David Wechsler

David "Weshy" Wechsler (January 12, 1896 – May 2, 1981) was a Romanian-American psychologist best known for creating the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC). He designed these tests to better understand his patients at Bellevue Hospital. In 2002, a survey by *Review of General Psychology* ranked him as the 51st most cited psychologist of the 20th century.

Wechsler was born into a Jewish family in Lespezi, Romania, and moved to the United States with his parents as a child. He studied at the City College of New York and Columbia University, earning a master’s degree in 1917 and a Ph.D. in 1925 under Robert S. Woodworth. During World War I, he worked with the U.S. Army to develop psychological tests for screening new recruits, studying under Charles Spearman and Karl Pearson.

After brief stints elsewhere, including five years in private practice, Wechsler became chief psychologist at Bellevue Psychiatric Hospital in 1932, a role he held until 1967. In 1947, he joined a mission to establish a mental health program and clinic for Jewish Holocaust survivors.

Wechsler is most famous for his intelligence tests. He strongly advocated for the role of nonintellective factors in testing, arguing that intelligent behavior involves more than just intellectual ability. He found the 1937 Binet scale unsatisfactory, particularly its single score, and created his own battery to learn more about his Bellevue patients. His approach differed sharply from the Binet scale, then considered the gold standard in intelligence testing. By the 1960s, the WAIS had surpassed the Stanford–Binet tests in popularity, partly because the 1960 version of the Stanford–Binet was less carefully developed than earlier forms.

Although his tests did not directly measure nonintellective factors, they accounted for them in their underlying theory. The WAIS was first developed in 1939 as the Wechsler-Bellevue Intelligence Test. From it, he derived the WISC in 1949 and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) in 1967. These tests remain based on his definition of intelligence as “the global capacity to act purposefully, to think rationally, and to deal effectively with one’s environment.”

Wechsler introduced several innovations to intelligence testing. He abandoned the quotient scores used in older tests, instead setting the mean intelligence at 100 and adding or subtracting 15 points for each standard deviation above or below the mean. While he did not reject the concept of general intelligence, as taught by his mentor Charles Spearman, he divided intelligence into two main areas: verbal and performance (non-verbal) scales, each assessed with different subtests.

Wechsler died on May 2, 1981.