The Wechsler scales are the most widely used individually administered intelligence tests for children and adults. David Wechsler designed them to sample a broad range of verbal and nonverbal abilities and to yield both a full-scale IQ and index scores.

The current versions include the Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children. Subtests assess verbal comprehension, perceptual reasoning, working memory, and processing speed. Deviation IQ scores are derived by comparing the individual’s performance with age-based norms. The tests are used in clinical diagnosis, educational placement, neuropsychological assessment, and research.

Wechsler rejected the original mental-age approach in favor of a point-scale format and emphasized the importance of nonverbal as well as verbal performance. Successive revisions have updated norms, improved fairness, and refined the factor structure. The scales remain among the most carefully standardized and thoroughly validated instruments in psychology.

When a detailed, individually administered measure of cognitive ability is required, a Wechsler scale is often the instrument of choice.