Psychology Intelligence Introduction, Theories & Intelligence Testing
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Introduction
Few people agree on exactly what “intelligence” is or how to measure it. The nature and origin of intelligence are elusive, and the value and accuracy of intelligence tests are often uncertain. Researchers who study intelligence often argue about what IQ tests really measure and whether or not Einstein’s theories and Yo Yo Ma’s cello playing show different types of intelligence.
Intelligence is a particularly thorny subject, since research in the field has the potential to affect many social and political decisions, such as how much funding the U.S. government should devote to educational programs. People who believe that intelligence is mainly inherited don’t see the usefulness in special educational opportunities for the underprivileged, while people who believe that environment plays a large role in intelligence tend to support such programs. The importance and effects of intelligence are clear, but intelligence does not lend itself to easy definition or explanation.
Theories of Intelligence
A typical dictionary definition of intelligence is “the capacity to acquire and apply knowledge.” Intelligence includes the ability to benefit from past experience, act purposefully, solve problems, and adapt to new situations. Intelligence can also be defined as “the ability that intelligence tests measure.” There is a long history of disagreement about what actually constitutes intelligence.
Savant Syndrome
Savant syndrome, observed in some individuals diagnosed with autism or mental retardation, is characterized by exceptional talent in one area of functioning, such as music or math, and poor mental functioning in all other areas.
The G Factor
Charles Spearman proposed a general intelligence factor, g, which underlies all intelligent behavior. Many scientists still believe in a general intelligence factor that underlies the specific abilities that intelligence tests measure. Other scientists are skeptical, because people can score high on one specific ability but show weakness in others.
Eight Types of Intelligence
In the 1980s and 1990s, psychologist Howard Gardner proposed the idea of not one kind of intelligence but eight, which are relatively independent of one another. These eight types of intelligence are:
- Linguistic: spoken and written language skills
- Logical–mathematical: number skills
- Musical: performance or composition skills
- Spatial: ability to evaluate and analyze the visual world
- Bodily-kinesthetic: dance or athletic abilities
- Interpersonal: skill in understanding and relating to others
- Intrapersonal: skill in understanding the self
- Nature: skill in understanding the natural world
Gardner believes that each of these domains of intelligence has inherent value but that culture and context may cause some domains to be emphasized over others. Critics of the idea of multiple intelligences maintain that these abilities are talents rather than kinds of intelligence.
Triarchic Theory of Intelligence
Also in the 1980s and 1990s, Robert Sternberg proposed a triarchic theory of intelligence that distinguishes among three aspects of intelligence:
- Componential intelligence: the ability assessed by intelligence tests
- Experiential intelligence: the ability to adapt to new situations and produce new ideas
- Contextual intelligence: the ability to function effectively in daily situations
Emotional Intelligence
Some researchers distinguish emotional intelligence as an ability that helps people to perceive, express, understand, and regulate emotions. Other researchers maintain that this ability is a collection of personality traits such as empathy and extroversion, rather than a kind of intelligence.
Intelligence Testing
The psychometric approach to intelligence emphasizes people’s performance on standardized aptitude tests. Aptitude tests predict people’s future ability to acquire skills or knowledge. Achievement tests, on the other hand, measure skills and knowledge that people have already learned.
Types of Tests
Intelligence tests can be given individually or to groups of people. The best-known individual intelligence tests are the Binet-Simon scale, the Stanford-Binet Intelligence Scale, and the Wechsler Adult Intelligence Scale.
The Binet-Simon Scale
Alfred Binet and his colleague Theodore Simon devised this general test of mental ability in 1905, and it was revised in 1908 and 1911. The test yielded scores in terms of mental age. Mental age is the chronological age that typically corresponds to a particular level of performance.
Example: A ten-year-old child whose score indicates a mental age of twelve performed like a typical twelve-year-old.
The Stanford-Binet Intelligence Scale
In 1916, Lewis Terman and his colleagues at Stanford University created the Stanford-Binet Intelligence Scale by expanding and revising the Binet-Simon scale. The Stanford-Binet yielded scores in terms of intelligence quotients. The intelligence quotient (IQ) is the mental age divided by the chronological age and multiplied by 100. IQ scores allowed children of different ages to be compared.
Example: A ten-year-old whose performance resembles that of a typical twelve-year-old has an IQ of 120 (12 divided by 10 times 100).
There are two problems with the intelligence quotient approach:
- The score necessary to be in the top range of a particular age group varies, depending on age.
- The scoring system had no meaning for adults. For example, a fifty-year-old man who scores like a thirty-year-old can’t accurately be said to have low intelligence.
The Stanford-Binet was revised in 1937, 1960, 1973, and 1986.
Wechsler Adult Intelligence Scale
David Wechsler published the first test for assessing intelligence in adults in 1939. The Wechsler Adult Intelligence Scale contains many items that assess nonverbal reasoning ability and therefore depends less on verbal ability that does the Stanford-Binet. It also provides separate scores of verbal intelligence and nonverbal or performance intelligence, as well as a score that indicates overall intelligence.
The term intelligence quotient, or IQ, is also used to describe the score on the Wechsler test. However, the Wechsler test presented scores based on a normal distribution of data rather than the intelligence quotient. The normal distribution is a symmetrical bell-shaped curve that represents how characteristics like IQ are distributed in a large population. In this scoring system, the mean IQ score is set at 100, and the standard deviation is set at 15. The test is constructed so that about two-thirds of people tested (68 percent) will score within one standard deviation of the mean, or between 85 and 115.
On the Wechsler test, the IQ score reflects where a person falls in the normal distribution of IQ scores. Therefore, this score, like the original Stanford-Binet IQ score, is a relative score, indicating how the test taker’s score compares to the scores of other people. Most current intelligence tests, including the revised versions of the Stanford-Binet, now have scoring systems based on the normal distribution. About 95 percent of the population will score between 70 and 130 (within two standard deviations from the mean), and about 99.7 percent of the population will score between 55 and 145 (within three standard deviations from the mean).
Group Intelligence Tests
Individual intelligence tests can be given only by specially trained psychologists. Such tests are expensive and time-consuming to administer, and so educational institutions often use tests that can be given to a group of people at the same time. Commonly used group intelligence tests include the Otis-Lennon School Ability Test and the Lorge-Thorndike Intelligence Test.
Biological Tests of Intelligence
Some researchers have suggested that biological indices such as reaction time and perceptual speed relate to intelligence as measured by IQ tests:
- Reaction time: the amount of time a subject takes to respond to a stimulus, such as by pushing a button when a light is presented.
- Perceptual speed: the amount of time a person takes to accurately perceive and discriminate between stimuli. For example, a test of perceptual speed might require a person to determine which of two lines is shorter when pairs of lines flash very briefly on a screen.
The Influence of Culture
Many psychologists believe that cultural bias can affect intelligence tests, for the following reasons:
- Tests that are constructed primarily by white, middle-class researchers may not be equally relevant to people of all ethnic groups and economic classes.
- Cultural values and experiences can affect factors such as attitude toward exams, degree of comfort in the test setting, motivation, competitiveness, rapport with the test administrator, and comfort with problem solving independently rather than as part of a team effort.
- Cultural stereotypes can affect the motivation to perform well on tests.
Characteristics of IQ Tests
Some characteristics of IQ tests are standardization, norms, percentile scores, standardization samples, reliability, and validity.
Standardization
Intelligence tests are standardized, which means that uniform procedures are used when administering and scoring the tests. Standardization helps to ensure that people taking a particular test all do so under the same conditions. Standardization also allows test takers to be compared, since it increases the likelihood that any difference in scores between test-takers is due to ability rather than the testing environment. The SAT and ACT are two examples of standardized tests.
Norms and Percentile Scores
Researchers use norms when scoring the tests. Norms provide information about how a person’s test score compares with the scores of other test takers. Norms allow raw test scores to be converted into percentile scores. A percentile score indicates the percentage of people who achieved the same as or less than a particular score. For example, if someone answered twenty items correctly on a thirty-item vocabulary test, he receives a raw score of 20. He consults the test norms and finds that a raw score of 20 corresponds with a percentile score of 90. This means that he scored the same as or higher than 90 percent of people who took the same test.
Standardization Samples
Psychologists come up with norms by giving a test to a standardization sample. A standardization sample is a large group of people that is representative of the entire population of potential test takers.
Reliability
Most intelligence tests have good reliability. Reliability is a test’s ability to yield the same results when the test is administered at different times to the same group of people. For more on reliability, see page 14.
Validity
Validity is a test’s ability to measure what it is supposed to measure. For more on validity, see page 14. Although intelligence tests cannot be considered good measures of general intelligence or general mental ability, they are reasonably valid indicators of the type of intelligence that enables good academic performance.
Critical Views on Intelligence Testing
Critics of widespread intelligence testing point out that politicians and the public in general misuse and misunderstand intelligence tests. They argue that these tests provide no information about how people go about solving problems. Also, say the critics, these tests do not explain why people with low intelligence scores can function intelligently in real-life situations. Advocates of intelligence testing point out that such tests can identify children who need special help, as well as gifted children who can benefit from opportunities for success.
