Designed originally by to measure verbal and quantitative reasoning, short-term memory and other mental functions, intelligence testing attempts to determine some sense of an individual's intellectual potential. Test designers approach testing differently, and scores from one test are not interchangeable with scores from another. Tests assessing reading, writing or math knowledge are achievement tests, not intelligence tests.
Most commonly used in the United States to measure intelligence in children, the Wechsler Intelligence Scale for Children (WISC I through IV) and Stanford-Binet Intelligence Scales assess an individual's verbal reasoning, abstract and visual reasoning, quantitative reasoning and short-term memory.
Other tests include the Wechsler Adult Intelligence Scale (WAIS-III) (adults), Reynolds Intellectual Assessment Scales (RIAS), Universal Nonverbal Intelligence Test (UNIT), Woodcock-Johnson-R, Wechsler Preschool and Primary Scale of Intelligence (WPPSI) (young children), Kaufman Brief Intelligence Test (KBIT) and Differential Ability Scales (DAS) (children).
Tests vary, based on the age group being tested or differing theoretical ideas. While the scales used deviate considerably, the typical standard is that 100 equals average intelligence, with a standard deviation of 15 in either direction. Each new revision of a test sets a new (higher) standard of norm or average to compensate for what is known as the Flynn Effect---an increase in average intelligence over time for reasons not completely understood but perhaps related to nutrition, environmental stimulation and other factors of a developing society.
IQ test questions are not about knowledge but about thinking skills, and time taken to answer each question is factored into the score. The less time needed to complete the test, the higher the overall ability to think through problems.
Uses in Education
Intelligence scores tend to predict academic aptitude and provide a guide to the student's potential weaknesses and strengths. Tests also are used to identify students classified as either learning disabled or gifted to design stimulating curricula.
Uses in the Workplace
Intelligence testing in specialized fields is not new, but some companies are turning to IQ tests to help them choose between candidates or determine where an employee best fits. The potential for abuse is high in this application as the test givers and score interpreters may not possess sufficient psychological understanding to appropriately understand what a score means.
One persistent controversy about intelligence testing is the argument that the tests are designed by a social class (educated and relatively affluent) whose experiences and vocabulary differ drastically from an inner-city child (for instance) raised in poverty who may be taking the test, thus skewing the outcome.
Influences on Intelligence
Hereditary influences and environmental influences seem to play a role in test scores. Research demonstrates that a child's intellectual development may dramatically increase when provided with a stimulating environment. Alternately, the measurable intelligence of a child deprived of stimulation may decrease.