predictions, some researchers have successfully taught the use of formal operations to older elementary school children and to adolescents who were not already using them.
   
4. Are Formal Operations Related to Academic Performance?
   Use of formal operations is positively related to general intelligence and to success in school, especially in math and science.
   
• Other Approaches to Adolescent Cognition
1. Information-Processing Explanations
• Research on adolescents' information-processing abilities consistently indicates continuing improvement in attention skills. Adolescents are better than younger children at both selective attention and divided attention.
• Adolescents also surpass younger children in the areas of short- and long-term memory. Improvements may be due to increases in memory capacity (6 items by age 9).
• Development of metamemory and increased sophistication in using mnemonic strategies account for much of the improvement in memory processes. Adolescents use more complex strategies, spontaneously, and become more planful and flexible in their memory strategy usage. They do show some metamemory limitations such as recognizing the most appropriate strategy.
• Increase in available cognitive processing capacity called automatization may also play a role. With more experience or practice, processes become less effortful.
• Another factor: expanding knowledge base.
2. Cognitive Socialization
• Cognitive socialization refers to the influence of social environment on the development of cognitive skills. The reason for much of the impact of social interaction on cognitive development is that it provides a setting for trying out ideas, responding to opposing points of view, and learning to evaluate the soundness of arguments and evidence.
• Adolescents do not simply invent principles of logical reasoning and effective approaches to problem solving on their own. Instead, especially during early adolescence, discussion with others, individually or in small groups, seems to foster the emergence of higher-order thinking skills.
• Schools play the most obvious role in adolescents' cognitive socialization. Emphasis on test score outcomes has detracted from the development of higher-order cognitive abilities such as critical thinking.
• In a variety of subject areas, including science, math, and social studies, adolescents in the United States show low levels of critical thinking. It is clear that critical thinking, like formal operations, does not automatically emerge in adolescence. Adolescents may fail to think critically for a number of reasons, both cognitive and social. Developmental psychologist Daniel Keating believes that critical thinking may be fostered by parents and teachers who provide specific experiences and learning contexts for adolescents.
• Television, especially commercials, has discouraged critical thinking and reasoned decision-making.

• Adolescent Egocentrism
1. Adolescents' new abilities for abstract thought give rise to a new form of egocentrism that includes concern about an imaginary audience, an unjustified concern that one is the focus of others' attention. They can think about thinking and thus can think about what others may be thinking about them.
2. Another aspect of adolescent egocentrism is the personal fable, the belief that they are unique and no one has ever had the same thoughts or feelings they are having. It is also related to feelings of invincibility to risks and physical dangers.
3. Much of this is due to their more abstract thinking about topics with which they have little experience (romantic love, sex).
4. The emergence of adolescent egocentrism may be associated with processes of identity development as well as with cognitive changes.
• Moral Reasoning
1. Moral reasoning - the process of thinking and making judgments about the right course of action in a given situation.
2. Piaget's Model
   Piaget discussed the development of moral reasoning within his broad theory of cognitive development. His model included an amoral stage (through age 7), a stage of moral realism (middle childhood), and a stage of autonomous morality (by early adolescence). Piaget believed that moral development is a direct consequence of both cognitive development and increased social experience.
   
3. Kohlberg's Model
   Kohlberg expanded on Piaget's approach to include six stages of moral development within three broader periods: preconventional morality, conventional morality, and postconventional or principled morality. Most adolescents and adults operate at the level of conventional morality where moral judgments are based on internalized standards arising from concrete experience with the world-focuses on opinions of others or on formal laws.
   
4. Criticisms of Kohlberg's Model
   Piaget's and Kohlberg's models have both been criticized because of the weak relationship between moral reasoning and moral behavior. Kohlberg's theory has also been criticized for separating the form and content of moral reasoning, for the reliability of his measures, for bias against women, and for being too culture-specific.
   

• Physical changes that occur during adolescence are a good example of qualitative change; puberty produces a transformation in a young person's physical appearance and a reorganization of his or her functioning. These physical changes have far-reaching implications for other areas of an adolescent's life.
• Cognitive abilities also undergo qualitative changes by the end of adolescence.