Chapter 4

Development of the Brain in Adolescence

Cell Proliferation, Synaptic Pruning, and Myelination: Brain development continues throughout adolescence, with different regions developing at different rates. Three related processes contribute to brain development in adolescence. Cell proliferation consists in the overproduction of neurons and their interconnections; synaptic pruning consists in the selective elimination of cells and their connections that are infrequently used; myelination consists in the formation of an insulating sheath along the length of a neuron’s axon. Theories can be verified or disconfirmed. Theories that derive from the same model reflect the assumptions characteristic of the model that generated them.
Key Terms: cell proliferation, cortical gray matter, synaptic pruning, myelination, white matter

The Prefrontal Cortex: Thinking Like an Executive: The prefrontal cortex continues to develop during adolescence. This area of the brain is responsible for abstract thought, planning, and anticipating the consequences of one’s actions.
Key Terms: prefrontal cortex, executive functions, multitasking

The Limbic System: Risk Taking: The limbic system is involved in the processing of social and emotional information. Because this region of the brain develops earlier than the prefrontal cortex, it dominates the executive controls of the prefrontal cortex in early adolescence, increasing the likelihood of risky decisions.
Key Terms: limbic system

How Adolescents Think

Thinking Abstractly: Going beyond what they were capable of thinking as children, adolescents can think of things in terms of class membership and can classify the classes. They can even think about thinking itself.

Thinking Hypothetically: Adolescents can think of things that are only possible but not necessarily real.
Key Terms: metacognition

Thinking Logically: Adolescents are able to test different ideas against one another to establish their truth.

Emerging Adulthood: Thinking Pragmatically and Tolerating Ambiguity: There are differences as well in the ways adolescents and emerging adults think. Perhaps the most noticeable of these is that emerging adults are more practical, such as realizing that not all of the logical alternatives one can think of are available.

Explaining Cognitive Development

A Constructive Perspective: The constructive perspective assumes that individuals interpret experience. Piaget applies this perspective to development by suggesting that our understanding of the world is organized in qualitatively different ways with age. Kegan suggests that intellectual growth takes place through a process of differentiation of self from other.
Key Terms: assimilation, accommodation, equilibration, differentiation, conservation

A Contextual Perspective: Vygotsky views knowledge as social in nature, taking place under the tutelage of another, as a natural consequence of working alongside someone who has more experience. Rogoff views the acquisition of knowledge as an apprenticeship, in which individuals internalize cultural concepts and skills through association with more skilled members of their group.
Key Terms: zone of proximal development, apprenticeship

A Psychometric Approach to Intelligence: Although difficult to define, most agree that intelligence allows us to profit from our experiences and adapt to our surroundings and that it typically involves abstract reasoning. Common measures of intelligence reflect the knowledge and abilities of the average person in our society. Most intelligence tests, though, reflect one’s familiarity with the culture. And while there is no gender difference in overall intelligence, several specific differences can be noted, such as females do somewhat better on measures of verbal reasoning and fluency, comprehending written passages, and understanding logical relations, and males do better on measures of spatial ability and score higher in math on standardized achievement tests such as the SAT.
Key Terms: psychometric approach, intelligence, WISC-IV, WAIS-III, culture-fair test, SAT

Sternberg’s Componential Intelligence: Sternberg analyzes intellectual functioning in terms of components, or processes that operate on information.
Key Terms: metacomponents, performance components, knowledge-acquisition components

Gardner’s multiple intelligences: Gardner defines intelligence as one’s ability to solve problems as they arise, but includes problems from a broad domain, identifying eight types of intelligence. Practical intelligence requires that we define the problem to be solved and decide what constitutes a solution.
Key Terms: multiple intelligences, practical intelligence

An Information Processing Approach: The information processing approach to cognitive development focuses on the specific processes involved in developmental change, rather than on the characteristics of any stage or thought, or on individual differences in measured intelligence. A number of processes show progressive changes with age. For instance, adolescents get more efficient, and faster, at processing information, and are better able to address multiple problems at once, and use strategies to do so.
Key Terms: information processing, automaticity, speed of processing, working memory, encoding, strategies

Implications for the Classroom

Reasoning: Using inductive reasoning, adolescents are able to reason from the particular to the general; deductive reasoning enables them to reason from the general to the particular.
Key Terms: inductive reasoning, deductive reasoning

Can Adolescents Think Like Scientists?: Adolescents are able to think scientifically by formulating a strategy that enables them to systematically approach a problem, holding all conditions constant except the one they are testing.

Study Skills and Knowing What You Don’t Know: Adolescents are able to study more effectively than younger children because they are better able to monitor their performance.

Metaphors and Meaning: When is a Ship a State?: Adolescents understand multiple levels of meaning, enabling them to understand figurative uses of language and appreciate metaphor.

Implications for Everyday Life

Adolescent Egocentrism: Adolescents frequently make problems more complex than they are and feel stupid when someone else comes up with the obvious solution. The ability of adolescents to think about thinking leads them to create an imaginary audience in which they feel themselves to be the center of everyone’s attention. The personal fable is the complement of the imaginary audience; adolescents believe they are unique and invulnerable.
Key Terms: egocentrism, imaginary audience, personal fable

Social Cognition: Understanding Others: Adolescents’ awareness of others’ thoughts contributes to social understanding that is reflected in adolescents’ ability to assume another’s perspective and coordinate this with their own. Adolescents can infer how another might be thinking and anticipate how that person will react to their reactions to them.

Doubt and Skepticism: With the knowledge that “reality” and “truth” are often just one group’s interpretation of the data comes a profound skepticism in which adolescents come to doubt the possibility of ever knowing anything for certain.

New Emotions: Intellectual development in adolescence makes it possible for teenagers to react emotionally in new ways, considering what a situation might mean as well as the way it appears.

Arguing: The ability of adolescents to consider the possibilities in any situation not only affects their emotions, but means they can argue better than children can, and can take either side of an issue, whether or not they believe in it.