The WAIS was initially introduced in 1955 as an alternative to the Binet Scale to measure intelligence in adults. By the 1960's, the WAIS had surpassed even the newer version of the Binet Scale, the Stanford-Binet Intelligence Scales, as the preeminent tool for testing adult intelligence levels.
Like the WISC, the WAIS undergoes frequent revision to improve the test and to keep its contents current. Early version measured only verbal and nonverbal intelligence; however, the 2008 version of the WAIS (WAIS-IV) included ten sub-tests that examined many facets of human intellect, including memory. This makes the test a potentially useful instrument in the early diagnosis of Alzheimer's Disease.