Originally developed in 1949, the WISC was intended as an improvement over the Wechsler–Bellevue Intelligence Scale of 1939, which in turn improved upon the older, uni-dimensional Binet Scale. The test was administered to determine cognitive function in children aged 5 to 15. In recent years, 6 - 16 has become the preferred range.
The WISC measures two aspects of intelligence in children: verbal and performance intelligence. Verbal intelligence includes aspects like vocabulary and comprehension; performance intelligence includes matrix reasoning and picture completion. The WISC requires between 65 – 80 minutes for administration and generates a score typical of most IQ tests. The average score is 100 with higher scores indicating higher than average intelligence and lower scores indicating lower levels of intelligence.
This instrument is sometimes used to help diagnosis low cognitive functioning or disability in teens and adults instead of using the more age-appropriate WAIS, which may be too difficult for this population group.