Final answer:
David Wechsler developed the Wechsler-Bellevue Intelligence Scale in 1939, which later became the WAIS and has been periodically revised as the WISC-V and other versions, remaining a cornerstone of intelligence testing.
Step-by-step explanation:
In 1939, psychologist David Wechsler developed the Wechsler-Bellevue Intelligence Scale, which laid the groundwork for contemporary intelligence testing.
Wechsler's Integrative approach combined subtests measuring various verbal and nonverbal skills, as he believed intelligence was a comprehensive ability to act with purpose, think rationally, and effectively engage with one's environment.
These tests, including the widely known Wechsler Adult Intelligence Scale (WAIS), Wechsler Intelligence Scale for Children (WISC), and Wechsler Preschool and Primary Scale of Intelligence (WPPSI), have been periodically updated to maintain accuracy and relevance through norming and standardization against contemporary populations.
The Wechsler scales have their origins in the work of earlier psychologists like Alfred Binet and Francis Galton, who pioneered the field of intelligence testing.
Wechsler improved upon these earlier efforts by creating a test that offered a more balanced assessment of a person's intelligence beyond just verbal capabilities. Modern versions of Wechsler's tests, such as the WISC-V, are still used extensively in schools and clinical settings to evaluate intelligence in both children and adults.