WAIS-5 updates intelligence testing structure for adults

David Susman, PhD, reviewed this analysis of the Wechsler Adult Intelligence Scale (WAIS), which stands as the primary intelligence assessment tool globally for adolescents and adults. Unlike single-score metrics, the WAIS evaluates distinct mental abilities to generate a detailed cognitive profile.

Origins beyond Stanford-Binet limitations

David Wechsler developed the scale after identifying significant flaws in the Stanford-Binet test, specifically its reliance on timed tasks and its unsuitability for adult populations. He criticized the earlier method’s focus on a single general score, arguing that intelligence comprises multiple distinct abilities rather than one factor.

Wechsler initially created the Wechsler-Bellevue Intelligence Scales in the 1930s, which later evolved into the WAIS introduced in 1955. This new instrument addressed Stanford-Binet weaknesses by providing varied scores instead of just one overall number, offering a nuanced view of strengths and weaknesses.

Scoring methodology and age comparisons

While the traditional Stanford-Binet calculated scores by dividing mental age by chronological age, Wechsler adopted a different approach. The WAIS compares a test-taker’s performance against peers in their specific age group. The average score is fixed at 100, with approximately two-thirds of results falling between 85 and 115.

In the current version, scores between 90 and 110 are classified as average intelligence. This deviation-based scoring method has been widely adopted by other tests, including the modern Stanford-Binet. The pattern of scores can also reveal specific learning disabilities if an individual scores high in some areas but low in others.

Evolution through four prior versions

The WAIS has undergone four major revisions since its inception. The original 1955 edition revised the 1939 Wechsler-Bellevue scales. The 1981 WAIS-R added new norms while retaining validity data from the original, featuring six verbal and five performance subtests that yielded verbal, performance, and overall IQ scores.

The 1997 WAIS-III expanded to seven verbal and six performance subtests, adding secondary scores for perceptual organization, processing speed, verbal comprehension, and working memory. The 2008 WAIS-IV utilized 10 main and five supplemental subtests to produce a Full-Scale IQ and General Ability Index, alongside individual index scores for reasoning, speed, comprehension, and memory.

WAIS-5 launch details and structure

The fifth iteration, WAIS-5, is scheduled for release in the fall of 2024. This version consists of seven primary subtests used to calculate the full-scale IQ score and ten secondary subtests for expanded clinical use. It provides five major index scores: Fluid Reasoning, Processing Speed, Verbal Comprehension, Visual-Spatial Ability, and Working Memory.

Clinical benefits and diagnostic utility

The WAIS surpassed the Stanford-Binet in usage during the 1960s and remains the most frequently administered intelligence test worldwide today. Clinicians value the tool for its well-established nature and good test-retest reliability. It accurately measures current intellectual status and functioning, serving as a useful instrument for assessing mild, moderate, and severe traumatic brain injury (TBI).

Beyond general intelligence measurement, neuropsychologists and rehabilitation psychologists use the WAIS to evaluate cognitive functioning in individuals with psychiatric conditions or brain injuries. The test helps identify patterns of brain dysfunction and determine affected areas following trauma.

Limitations and accessibility constraints

Despite its widespread use, the WAIS has notable drawbacks. It does not assess non-academic skills such as motivation, creativity, emotional intelligence, or social skills, which contribute significantly to success and well-being. Consequently, it offers a relative measure rather than a complete view of a person’s potential or talents.

Administration restrictions exist for individuals with vision, auditory, or motor impairments. Additionally, options for non-English speakers are limited; currently, only two Spanish versions are available—one for speakers from Spain and another for those from Mexico. Scores may also vary for neurodivergent adults depending on unique traits, and the test may not be suitable for older adults, particularly those over the age of 89.