The Wechsler Adult Intelligence Scale

5 minutes

The Wechsler Adult Intelligence Scale is the most widely used instrument for assessing cognitive abilities. Here, you can learn about it and its benefits.

Written and verified by the psychologist Elena Sanz.

Last update: 09 June, 2023

Interest in measuring intelligence goes back decades. However, it’s never been an easy process. Originally, the concept was mixed with others such as morality, thinking, or the soul. Moreover, there were no reliable or objective measures of intelligence. Fortunately, there are now effective, practical, and useful tools for addressing this task. One such instrument is The Wechsler Adult Intelligence Scale (WAIS).

Different versions of this tool have been developed and updated over time, based on the latest advances in psychology and clinical research. Thanks to this fact, it’s become increasingly valid and reliable. Today, it includes current concepts and improved application procedures. As a matter of fact, from its origins, this scale has dominated the field of cognitive assessment.

If you want to know more about this measuring implement of human intelligence, carry on reading.

The Wechsler Adult Intelligence Scale

An article published in the Revista Galego-Portuguesa de Psicoloxía e Educación states that the first attempts to measure intelligence reliably and scientifically came from Alfred Binet and Théodore Simon.

They developed the initial scales for estimating the intelligence and educational needs of children. Later, psychometrics and statistics were added to the equation, and the first version of the WAIS emerged.

It appeared in 1955 and was developed by David Wechsler, an American psychologist. He saw intelligence as a set of factors that can be measured independently. In fact, by evaluating the cognitive profile in a specific way, both its strengths and weaknesses are measured. Consequently, the test gives an overall as opposed to a unitary result.

According to an overview published in the Graduate Journal of Counseling Psychology, the Wechsler intelligence scale for adults has a long history. In fact, there have been four different versions for measuring intelligence in adults and other variants for the child and adolescent population. For example, the WISC and WPPSI scales.

You might also like to read Alfred Binet: How to Measure Intelligence

Wooden cubes symbolizing the Weschler Adult Intelligence Scale — The Weschler Adult Intelligence Scale has a place in the field of cognitive assessment.

The WAIS-IV

The WAIS-IV is the most recent version of the Wechsler Adult Intelligence Scale. It came to light in 2008 and presented certain variations from previous versions. Some of the most important, as noted by Pearson Clinical, include the following:

Less time is required for its employment.
Improved psychometric properties (greater validity and reliability).
More suitable for the elderly as they may have sensory or mobility deficits or slower reaction rates.

However, the biggest novelty is the substitution of the dual IC for the total IC. In previous versions, the scale offered two main measures: verbal and manipulative intelligence quotient. Today, this approximation has been replaced by the measurement of a quartet of point indices, in addition to a General Ability Index (GAI).

Verbal comprehension

This subscale measures verbal and semantic richness, verbal abstraction competence, associative thinking, verbal comprehension and expression, and learning and memory capacity. It contains four specific tasks, as follows:

Vocabulary.
Similarities.
Information.
Comprehension.

Perceptual reasoning index scale

In this case, aspects such as the ability to analyze and visually synthesize, the ability to compare and establish analogies, abstract reasoning, and object identification are evaluated. It’s conducted via the following five tasks or tests:

Block design.
Matrix reasoning.
Visual puzzles.
Figure weights.
Picture completion.

Working memory index scale

This third subscale seeks to measure attention and concentration, auditory memory, ability to use abstract numerical concepts, and working memory. Its three tests are as follows:

Digit Span.
Arithmetic.
Letter-number sequencing.

Processing speed index scale

The last three techniques evaluate factors such as perceptual speed and precision, visual motor skills, associative learning, and selective attention, via the following tasks:

Symbol Search.
Coding.
Cancellation.

How the WAIS-IV is used and scored

The WAIS-IV can be used with individuals between the ages of 16 and 89. It takes between 60 and 90 minutes to complete. It’s an individual test and the person receives points for each item they answer correctly.

Measurements are observed for the four subscales. This allows the strongest and weakest areas of the individual to be specified. In addition, a full-scale IQ (FSIQ) and a general ability index (GAI) are obtained. The latter is more useful and reliable if the individual exhibits certain sensory deficits or there’s a great discrepancy in their scores for the different tests.

It’s worth mentioning that the results obtained from this scale are interpreted based on the comparison of the individual with others of the same age or characteristics. Therefore, it can be inferred if they’re above or below average in each area.

You might be interested to read Spearman's Bifactorial Theory of Intelligence

The usefulness of the WAIS-IV

This scale is the most widely used in America and Europe to assess the cognitive profile of adults. It also helps to classify, describe, predict, and plan interventions (APA 2000).

According to research conducted by the University of Barcelona (Spain), the WAIS-IV is an essential instrument in the clinical and health field. It constitutes a reference pattern for the detection of intellectual disability. It’s also useful in the diagnosis of learning disorders and general developmental disorders.

In addition, the WAIS-IV is used in the forensic field. It can determine the legal responsibilities of the individual, after evaluating their abilities and cognitive capacities.

In the educational context, it can detect special educational needs and help with the planning of interventions in this regard. It can also be useful in terms of vocational guidance. And, in the human resources sector, it helps to identify if an individual has the necessary skills for a job, prepare training plans, and recommend promotions or relocations.

Application of the Weschler adult intelligence scale — Reasoning, working memory, verbal comprehension, and thinking speed are tested by the WAIS-IV.

Limitations

Despite the broad utility of this test, it also has some notable limitations. For example, as suggested by the Consejo General de la Psicología (Spain), it can’t be used in individuals with physical disabilities. Moreover, adaptations in other languages are lacking. In addition, all the validation studies have been conducted with samples from the US population. However, the instrument may not necessarily be appropriate in other countries.

Despite this, the WAIS-IV scale is a reliable instrument that’s led the field of intelligence assessment for decades. Indeed, it offers a complete cognitive profile. It also collaborates in the in-depth analysis of an individual’s abilities, obtains diagnoses, and makes adjustments in different areas and contexts. Therefore, it’s an essential tool in the field of psychology.