Intelligence quotient (IQ) tests originated as a way to evaluate children against the average performance levels of their peers. Children with lower IQs received special education, and those with higher IQs were considered gifted. In addition to evaluating children, today's IQ tests are commonly given to adults, often in a corporate setting, to measure their learning ability and knowledge in an unbiased way. Five main types of IQ tests exist: Wechsler Intelligence Scale for Children (WISC), Stanford-Binet, Wechsler Adult Intelligence Scale---Third Edition (WAIS--III), KABC-II: Kaufman Assessment Battery for Children, Second Edition and Wechsler Preschool and Primary Scale of Intelligence---Third Edition (WPPSI--III).

Wechsler Intelligence Scale for Children (WISC)

The Wechsler Intelligence Scale for Children (WISC) is currently in its fourth revision, so the test is sometimes also known as the WISC-IV. The WISC is designed for children ages 6 to 16. The WISC uses 16 sub-tests, including Visual Digit Span (VDS), Coding Recall (CDR) and Information Multiple Choice (INMC), to measure ability in five key areas. Those areas are verbal comprehension, perceptual reasoning, processing speed, memory and executive function, which is theorized to control the function of other abilities.

Stanford-Binet

The Stanford-Binet IQ test is designed for people ages 2 to 23 to determine cognitive and IQ abilities. Performance in four areas, including short-term memory skills, quantitative reasoning, abstract and visual reasoning and verbal reasoning, determines the test-taker's score. The Stanford-Binet uses 15 sub-tests to determine abilities in the four areas, including vocabulary, number series, memory for sentences, equation building and pattern analysis.

Wechsler Adult Intelligence Scale---Third Edition (WAIS--III)

Wechsler Adult Intelligence Scale---Third Edition (WAIS--III) is intended for adults between the ages of 18 and 80. The WAIS-III is used to determine intelligence, but it can also assist with evaluating personality and may be used following a brain injury to assess the level of damage. The test measures verbal, performance, symbol search, letter-number sequencing and matrix-reasoning capabilities by testing 14 skills, including arithmetic, picture arrangement and comprehension.

KABC-II: Kaufman Assessment Battery for Children, Second Edition

The KABC-II: Kaufman Assessment Battery for Children, Second Edition is used for ages 3 to 18. KABC-II was designed in response to criticism that other IQ tests don't give an accurate measure of minorities' IQ due to unintended natural biases inherent in the tests. The KABC-II is designed to require minimal verbal responses, thus eliminating cultural barriers due to language insufficiency. The questions strive to be culturally neutral to make it accessible to a wide range of children from different backgrounds. Conceptual thinking, face recognition, word order and hand movements are some of the areas tested.

Wechsler Preschool and Primary Scale of Intelligence---Third Edition (WPPSI--III)

The Wechsler Preschool and Primary Scale of Intelligence---Third Edition (WPPSI--III) has two versions. One is used for children ages 2 years, 6 months to 3 years, 11 months, and the other is for children ages 4 to 7 years, 3 months. The WPPSI-III measures verbal, performance and processing speed abilities through sub-tests like symbol search, picture naming and non-fluid reasoning.