Tuesday, March 13, 2012

Intelligence Testing

The first intelligence test was designed by French psychologist Alfred Binet and his colleague Theodore Simon in 1905 as a means of placing schoolchildren in the appropriate grades in public school. Since this first application to educational placement, intelligence testing has developed into a field and industry in its own right. Intelligence tests have varied in terms of their assumptions and applications.

A. Individual Tests
Most intelligence tests were originally developed to be administered to one respondent at a time, or individually.

1. The Binet-Simon Scale
Binet and Simon's original test consisted of 30 subtests involving tasks that children of different ages should be able to perform. If a child could answer the questions that the average nine-year-old could ansewer, he or she was assigned a mental age( MA) of nine.

Each child's MA, as measured by the test, was compared with his or her acutal chronological age (CA). When mental age exceeded chronological age (eg. a seven-year-old with an MA of nine) the child was classified as bright, and assigned to a higher grade level. If CA exceeded MA, the child would be assigned to a lower grade level.

2. The Intelligence Quotient
German psychologist William Stern argued that a simple comparison between MA and CA - eg. concluding that "MA > CA" - was insensitive to degrees of comparison.

Instead, Stern advocated using the ratio of MA to CA to measure intelligence. To eliminate decimal points, Stern's formula for this intelligence quotient(IQ) (since a quotient is the result of an arithmetric division) was: MA/CA x 100 = IQ. For example, a child with an MA of 9 and a CA of 6 has an IQ of 150, whereas one with an MA of 9 and a CA of 12 has an IQ of 75. When MA = CA, IQ = 100.

3. The Stanford-Binet Intelligence Scale
In 1916 (and several times since), Stanford University psychologist Lewis Terman(1877-1956) revised the original Binet-Simon scale of intelligence. Items that yielded little information were discarded, others were improved, and the resulting test, titled the Stanford-Binet Intelligence Scale, was restandardized on new populations of children.

The most recent version of the Stanford-Binet includes four designated areas, with its own set of subtests: verbal reasoning; abstract value reasoning; quantitative reasoning; and short-term memory.

4. The Wechsler Tests
The individual intelligence test most often administered today is likely to be one developed by the late American psychologist David Wechsler.

Wechsler's scale consists of two subscales: a verbal scale, and a perfomance scale. The verbal scale includes questions and tasks involving informaation, arithmetic, and comprehension. The performance scale includes tests of picture arrangement, puzzle assembly, block design assembly, and identification of elements missing in pictures.

The Wechsler Adult Intelligence Scale-Revised (WAIS-R) is administered to individuals over age 16, while the Wechsler Intelligence Test for Children -Revised (WISC-R) is administered to school-age children.

B. Group Tests
For the sake of expediency and time, many "intelligence" tests -- often tests of achievement or of a particular skill like verbal ability -- are designed to be administered in paper-and pencil form to many individuals simultaneously. Best known among high-school and college students are the Scholastic Aptitude Test (SAT) and the American College Testing (ACT) program. Group tests are convenient and eliminate examiner bias. They are usually limited in the comprehensiveness of their results in comparison with individual tests.

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