William Stern

William Stern was a German psychologist best known for his work in intelligence testing and psychology of personality. He is credited with introducing the concept of "mental age," which helped to develop the modern IQ test. Stern believed that intelligence should be measured not just by age-related performance but also by individual potential. His work laid the foundation for understanding human intelligence as a complex trait influenced by both genetics and environment. Additionally, he made significant contributions to educational psychology and the study of individual differences in personality.