Cognition refers to all the mental activities associated with thinking, knowing, remembering, and communicating.

We use concepts, mental groupings of similar objects, events, ideas, or people, to simplify and order the world around us. We form most concepts around prototypes, or best examples of a category.

An algorithm is a methodical, logical rule or procedure (such as a step-by-step description for evacuating a building during a fire) that guarantees a solution to a problem.

A heuristic is a simpler strategy (such as running for an exit if you smell smoke) that is usually speedier than an algorithm but is also more error-prone.

Insight is not a strategy-based solution, but rather a sudden flash of inspiration (Aha!) that solves a problem.

Tendencies that work against us in problem solving include confirmation bias, which leads us to verify rather than challenge our hypotheses, and fixation, which may prevent us from taking the fresh perspective that would lead to a solution.

Intuition involves fast, automatic, unreasoned feelings and thoughts, as contrasted with explicit, conscious reasoning.

Heuristics enable snap judgments. Using the availability heuristic, we judge the likelihood of things based on how readily they come to mind.

The availability heuristic often leads us to fear the wrong things. We also fear what our ancestral history has prepared us to fear, what we cannot control, and what is immediate. We fear too little the ongoing threats that claim lives one by one, such as traffic accidents and diseases.

Overconfidence can lead us to overestimate the accuracy of our beliefs.

When a belief we have formed has been discredited, belief perseverance may cause us to cling to that belief. A remedy for belief perseverance is to consider how we might have explained an opposite result.

Framing is the way a question or statement is worded. Subtle wording differences can dramatically alter our responses.

As people gain expertise, they become skilled at making quick, shrewd judgments. Smart thinkers welcome their intuitions (which are usually adaptive), but when making complex decisions they gather as much information as possible and then take time to let their two-track mind process all available information.

Creativity, the ability to produce new and valuable ideas, requires a certain level of aptitude (ability to learn), but it is more than school smarts. Aptitude tests require convergent thinking, but creativity requires divergent thinking.

Robert Sternberg has proposed that creativity has five components: expertise; imaginative thinking skills; a venturesome personality; intrinsic motivation; and a creative environment that sparks, supports, and refines creative ideas.

Evidence from studies of various species shows that many other animals use concepts, numbers, and tools, and that they transmit learning from one generation to the next (cultural transmission). And, like humans, some other species also show insight, self-awareness, altruism, cooperation, and grief.

Language is our spoken, written, or signed words and the ways we combine them to communicate meaning. Receptive language (the ability to understand what is said to or about you) develops before productive language (the ability to produce words).

Language development’s timing varies, but all children follow the same sequence:

Childhood is a critical period for learning language. A delay in exposure until age 2 or 3 produces a rush of language. But there is no similar rush of learning in children not exposed to either a spoken or a signed language until age 7; such deprived children will never master any language.

Noam Chomsky has proposed that all human languages share a universal grammar—the basic building blocks of language—and that humans are born with a predisposition (a built-in readiness) to learn language. The particular language we learn is the result of our experience.

Two important language- and speech-processing areas are Broca’s area, a region of the frontal lobe that controls language expression, and Wernicke’s area, a region in the left temporal lobe that controls language reception.

Language processing is spread across other brain areas as well, with different neural networks handling specific linguistic subtasks.

Thinking in images can provide useful mental practice if we focus on the steps needed to reach our goal (rather than fantasize about having achieved the goal).

A number of chimpanzees and bonobos have (1) learned to communicate with humans by signing or by pushing buttons wired to a computer, (2) developed vocabularies of nearly 400 words, (3) communicated by stringing these words together, (4) taught their skills to younger animals, and (5) demonstrated some understanding of syntax. But only humans possess language—verbal or signed expressions of complex grammar.

Intelligence is the ability to learn from experience, solve problems, and use knowledge to adapt to new situations.

Charles Spearman proposed that we have one general intelligence (g) underlying all other specific mental abilities. He helped develop factor analysis, a statistical procedure that searches for clusters of related items.

Savant syndrome and abilities lost after brain injuries seem to support Howard Gardner’s view that we have multiple intelligences. He proposed eight independent intelligences: linguistic, logical-mathematical, musical, spatial, bodily-kinesthetic, intrapersonal, interpersonal, and naturalist. (He later proposed a ninth possible intelligence—existential intelligence.)

Robert Sternberg’s triarchic theory proposes three intelligence areas that predict real-world skills: analytical (academic problem solving), creative (trailblazing smarts), and practical (street smarts).

Critics note research that has confirmed a general intelligence factor, which widely predicts performance. But highly successful people also tend to be conscientious, well connected, and doggedly energetic, with both ability and motivation counting.

Emotional intelligence, which is an aspect of social intelligence, includes the abilities to perceive, understand, manage, and use emotions. Emotionally intelligent people achieve greater personal and professional success.

Intelligence tests assess a person’s mental aptitudes and compare them with those of others, using numerical scores.

Aptitude tests measure the ability to learn; achievement tests measure what we have already learned.

Alfred Binet started the modern intelligence-testing movement in France in the early 1900s, when he developed questions to help predict children’s future progress in the Paris school system. Binet hoped his test would improve children’s education but feared it might be used to label them.

During the early twentieth century, Lewis Terman of Stanford University revised Binet’s work for use in the United States (which resulted in the Stanford-Binet intelligence test). Terman’s belief in an intelligence that was fixed at birth and differed among ethnic groups realized Binet’s fears that intelligence tests would be used to limit children’s opportunities.

William Stern contributed the concept of the IQ (intelligence quotient).

The most widely used intelligence tests today are the Wechsler Adult Intelligence Scale (WAIS) and Wechsler’s tests for children. These tests differ from their predecessors in the way they offer an overall intelligence score as well as scores for verbal comprehension, perceptual organization, working memory, and processing speed.

The distribution of test scores often forms a normal (bell-shaped) curve around the central average score, with fewer and fewer scores at the extremes.

Standardization establishes a basis for meaningful score comparisons by giving a test to a representative sample of future test-takers.

Reliability is the extent to which a test yields consistent results (on two halves of the test, on alternative forms of the test, or on retesting).

Validity is the extent to which a test measures or predicts what it is supposed to. A test should have both content validity and predictive validity. (Aptitude tests have predictive validity if they can predict future achievements.)

An intelligence test score of or below 70 is one diagnostic factor in the diagnosis of intellectual disability; limited conceptual, social, and practical skills are other factors. Some people with this diagnosis may be able to live independently. One condition included in this category is Down syndrome, a developmental disorder caused by an extra copy of chromosome 21.

People at the high-intelligence extreme tend to be healthy and well-adjusted, as well as unusually successful academically.

Heritability is the portion of variation among people in a group that can be attributed to genes. Many genes contribute to intelligence; there is no known “genius” gene.

Studies of twins, family members, and adoptive parents and siblings indicate a significant hereditary contribution to intelligence scores. But these studies also provide evidence of environmental influences.

Heredity and environment interact: Our genes shape the environments that influence us.

Studies of children raised in extremely impoverished environments with minimal social interaction indicate that life experiences can significantly influence intelligence test performance. No evidence supports the idea that normal, healthy children can be molded into geniuses by growing up in an exceptionally enriched environment.

Cross-sectional studies and longitudinal studies have shown that intelligence endures. The stability of intelligence test scores increases with age, with scores very stable and predictive by early adolescence.

Crystallized intelligence, our accumulated knowledge and verbal skills, tends to increase.

Fluid intelligence, our ability to reason speedily and abstractly, declines in older adults.

Males and females tend to have the same average intelligence test scores, but they differ in some specific abilities.

Girls are better spellers, more verbally fluent, better at locating objects, better at detecting emotions, and more sensitive to touch, taste, and color.

Boys outperform girls at spatial ability and related mathematics, though in math computation and overall math performance, boys and girls hardly differ. Boys also outnumber girls at the low and high extremes of mental abilities.

Evolutionary and cultural explanations have been proposed for these gender differences.

Racial and ethnic groups differ in their average intelligence test scores. The evidence suggests that environmental differences are responsible for these group differences.

Aptitude tests aim to predict how well a test-taker will perform in a given situation. So they are necessarily “biased” in the sense that they are sensitive to performance differences caused by cultural experience.

But a test should not predict less accurately for one group than for another. In this sense, most experts consider the major aptitude tests unbiased.

Stereotype threat, a self-confirming concern that we will be judged based on a negative stereotype, affects performance on all kinds of tests.