The Wechsler Adult Intelligence Scale

The Wechsler Adult Intelligence Scale (WAIS) is an intelligence test that was first published in 1955 and designed to measure intelligence in adults and older adolescents. The test was designed by psychologist David Wechsler who believed that intelligence was made up a number of different mental abilities rather than a single general intelligence factor.

Wechsler was dissatisfied with what he believed were the limitations of the Stanford-Binet test. Among his chief complaints about that test were the single score that emerged, its emphasis on timed tasks, and the fact that the test had been designed specifically for children and was therefore invalid for adults.

As a result, Wechsler devised a new test during the 1930s that was known as the Wechsler-Bellevue Intelligence Scales. The test was later revised and became known as the Wechsler Adult Intelligence Scale or WAIS.

How did the Wechsler Adult Intentelligence Test compare to the Stanford Binet?

One interesting thing to note is that Alfred Binet, the developer of the world's first intelligence test, also believed that intelligence was far too complex a subject to be sufficiently described by a single number. The goal of his original test was to help identify children who needed specialized help in school and he felt that a variety of individual factors, including a child's level of motivation, could influence test scores.

In a sense, Wechsler's test was a return to many of the ideas that Binet had also espoused. Instead of giving a single overall score, the WAIS provided a profile of the test-taker's overall strengths and weaknesses. One benefit of this approach is that the pattern of scores can also provide useful information. For example, scoring high in certain areas but low in others might indicate the presence of a specific learning disability.

Like the traditional Stanford-Binet test, the WAIS also provides an overall score. However, Wechsler utilized a different approach to calculate this number. As you might remember from reading about the history of intelligence testing, scores on the early Stanford-Binet were derived from dividing mental age by chronological age.

On the WAIS, Wechsler instead compared scores of the test-taker to those of others in his or her general age group. The average score is fixed at 100, with approximately two-thirds of all scores falling somewhere between 85 and 115. Test scores that fall between these two numbers are considered average, normal intelligence.

Many other intelligence tests later decided to adopt Wechsler's method, including the modern version of the Stanford-Binet.

There have been four different versions of the WAIS:

• WAIS (1955)
• WAIS-R (1981)
• WAIS-III (1997)
• WAIS-IV (2008)

The current version of the WAIS was released in 2008 and includes ten core subtests as well as five supplemental subtests.

The test provides four major scores:

• Verbal Comprehension
• Perceptual Reasoning
• Working Memory
• Processing Speed

Additionally, the WAIS-IV provides two overall summary scores:

• Full-Scale IQ
• General Ability Index

The WAIS surpassed the Stanford-Binet in use during the 1960s. Today, the WAIS is the most frequently intelligence test in the world with both adolescents and adults. Data collection for the newest version of the test is currently underway, and the WAIS 5 is expected to be released in 2019.