INTELLIGENCE TESTS

INTELLIGENCE TESTS. Although the tests created specifically to gauge intelligence were introduced to the United States in the early twentieth century, their roots go back much farther, even to exams in ancient China. The American tests, however, emerged directly from the work of nineteenth-century English scientists who were laying the foundation for the field of psycho-metrics: the scientific approach to measurement of psychological characteristics.

Early European Testing and the Stanford-Binet Test

Sir Francis Galton produced the first systematic investigations of the concept of intelligence. Galton seemed uniquely qualified for this task, as he was known for collecting and quantifying massive amounts of data. Galton's statistical analyses included seemingly random and subjective assessments. Nonetheless, his groundbreaking pronouncement endures: that intelligence is a trait normally distributed among populations. A normal distribution means that most people were of average intelligence, while a minority fell above or below this middle range. Plotting this distribution resulted in the formation of the now familiar bell curve.

Reflecting popular nineteenth-century theories of evolution, including those of his cousin, Charles Darwin, Galton viewed intelligence as a single, inherited trait. His landmark 1869 publication, Hereditary Genius, established the parameters of the scientific investigation of mental processes for years to come; his understanding of intelligence as a fixed and predetermined entity would remain largely unchallenged for nearly a century.

Eager to further explore Galton's ideas, psychologist James McKeen Cattell returned from his studies in Europe to the University of Pennsylvania in the late 1880s and began his own work. Cattell's "mental tests," a term he introduced, reflected his skills at statistical analysis. Similar to Galton's, however, his tests ultimately failed to show any real correlation between scores and demonstrated achievement. Still, Cattell's work earned growing recognition and respect for the emerging field of psychology.

The earliest intelligence tests to move beyond the theoretical and into the practical realm were the work of the French researcher Alfred Binet. The passage of a 1904 law requiring that all children attend school prompted the French government to decide what to do with children who could not keep up with classroom work. Binet and his colleague, Théodore Simon, set out to devise a test as a means of identifying these students, who would then receive tutoring or be placed in alternative classes.

Binet's first test was published in 1905.Like its sub-sequent revisions, this early version asked students to demonstrate proficiency at a variety of skills. Starting with the most basic and increasing in difficulty, they were designed to measure childrens' vocabulary and their ability to understand simple concepts and identify relationships between words. An age level or "norm" was assigned to each task, based on the age at which approximately 70 percent of children could successfully complete that task. Totaling the individual scores would yield a child's "mental age." This would be subtracted from his or her chronological age; a difference of two or more indicated that a child was mentally retarded.

Binet's research differed from that of previous investigators in several important ways: test scores were meant to measure classroom performance, not innate intelligence, and they were intended to target students who could benefit by receiving extra help. Binet was one of the few who challenged popular perceptions of intelligence as an inherent and unchangeable entity.

American professor of psychology Lewis Terman set out to refine what became widely known as the Binet-Simon Scale. Named after his long and distinguished career at Stanford University, the Stanford-Binet Intelligence Test emerged as the one to which all future tests would be compared. First published in 1916, the Stanford-Binet asked students to demonstrate competency in a variety of areas, including language comprehension, eye-hand coordination, mathematical reasoning, and memory. Terman advanced the idea proposed in 1912 by German psychologist Wilhelm Stern that intelligence could more accurately be expressed as a ratio, dividing mental age by chronological age. This would be multiplied by one hundred (to avoid the use of decimals) to arrive at what Stern labeled the "mental quotient." This quickly became known as an intelligence quotient, or IQ.

This formula ultimately yielded to new methods of calculation. Still predicated on Galton's assumption that intelligence is normally distributed, tables of raw data are statistically adjusted so that the mean scores are set at 100, with the middle two-thirds of the distribution set between 85 and 115 to form the "normal" range. This scale defines those who score below 70 as mentally retarded; those with 130 or above are often labeled gifted.

Testing the Masses

The United States entry into World War I in 1917 prompted an immediate and unprecedented demand for standardized tests. The federal government sought a way to quickly and efficiently determine the abilities of large numbers of military recruits to determine appropriate assignment of duties. Robert Yerkes of Harvard and other prominent psychiatrists created a committee in response to this need. Adopting the work of Arthur Otis, whose research in this field already was underway, they quickly produced two versions of a workable test. The Army Alpha was a written exam and the Army Beta was a verbal assessment for the considerable number of men who were unable to read. The tests resulted in grades ranging from A to E. Within weeks a group of four thousand recruits completed the first trial run.

By the end of the war over 1.7 million men had taken either the Army Alpha or Beta. Based on their scores, tens of thousands of men were promoted or assigned a lower-level duty. An additional 8,000 men received discharges as a result of their poor performance. The impact of the Army testing program reached far beyond the military service. Its success convinced the nation of the usefulness of wide-scale standardized testing. The popularity of the Alpha, in particular, launched a rapidly expanding intelligence test industry. In the years immediately following the war, schoolchildren across the country began taking its numerous revisions; by 1930 over seven million American students had taken the test.

As the popularity of mass testing continued to grow, the need for individual tests as diagnostic tools remained. The Wechsler-Bellevue Intelligence Scale supplemented the Stanford-Binet in 1939.Devised by David Wechsler of Bellevue Hospital in New York City, results included both verbal and nonverbal scores. The test was named the Wechsler Scale in 1955 (WAIS), later revised to WAIS R. The expanded group of tests, including the Wechsler Intelligence Scale for Children, Revised (WISC-R), and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI), form a battery of tests that continue to be widely used. While schools no longer routinely offer individual tests specifically designed to measure intelligence, their use continues, usually as a follow-up to demonstrated academic difficulty or to determine eligibility for special programs, such as those for gifted children. Educators continue to rely on the relative ease and efficiency of administering group tests.

Although they date back to the 1917 prototype designed for military use, standardized tests at the start of the twenty-first century offer the promise of a more reliable and sophisticated means to predict future success. There are additional advantages as well: no special training is required to administer them, they can be given to large groups at once, and computers quickly and accurately generate results. The Cognitive Abilities Test (CAT) and the School and College Ability Test (SCAT) are among the more popular. Developers of these tests compare them favorably to both the Stanford-Binet and Wechsler series. Many high school students take the Scholastic Assessment Test (SAT) as part of the college application process. Its earliest version going back to 1926, the SAT is calculated to measure both verbal and mathematical ability. Proponents point to its usefulness as one indicator of future success, and claim that it counters inevitable disparities in grading practices nationwide.

Defining Intelligence: The Debate Continues

Alfred Binet rejected the idea of tests as providing a fixed label; he believed that children could indeed grow smarter. Binet's optimism notwithstanding, the history of intelligence testing in the United States reveals that early tests reflected the prejudices of the society in which they were produced. Not surprisingly, few questioned the idea that intelligence is innate and inherited. Tests made no accommodations for the disparate social and cultural backgrounds of test takers, and indeed, helped to fuel popularly held assumptions of the need to rank entire groups based on their racial or ethnic origins. They were hailed by some as a "measuring stick to organize society." Early-twentieth-century concerns about "feeblemindedness" validated the need for testing. Amidst growing concerns over an influx of immigration, tests were proposed to reduce the flow of "mental defectives" into the country. Congress, aided by the findings of prominent psychologists, passed the 1924 Immigration Act, which restricted admission for those believed to be of inferior intellect; especially targeted were Russians, Italians, Jews, and others primarily from southern and eastern Europe. Entry examinations given at Ellis Island seemingly ignored the numerous language and cultural barriers that would be readily apparent today.

While standardized tests continue to play a dominant role in American society, many critics argue that subtle inequities remain, producing results that more accurately represent the social and economic background of the test taker rather than providing a true measure of one's capabilities. The SAT and other tests, meanwhile, retain their foothold in the academic arena. The ability to "coach" students to produce greater scores has launched a multi-million-dollar mass tutoring industry. This has prompted many to further renounce their use as an "objective" means of assessment, arguing that they are more accurate indicators of students' social and economic backgrounds.

Meanwhile, biological interpretations of intelligence endure. Interrogating the degree to which race or ethnicity are determining factors, the 1994 publication of The Bell Curve: Intelligence and Class Structure in American Life, pushed the debate to new heights. While authors Richard Herrnstein and Charles Murray suggested the merits of acknowledging genetic differences, some critics immediately decried a racist agenda and uncovered studies they believed to be scientifically unsound.

Experts continue to voice disagreement over methods of measuring intelligence. At the core of the debate lie questions regarding the very concept of intelligence itself. Some embrace interpretations that echo the theories of turn-of-the-twentieth-century psychologist Charles Spearman of England, who pointed to a single, overarching general intelligence, or "g" factor. At the other extreme is the more recent twentieth-century model created by J. P. Guilford of the University of Southern California, who has identified no less than 150 components of intelligence. Arguably the most detailed model, it has had limited impact on the field of testing; many have adopted his claim, however, that intelligence is comprised of multiple parts.

The psychologist Robert Sternberg believes that the logical or analytical reasoning that most intelligence tests measure is only one of several factors. He had added to this two other areas of assessment—practical intelligence, or the ability to cope amidst one's environment, and experiential intelligence, or propensity for insight and creativity —to form his triarchic theory of intelligence. Sternberg's theory has advanced the notion that psychological assessments move beyond the written test toward those that seek measures of practical knowledge that guide our day-to-day experiences. Also believing that traditional IQ tests ignore critical components of intelligence, Howard Garner has introduced what he calls "multiple intelligences," which range from musical ability to self-awareness. Not surprisingly, Gardner is among those who advocate more expansive interpretations of intelligence, suggesting decreased reliance on the standardized tests of the past and more emphasis on real-life performance.

Experts continue to explore the concept of intelligence. New lines of inquiry widen the scope of investigation and questions abound. Should traits of character and morality be examined? Should the ability to form emotional bonds and display musical talent be considered? Will more comprehensive approaches replace short-answer tests? And does the ability to determine one's IQ necessarily define how this score should be used? Studies are moving beyond the realm of psychological inquiry. Increasingly sophisticated ways of measuring brain activity suggest new modes of interpretation while technological advances have produced an "artificial intelligence" that previous generations of researchers could barely imagine. While we may be no closer to finding a universally accepted definition of intelligence, clearly the quest to do so remains.

BIBLIOGRAPHY

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Christine ClarkZemla

See alsoEducation ; Racial Science .

Intelligence Testing

Treatments of modern measures of intelligence often begin with a discussion of the French psychologist Alfred Binet (1857–1911). In 1905, Binet initiated the applied mental measurement movement when he introduced the first intelligence test. In response to a turn-of-the-century law in France requiring that children of subnormal mental ability be placed in special programs (rather than be expelled from school), Binet was called upon to design a test that could identify these children. Binet's first test consisted of thirty items, most of which required some degree of comprehension and reasoning. For example, one task required children to take sentences in which words were missing and supply the missing words that made sense in context (such sentence-completion tasks are still used widely). Binet grouped his test items such that the typical child of a given age group was able to answer fifty percent of the questions correctly. Individuals of similar chronological age (CA) varied widely in their scale scores, or mental age (MA). The ratio of MA to CA determined one's level of mental development; this ratio was later multiplied by 100 to calculate what is now known as the intelligence quotient (IQ).

Binet's approach was successful: children's scores on his test forecasted teacher ratings and school performance. While Binet was developing this first test of general intellectual functioning, the English psychologist Charles Spearman (1863–1945) was conducting research to identify the dominant dimension responsible for the validity of the test's predictions.

The Hierarchical Organization of Mental Abilities

Spearman was the first to propose and offer tangible support for the idea that a psychologically cohesive dimension of general intelligence, g, underlies performance on any set of items demanding mental effort. Spearman showed that g appears to run through all heterogeneous collections of intellectual tasks and test items. He demonstrated that when heterogeneous items are all lightly positively correlated and then summed, the signal carried by each is successively amplified and the noise carried by each is successively attenuated.

Modern versions of intelligence tests index essentially the same construct that was uncovered at the turn of the twentieth century by Spearman, but with much more efficiency. For example, g is a statistical distillate that represents approximately half of what is common among the thirteen subtests comprising the Wechsler Adult Intelligence Scale. As noted by intelligence researcher Ian J. Deary, the attribute g represents the research finding that "there is something shared by all the tests in terms of people's tendencies to do well, modestly, or poorly on all of them." This "tendency" is quite stable over time. In 2001, Deary's team published a study that was the longest temporal stability assessment of general intelligence, testing subjects at the age of eleven and a second time at the age of seventy-seven. They observed a correlation of 0.62, which rose to over 0.70 when statistical artifacts were controlled.

Psychometricians have come to a consensus that mental abilities follow a hierarchical structure, with g at the top of the hierarchy and other broad groups of mental abilities offering psychological import beyond g. Specifically, mathematical, spatial-mechanical, and verbal reasoning abilities all have demonstrated incremental (additional) validity beyond g in forecasting educational and vocational outcomes.

g and the Prediction of Life Outcomes

Research on general intelligence has confirmed the validity of g for forecasting educational and occupational achievement. Empiricism also has documented general intelligence's network of relationships with other socially important outcomes, such as aggression, crime, and poverty. General intellectual ability covaries 0.70–0.80 with academic achievement measures, 0.40–0.70 with military training assignments, 0.20–0.60 with work performance (higher correlations reflect greater job complexity), 0.30–0.40 with income, and around 0.20 with obedience to the law. Measures of g also correlate positively with altruism, sense of humor, practical knowledge, social skills, and supermarket shopping ability, and correlate negatively with impulsivity, accident-proneness, delinquency, smoking, and racial prejudice. This diverse family of correlates reveals how individual differences in general intelligence influence other personal characteristics.

Experts' definitions of general intelligence fit with g 's nexus of empirical relationships. Most measurement experts agree that measures of general intelligence assess individual differences pertaining to abstract thinking or reasoning, the capacity to acquire knowledge, and problem-solving ability. Traditional measures of general intelligence and standard academic achievement tests both assess these general information-processing capacities. In 1976, educational psychologist Lee Cronbach noted: "In public controversies about tests, disputants have failed to recognize that virtually every bit of evidence obtained with IQs would be approximately duplicated if the same study were carried out with a comprehensive measure of achievement" (1976, p. 211, emphasis in original).

The Causes of Individual Differences in Intelligence

Both genetic and environmental factors contribute to the individual differences observed in intelligence. The degree to which individual differences in intelligence are genetically influenced is represented by an estimate of heritability, the proportion of observed variation in intelligence among individuals that is attributable to genetic differences among the individuals. By pooling various family studies of g (e.g., identical and fraternal twins reared together or apart), the heritability of general intelligence in industrialized nations has been estimated to be approximately 40 percent in childhood and between 60 and 80 percent in adulthood. This pattern is thought to reflect the tendency of individuals, as they grow older and more autonomous, to increasingly self-select into environments congruent with their unique abilities and interests.

Environmental contributions to individual differences in intelligence are broadly defined as all non-genetic influences. Shared environmental factors, such as socioeconomic status and neighborhood context, are those that are shared by individuals within a given family but differ across families; non-shared environmental factors, such as the mentoring of a special teacher or one's peer group, are those that are generally unique to each individual within a family. The majority of environmental influences on intelligence can be attributable to non-shared factors for which the specifics, thus far, are not well known. Family studies of intelligence have consistently documented that the modest importance of shared environmental influences in early childhood, approximately 30 percent, decreases to essentially zero by adulthood.

The Debate over Research on Intelligence

The above empiricism is widely accepted among experts in the fields of measurement and individual differences. Yet research pertaining to general intelligence invariably generates controversy. Because psychological assessments are frequently used for allocating educational and vocational opportunities, and because different demographic groups (such as those based on socioeconomic status or race) differ in test scores and criterion performance, social concerns have accompanied intellectual assessment since its beginning. Because of these social concerns, alternative conceptualizations of intelligence, such as Howard Gardner's theory of multiple intelligences and Robert Sternberg's triarchic theory of intelligence, have generally been received positively by the public. Measures of these alternative formulations of intelligence, however, have not demonstrated incremental validity beyond what is already gained by conventional measures of intelligence. That is, they have not been shown to account for any more variance in important life outcomes (such as academic achievement and job performance) than that already accounted for by conventional intelligence tests.

See also: Age and Development; IQ; Retardation; Special Education.

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April Bleske-Rechek

IQ

IQ, or intelligence quotient, is a measure of intelligence that schools, children's homes, and other child-saving institutions have used since the 1910s to assess the intelligence of children for various diagnostic purposes. Welcomed and reviled in different social and political contexts in the twentieth century, especially in the United States, because its deployment has influenced the life chances of millions of children, the IQ and the tests that produce it had modest beginnings. French psychologist Alfred Binet devised the first test of intelligence for school children in 1908 and 1911. He understood that intellectual capacity increased as children matured; his age scale, which he obtained as a norm of right over wrong answers about everyday artifacts and information for each year of childhood, was based on the Gaussian bell-shaped curve. The result gave the child's "mental age." If the child was three years old and her or his mental age was normal for a three year old, then the child was normal because his or her chronological and mental ages were the same. If the child's mental age was "higher" than her or his chronological age, then the child was advanced, or had a higher than normal IQ. If the situation were reversed, then the child was behind or retarded, with a lower than normal IQ for his or her age. There were several tests for each age, and Binet expressed scores as mental ages. His great insight was that mental age existed apart from, but was related to, chronological age. William Stern, of Hamburg University, devised the notion of the intelligence quotient–soon dubbed the IQ – by dividing the child's mental age by her or his chronological age. Thus a child of ten with a mental age of twelve would have an IQ of 120. One with a chronological age of five and a mental age of four would have an IQ of only 80, and so on.

The American psychologist Lewis M. Terman, of Stanford University, "Americanized" the Binet test, and Stern's notion of the IQ, in the 1910s. He standardized the Binet test on many small town, middle-class California school children of northwestern European, Protestant extraction, so that the norms for each age were synchronized with cultural knowledge best understood by such children–and their relatives, peers, and neighbors. In transforming Binet's test into the Stanford-Binet measuring scale of intelligence, or, more simply, the Stanford-Binet, Terman insisted that the test measured innate intelligence in individuals and in groups, and this assumption was not widely or seriously questioned by mainstream academic psychologists until the 1960s. The Stanford-Binet became the model for subsequent IQ tests and tests of intelligence, in the United States for the next generation, thus influencing the lives of many children in America and abroad. From the 1920s to the 1960s, the IQ reigned supreme in education and social welfare institutions. Although it is true that in the 1920s there was a furious, if short-lived, controversy among social scientists over whether such tests constituted legitimate scientific measures of the "average IQ" of specific ethnic and racial groups in the population, only an ignored handful of researchers questioned whether an individual's IQ was innate at birth and stable thereafter.

After the 1960s, various constituencies and interest groups raised critical questions about IQ testing. Champions of civil rights and feminism claimed that defenders of segregation and institutionalized racism had used so-called average racial IQ scores to keep minorities and females from good schools, jobs, and neighborhoods. Some psychologists claimed that intelligence was too complex a phenomenon to be reduced to a simple ratio; most post–World War II tests, based on a model developed by the psychologist David Wechsler, argued that intelligence was the consequence of multiple factors and processes. Researchers in early childhood education insisted in the 1960s that IQs of preschool age children could and did respond to environmental stimuli and pressures by at least as much as the gap between many racial minorities and the white majority. As in the 1920s, a nature versus nurture debate took place over the next several decades without a definite conclusion. After World War II, most institutions, such as schools and child-saving organizations, tended to interpret IQ scores as mere indicators, to be used with many other indices to understand a child and her or his potentiality.

See also: Child Development, History of the Concept of; Intelligence Testing.

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Hamilton Cravens

IQ (intelligence quotient) Classification of the supposed intelligence of a person. It is computed by dividing the person's assessed ‘mental age’ by their real age, then multiplying by 100. The ‘mental age’ is determined by comparison to the average performance of people of various ages on a standard intelligence test. See also aptitude test

intelligence quotient (IQ) (in-tel-i-jĕns kwoh-shĕnt) n. an index of intellectual development. In childhood and adult life it represents intellectual ability relative to the rest of the population; in children it can also represent rate of development (mental age as a percentage of chronological age).

in·tel·li·gence quo·tient (abbr.: IQ) • n. a number representing a person's reasoning ability (measured using problem-solving tests) as compared to the statistical norm or average for their age, taken as 100.

intelligence quotient a number representing a person's reasoning ability (measured using problem-solving tests) as compared to the statistical norm or average for their age, taken as 100. Abbreviated as IQ.

IQ • abbr. intelligence quotient.

IQ n. see intelligence quotient.

intelligence quotient See IQ