WAIS IV - Wechsler Adult Intelligence Scale

 The Wechsler Adult Intelligence Scale (WAIS-IV) is an IQ test used in adults (ages 16-90) to assess cognitive abilities across different domains. It can take around 60-90 minutes to complete

Limitations in the context of autism:

• Language and communication challenges can impact performance on subtests that heavily rely on language abilities.
• Sensory sensitivities and attentional difficulties affect their performance on tasks requiring sustained attention or visual processing.
• Social and contextual factors/aspects of intelligence relevant to autism not considered as the test focuses on cognitive abilities.
• [Also see post on why IQ tests problematic in autistics] 

WAIS-IV has 10 core subtests which are organized into four index scores.

1. Verbal Comprehension Index (VCI):
• Similarities: verbal reasoning and concept formation.
• Vocabulary: ability to define words and understand their meaning.
2. Perceptual Reasoning Index (PRI):
• Block Design: visual-motor coordination and spatial perception.
• Matrix Reasoning: non-verbal reasoning and problem-solving skills.
• Visual Puzzles: ability to analyze and synthesize visual information.
• Picture Completion: visual perception and attention to detail. Presented with incomplete pictures and are required to identify the missing part or detail.
3. Working Memory Index (WMI):
• Digit Span: attention, concentration, and working memory by assessing the ability to repeat a series of digits forward and backward.
• Arithmetic: mental arithmetic skills and working memory.
4. Processing Speed Index (PSI):
• Symbol Search: visual scanning speed and processing speed.
• Coding:motor speed, attention, and visual-motor coordination.

Scoring and interpretation

Index scores are derived from specific combinations of subtests and provide an overall assessment of an individual's cognitive strengths and weaknesses in those domains.

The Full-Scale IQ (FSIQ) is the combination of the index scores. It represents overall intellectual functioning and is calculated based on the combined performance across all subtests.

Interpretation involves comparing an individual's performance to normative data (percentile ranks, confidence intervals, and descriptive categories), considering the person's age and the index and subtest scores obtained. 

History
WAIS was first developed by David Wechsler as an adaptation of his earlier intelligence tests, the Wechsler-Bellevue Intelligence Scale (1st Ed 1955, 4th Ed 2008).