Intelligence and Intelligence Testing - 9 Cognition - STEP 4 Review the Knowledge You Need to Score High

5 Steps to a 5: AP Psychology - McGraw Hill 2021

Intelligence and Intelligence Testing
9 Cognition
STEP 4 Review the Knowledge You Need to Score High

Since intelligence is a construct, it can only be defined by the behaviors that indicate intelligence, such as the ability to learn from experience, solve problems, use information to adapt to the environment, and benefit from training. Because intelligence tests are common and have been used so widely, they have influenced the definition of intelligence; sometimes a score is used to define someone’s intelligence. Intelligence is sometimes reified. Reification occurs when a construct is treated as though it were a concrete, tangible object. Intelligence test developer David Wechsler said, “Intelligence, operationally defined, is the aggregate or global capacity of the individual to act purposefully, to think rationally, and to deal effectively with his environment.”

Francis Galton’s Measurement of Psychophysical Performance

Modern ability testing originated with Charles Darwin’s cousin, nativist Francis Galton, who measured psychomotor tasks to gauge intelligence, reasoning that people with excellent physical abilities are better adapted for survival and thus highly intelligent. James McKeen Cattell brought Galton’s studies to the United States, measuring strength, reaction time, sensitivity to pain, and weight discrimination, using the term mental test. Although Galton and Cattell’s measurements correlated poorly with reasoning ability, they drew attention to the systematic study of measuring cognitive and behavioral differences among individuals. At about the same time, French psychologist Alfred Binet was hired by the French government to identify children who would not benefit from a traditional school setting and those who would benefit from special education. He thought intelligence could be measured by sampling performance of tasks that involved memory, comprehension, and judgment. He collaborated with Theodore Simon to create the Binet—Simon scale, which he meant to be used only for class placement.

Alfred Binet’s Measurement of Judgment

Binet thought that as we age, we become more sophisticated in the ways we know about the world and that, therefore, most 6-year-olds answer questions differently than 8-year-olds do. As a result of their responses to test items, children were assigned a mental age or mental level reflecting the age at which typical children give those same responses. Although mental age differentiates between abilities of children, it can be misleading when a 6-year-old and an 8-year-old, for example, have mental ages 2 years below their actual (chronological) ages. The younger child would be proportionally further behind peers than the older child. German psychologist William Stern suggested using the ratio of mental age (MA) to chronological age (CA) to determine the child’s level of intelligence.

Mental Age and the Intelligence Quotient

In adapting Binet’s test for Americans, Lewis Terman developed the Stanford-Binet Intelligence Scale reporting results as an IQ, intelligence quotient, which is the child’s mental age divided by his or her chronological age, multiplied by 100; or MA/CA × 100. A 10-year-old who answers questions typical of most 12-year-olds has an IQ score of 120. Another 10-year-old who answers questions typical of an 8-year-old scores 80. With the development of intelligence tests for adults, the ratio IQ becomes meaningless and has been replaced by the deviation IQ determined as a result of the standardizing process for a particular test. For the fifth edition of the Stanford-Binet Intelligence Scale for Adults, the test has been standardized with a representative sample of test takers up to age 90. Fluid reasoning, visual-spatial processing, working memory, and quantitative reasoning seem to peak in the 30s, whereas knowledge seems to peak in the 50s.

The newest version assesses each of five ability areas, such as knowledge, fluid reasoning, and quantitative reasoning, both nonverbally and verbally. By combining these subtest scores, one IQ score is determined.

The Wechsler Intelligence Scales

David Wechsler developed another set of age-based intelligence tests: the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) for preschool children, the Wechsler Intelligence Scale for Children (WISC) for ages 6 to 16, and the Wechsler Adult Intelligence Scale (WAIS ) for older adolescents and adults. The latest edition, the WAIS-III, has a verbal scale including items on comprehension, vocabulary, information, similarities, arithmetic, and digit span and a performance scale including items dealing with object assembly, block design, picture completion, picture arrangement, and digit symbols. Wechsler based his measures on deviation IQs or how spread out the scores were from the mean of 100 (Figure 9.2). Since intelligence has a bell curve distribution, 68 percent of the population will have an IQ between 85 and 115. These test takers are considered to be low normal through high normal. Test takers who fall two deviations below the mean have a score of 70, typically considered the borderline for intellectual disability, while test takers two standard deviations above the mean have scores of 130, sometimes considered intellectually gifted, and those three standard deviations above the mean have scores of 145, sometimes considered geniuses. The Wechsler tests are judged more helpful for determining the extremes of intelligence at the intellectual disability and the genius level than the Stanford—Binet. They also help indicate possible learning disabilities when a child’s performance IQ is very different from his or her verbal score.


Figure 9.2 The normal curve.

Intellectual Disability

Over the past two decades, the term mental retardation has been replaced by intellectual disability (intellectual developmental disorder). To be considered intellectually disabled, an individual must earn a score at or below 70 on an IQ test and also show difficulty adapting in everyday life. Adaptive behavior is expressed in conceptual skills, social skills, and practical skills. Severity is determined by adaptive functioning rather than IQ score. Typically individuals with mild intellectual disability (about 85 percent) can care for themselves, can care for a home, achieve a sixth-grade education, hold a job, get married, and become an adequate parent. In schools, they are often mainstreamed, or integrated into regular education classes.

Individuals with moderate intellectual disability (about 10 percent) may achieve a second-grade education; may be given training in skills such as eating, toileting, hygiene, dressing, and grooming so that they can care for themselves; and may be given basic training in home management, consumer, and community mobility skills so that they can hold menial jobs and live successfully in a group home. Individuals with severe intellectual disability (about 5 percent) typically develop a very limited vocabulary and learn limited self-care skills. Usually they are unable to care for themselves adequately and do not develop enduring friendships. Individuals with profound intellectual disability (1—2 percent) require custodial care. Communities have been housing a greater proportion of cognitively disabled people than in the past. These people live with their own families or in group homes when possible. This deinstitutionalization is termed normalization.

Kinds of Intelligence

Is there one underlying capacity for intelligence, or do we have different, distinct ways of being intelligent? A contemporary of Alfred Binet, Charles Spearman, tested a large number of people on a number of different types of mental tasks. He used factor analysis, a statistical procedure that identifies closely related clusters of factors among groups of items by determining which variables have a high degree of correlation. Because all the mental tasks had a high degree of correlation, he concluded that one important factor, which he called g, underlies all intelligence. Because the correlation wasn’t a perfect 1.0 between all pairs of factors, he also concluded the existence of the less important s, or specialized abilities. Louis Thurstone disagreed with Spearman’s concept of g. Based on factor analysis of tests of college students, Thurstone identified seven distinct factors he called primary mental abilities, including inductive reasoning, word fluency, perceptual speed, verbal comprehension, spatial visualization, numerical ability, and associative memory. J. P. Guilford divided intelligence into 150 different intelligence sets.

John Horn and Raymond Cattell determined that Spearman’s g should be divided into two factors of intelligences: fluid intelligence, those cognitive abilities requiring speed or rapid learning that tend to diminish with adult aging, and crystallized intelligence, learned knowledge and skills such as vocabulary that tend to increase with age.

Multiple Intelligences

Howard Gardner is one of the many critics of the g or single factor intelligence theory. Savants, individuals otherwise considered mentally retarded, have a specific exceptional skill, typically in calculating, music, or art. To Howard Gardner, this is one indication that a single factor g does not underlie all intelligence. He has proposed a theory of multiple intelligences. Three of his intelligences are measured on traditional intelligence tests: logical-mathematical, verbal-linguistic, and spatial. Five of his intelligences are not usually tested on standardized tests: musical, bodily-kinesthetic, naturalistic, intrapersonal, and interpersonal. Gardner has also introduced the possibility of a ninth intelligence—existential—which would be seen in those who ask questions about our existence, life, death, and how we got here. According to Gardner, these abilities also represent ways that people process information differently in the world, which has led to changes in how some school systems classify gifted and talented children for special programs. Peter Salovey and John Mayer labeled the ability to perceive, express, understand, and regulate emotions as emotional intelligence.

Salovey and Mayer’s emotional intelligence combines Gardner’s intrapersonal and interpersonal intelligences. Salovey, Mayer, and David Caruso developed the Multifactor Emotional Intelligence Scale (MEIS) to measure emotional intelligence. The items test the test taker’s ability to perceive, understand, and regulate emotions.

Robert Sternberg also believes that intelligence is more than what is typically measured by traditional IQ tests and has described three distinct types of intelligence in his triarchic theory of intelligence: analytic, creative, and practical. Analytical thinking is what is tested by traditional IQ test and what we are asked to do in school—compare, contrast, analyze, and figure out cause and effect relationships. Creative intelligence is evidenced by adaptive reactions to novel situations, showing insight, and being able to see more than one way to solve a problem. Practical intelligence is what some people consider “street smarts.” This would include the ability to read people, knowing how to put together a bake sale, or being able to get to a distant location. Whether it is labeled as emotional intelligence, interpersonal intelligence, or practical intelligence, such emotionally smart people can often succeed in careers, marriages, and parenting where people with higher IQ scores, but less emotional intelligence, fail.


Creativity, the ability to generate ideas and solutions that are original, novel, and useful, is not usually measured by intelligence tests. According to the threshold theory, a certain level of intelligence is necessary, but not sufficient for creative work. Although many tests of creativity have been developed, such as the Torrance Test of Creative Thinking, the Christensen-Guilford Test, the Remote Associates Test, and the Wallach and Kogan Creative Battery, they do not have high criterion-related validity.

Because tests are used to make decisions, these are criticized for their shortcomings. Although psychometricians, other psychologists, educators, and ethicists agree that intelligence tests measure the ability to take tests well, they do not agree that intelligence tests actually measure intelligence. Since results of intelligence tests correlate highly with academic achievement, they do have predictive validity.