Home › Instruments › WAIS-IV

Assessment instruments

Wechsler Adult Intelligence Scale (WAIS-IV)

16 years 0 months to 90 years 11 months

The Wechsler Adult Intelligence Scale, Fourth Edition, is the most widely used individually administered cognitive assessment for adults, covering ages 16 years 0 months to 90 years 11 months. It is also searched for as the WAIS-IV test, the adult IQ test and adult cognitive testing.

Adults are usually referred for cognitive assessment for different reasons than children. The question is more often about explaining a long-standing pattern than about predicting a trajectory, and the results frequently make sense of something a person has noticed about themselves for years.

What does the WAIS-IV measure?

The WAIS-IV produces four index scores and a Full Scale IQ.

• Verbal Comprehension. Vocabulary, verbal reasoning and general verbal knowledge.
• Perceptual Reasoning. Non-verbal problem solving, visual analysis and reasoning with patterns.
• Working Memory. Holding and manipulating information over short intervals.
• Processing Speed. Speed and accuracy on simple, repetitive visual tasks.

The WAIS-IV keeps perceptual reasoning as a single index, where the children's version separates visual spatial and fluid reasoning. This is worth knowing if you are comparing an adult result to a childhood WISC score, because the structures are not directly equivalent.

Why would an adult have a cognitive assessment?

The most common reason we see is as part of an adult ADHD or autism assessment, where the cognitive profile helps distinguish attentional difficulty from other explanations. It also comes up where an adult is seeking evidence for university or workplace adjustments, where a specific learning disorder was never identified in childhood, where intellectual disability is being formally established, or where a change in functioning needs to be characterised.

For NDIS purposes, cognitive assessment is often requested alongside adaptive functioning measures, because eligibility on the basis of intellectual disability requires both.

What happens during a WAIS-IV assessment?

You work one-to-one with a psychologist through a set of structured tasks. Some are conversational, such as defining words or explaining how two concepts relate. Others involve arranging blocks, completing visual patterns, recalling sequences of numbers or working quickly through symbol-matching tasks.

Most adults find it more engaging than they expected and more tiring than they expected. Breaks are built in. There is nothing to prepare, and preparing would undermine the result.

How are WAIS-IV scores reported?

Performance is compared against a normative sample of adults in the same age band, so a score reflects how you performed relative to people your own age rather than against a fixed standard. Reports give standard scores, percentile ranks and confidence intervals.

In adults, the gap between indices is often the most clinically useful part of the result. A strong verbal comprehension score sitting alongside a much weaker processing speed score describes a real and recognisable experience, and it frequently explains why work that should be straightforward has always taken longer than it seems it should.

Can the WAIS-IV diagnose ADHD or autism?

No. Neither condition has a cognitive signature that can be identified from WAIS-IV scores. Certain patterns appear more often in people with ADHD, but they appear in people without it as well, and plenty of people with ADHD produce an unremarkable profile.

The WAIS-IV contributes to those assessments by characterising cognitive strengths and difficulties and by helping rule other explanations in or out. Diagnosis rests on developmental history, standardised interviews, behavioural measures and collateral information.

Related instruments

This page is general information about an assessment instrument and is not clinical advice. Whether a particular assessment is appropriate depends on the individual and the question being asked.