Wechsler Adult Intelligence Scale - History

History

Wechsler's scale is founded on his definition of intelligence, which he defined as "... the global capacity of a person to act purposefully, to think rationally, and to deal effectively with his environment." He believed that intelligence was made up of specific elements that could be isolated, defined, and subsequently measured. However, these individual elements were not entirely independent, but were all interrelated. His argument, in other words, is that general intelligence is composed of various specific and interrelated functions or elements that can be individually measured.

This theory differed greatly from the Binet scale which, in Wechsler's day, was generally considered the supreme authority with regards to intelligence testing. A drastically revised new version of the Binet scale, released in 1937, saw much attack from David Wechsler (for whom the original Wechsler-Bellevue Intelligence scale and the modern Weschler Adult Intelligence Scale IV are named after), who had many criticisms of this newly revised intelligence scale.

• Wechsler was a very influential advocate for the concept of nonintellective factors, and he felt that the 1937 Binet scale did not do a good job of incorporating these factors into the scale (nonintellective factors are variables that contribute to the overall score in intelligence, but are not made up of intelligence-related items. These include things such as lack of confidence, fear of failure, attitudes, etc.).
• Wechsler did not agree with the idea of a single score that the Binet test gave.
• Wechsler argued that the Binet scale items were not valid for adult test-takers because the items were chosen specifically for use with children.
• The "Binet scale's emphasis on speed, with timed tasks scattered throughout the scale, tended to unduly handicap older adults."
• Wechsler believed that "mental age norms clearly did not apply to adults."
• Wechsler criticized the then existing Binet scale because it did not consider that intellectual performance could deteriorate as a person grew older."

These many criticisms of the 1937 Binet test gave rise to the Wechsler-Bellevue scale that was released in 1939. In subsequent years this scale has been revised many times, resulting in the present day WAIS-IV. However, many of the original concepts that Wechsler argued for have become standards in psychological testing, included of which are the point scale concept and the performance scale concept.