Intelligence Assessment (General)

Introduction

The assessment of intelligence via the conventional IQ test has tremendous potential for great use and great abuse. IQ tests can be used to categorize people into oblivion and misinterpreted to support a wide variety of racist and sexist ideologies. But they can also be used to examine and treat children once simply called ‘stupid’. This entry will briefly touch on the history of intelligence assessment and then focus on the Wechsler Scales, the most-used tests of cognitive development, the Stanford-Binet IV, the descendant of the first major test of cognitive development, and then describe more recent tests of cognitive development, such as the Kaufman tests, the Woodcock-Johnson, the Differential Ability Scales, and the Cognitive Assessment System. Although theory played little or no role in the original Stanford-Binet and the Wechsler scales, the more recent tests have generally been theory-driven with Horn's model of intelligence (1989) and Luria's (1980) neuropsychological approach being the most influential. The uses for IQ tests in contemporary society are decidedly practical: identification (of mental retardation, learning disabilities, other cognitive disorders, giftedness), placement (gifted and other specialized programmes), and as a cognitive adjunct to a clinical evaluation whose main focus is on personality or neuropsychological evaluation. Yet, the introduction of theory into test development (e.g. Kaufman & Kaufman, 1983; Woodcock & Johnson, 1989) and test interpretation (Kaufman, 1994) has provided an important foundation for helping examiners optimize these practical applications of IQ tests.

History of Intelligence Assessment

The assessment of intelligence was conceived in a theoretical void and born into a theoretical vacuum. During the last half of the nineteenth century, first Sir Francis Galton in England (1883) and then Alfred Binet in France (Binet & Henri, 1895) took turns in developing the leading intelligence tests of the day. Galton, who was interested in men of genius and in eugenics, developed his test from a vague, simplistic theory that people take in information through their senses, so the most intelligent people must have the best developed senses. His test included a series of sensory, motor, and reaction-time tasks, all of which produced reliable, consistent results (Galton, the half-cousin of Charles Darwin, was strictly a scientist, and accuracy was essential), but none of which proved to be valid as measures of the construct of intelligence (Kaufman, 2000). Alfred Binet, with the assistance of the Minister of Public Instruction in Paris (who was eager to separate mentally retarded from normal children in the classroom), published the first ‘real’ intelligence test in 1905. Like Galton's test, Binet's instrument had only a vague tie to theory (in this case, the notion that intelligence was a single, global ability that people possessed in different amounts). In a stance antithetical to Galton's, Binet declared that because intelligence [Page 466]is complex, so, too, must be its measurement. He conceptualized intelligence as one's ability to demonstrate memory, judgement, reasoning, and social comprehension, and he and his colleagues developed tasks to measure these aspects of global intelligence. Binet's contributions included his focus on language abilities (rather than the non-verbal skills measured by Galton) and his introduction of the mental age concept, derived from his use of age levels, ranging from 3 to 13 years, in his revised 1908 scale (mental age was the highest age level at which the child had success; the Intelligence Quotient, or IQ, became the ratio of the child's mental age to chronological age, multiplied by 100). In 1916, Lewis Terman of Stanford University translated and adapted the Binet-Simon scales in the US to produce the Stanford-Binet (Terman, 1916).

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