9.7 SUMMARY

• Human language is organized at several levels, from phonemes to morphemes to phrases and finally to sentences.
• Grammatical rules are acquired early in development, even without being taught explicitly. Instead, children appear to be biologically predisposed to process language in ways that allow them to extract these grammatical rules from the language they hear.
• In the brain, Broca’s area is critical for language production and Wernicke’s area is critical for language comprehension.
• Some bilingual children show greater executive control capacities, such as the ability to prioritize information and flexibly focus attention.

• We organize knowledge about objects, events, or other stimuli by creating concepts, prototypes, and exemplars.
• Family resemblance theory states that items in the same category share certain, if not all, features; prototype theory states that we use the most typical member of a category to assess new items; exemplar theory states that we compare new items with stored memories of other members of the category.
• Neuroimaging studies have shown that prototypes and exemplars are processed in different parts of the brain and that the brain may be “prewired” to respond strongly to distinct categories, such as living things and human-made things.

• Human decision making often departs from a completely rational process, and the mistakes that accompany this departure tell us a lot about how the human mind works.
• We can make irrational decisions when we fail to estimate probabilities accurately or when we fall prey to the availability bias, the conjunction fallacy, the representativeness heuristic, or framing effects.
• The prefrontal cortex plays an important role in decision making, and patients with prefrontal damage make more risky decisions than do healthy individuals.

• Intelligence is a mental ability that enables people to direct their thinking, adapt to their circumstances, and learn from their experiences.
• Intelligence tests produce a score known as an intelligence quotient or IQ. Ratio IQ is the ratio of a person’s mental to physical age, and deviation IQ is the deviation of a person’s test score from the average score of his or her peers.
• Intelligence test scores predict a variety of important life outcomes, such as scholastic performance, job performance, health, and wealth.
• People who score well on one test of mental ability usually score well on others, which suggests that there is a property called g (general intelligence), but they don’t always score well on others, which suggests that there are also properties called s (specific abilities). Research reveals that between g and s are several middle-level abilities.

• Both genes and environments influence intelligence.
• Relative intelligence is generally stable over time, but absolute intelligence changes.
• SES has a powerful influence on intelligence, and education has a moderate influence.

• Some groups outscore others on intelligence tests because (a) testing situations impair the performance of some groups more than others, and (b) some groups live in less healthful and stimulating environments.
• There is no compelling evidence to suggest that between-group differences in intelligence are due to genetic differences.
• Human intelligence can be temporarily increased by cognitive enhancers such as Ritalin and Adderall, and nonhuman intelligence has been permanently increased by genetic manipulation.