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.

Thought that arises from an emotion or a hunch, beyond rational explanation, and is influenced by past experiences and cultural assumptions.

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.

Reasoning that includes propositions and possibilities that may not reflect reality.

The mistaken belief that if money, time, or effort that cannot be recovered (a “sunk cost,” in economic terms) has already been invested in some endeavor, then more should be invested in an effort to reach the goal. Because of this fallacy, people spend money trying to fix a “lemon” of a car or send more troops to fight a losing battle.

The 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.

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.

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

A common fallacy in which a person ignores the overall frequency of some behavior or characteristic (called the base rate) in making a decision. For example, a person might bet on a “lucky” lottery number without considering the odds that that number will be selected.

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

The notion that two networks exist within the human brain, one for emotional and one for analytical processing of stimuli.

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.

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.

An international test taken by 15-year-olds in 50 nations that is designed to measure problem solving and cognition in daily life.

Literally, the period after primary education (elementary or grade school) and before tertiary education (college). It usually occurs from about ages 12 to 18, although there is some variation by school and by nation.

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

A school for children in the grades between elementary and high school. Middle school usually begins with grade 6 and ends with grade 8.

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.

Reasoning from one or more specific experiences or facts to reach (induce) a general conclusion. (Also called bottom-up reasoning.)

Bullying that occurs when one person spreads insults or rumors about another by means of emails, text messages, or cell phone videos.