Intelligence — the ability to think, to learn from experience, to solve problems, and to adapt to new situations — is more strongly related than any other individual difference variable to successful educational, occupational, economic, and social outcomes.
The French psychologist Alfred Binet and his colleague Henri Simon developed the first intelligence test in the early 1900s. Charles Spearman called the construct that the different abilities and skills measured on intelligence tests have in common the general intelligence factor, or simply “g.”
There is also evidence for specific intelligences (s), measures of specific skills in narrow domains. Robert Sternberg has proposed a triarchic (three-part) theory of intelligence, and Howard Gardner has proposed that there are eight different specific intelligences.
Good intelligence tests both are reliable and have construct validity. Intelligence tests are the most accurate of all psychological tests. IQ tests are standardized, which allows calculation of mental age and the intelligence quotient (IQ),
The Wechsler Adult lntelligence Scale (WAIS) is the most widely used intelligence test for adults. Other intelligence tests include aptitude tests such as the Graduate Record Examination (GRE), and structured tests used for personnel selection.
People with higher IQs have somewhat larger brains, which operate more efficiently and faster than the brains of the less intelligent. Although intelligence is not located in a specific part of the brain, it is more prevalent in some brain areas than others.
Intelligence has both genetic and environmental causes, and between 40% and 80% of the variability in IQ is heritable. Social and economic deprivation, including poverty, can adversely affect IQ, and intelligence is improved by education.
Emotional intelligence refers to the ability to identify, assess, manage, and control one’s emotions. However, tests of emotional intelligence are often unreliable, and emotional intelligence may be a part of a skill that can be applied in some specific work situations.
About 3% of the population score above an IQ of 130 (the threshold for giftedness), and about the same percentage score below an IQ of 70 (the threshold for mental retardation). Males are about 20% more common in these extremes than are women.
Women and men show overall equal intelligence, but there are sex differences on some types of tasks. There are also differences in which members of different racial and ethnic groups cluster along the IQ line. The causes of these differences are not completely known. These differences have at times led to malicious, misguided, and discriminatory attempts to try to correct for them, such as eugenics.
Language involves both the ability to comprehend spoken and written words and to create communication in real time when we speak or write. Language can be conceptualized in terms of sounds (phonemes), meaning (morphemes and syntax), and the environmental factors that help us understand it (contextual information).
Language is best learned during the critical period between three and seven years of age.
Broca’s area, an area of the brain in front of the left hemisphere near the motor cortex, is responsible for language production, and Wernicke’s area, an area of the brain next to the auditory cortex, is responsible for language comprehension.
Children learn language quickly and naturally, progressing through stages of babbling, first words, first sentences, and then a rapid increase in vocabulary. Children often make overextensions of concepts.
Some theories of language learning are based on principles of learning. Noam Chomsky argues that human brains contain a language acquisition device that includes a universal grammar that underlies all human language and that allows generativity. Chomsky differentiates between the deep structure and the surface structure of an idea.
Bilingualism is becoming more and more frequent in the modern world. Bilingual children may show more cognitive function and flexibility than monolingual children do.
Nonhuman animals have a wide variety of systems of communication. But efforts to teach animals to use human language have had only limited success. Although many animals communicate, none of them has a true language.