📌 Key takeaways
- Wechsler replaced the old mental-age ratio with “deviation IQ,” comparing a person to others of the same age on a bell curve centred at 100.
- The Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children are among the most widely used IQ tests in the world.
- Wechsler’s tests assess several domains — verbal comprehension, working memory, processing speed and more — giving a profile rather than one number.
- Deviation IQ, standard scores and multi-domain profiles are now the norm, making Wechsler one of the most influential figures in testing.
What did Wechsler change?
Wechsler replaced the old mental-age ratio with “deviation IQ,” comparing a person to others of the same age on a bell curve centred at 100. This is how IQ is scored today.
What are the WAIS and WISC?
The Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children are among the most widely used IQ tests in the world.
Why measure multiple abilities?
Wechsler’s tests assess several domains — verbal comprehension, working memory, processing speed and more — giving a profile rather than one number.
What is his legacy?
Deviation IQ, standard scores and multi-domain profiles are now the norm, making Wechsler one of the most influential figures in testing.
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📅 Last updated: 2026-06-18 · ✔ Reviewed by the All-Lifes editorial team · About · Methodology