Intelligence, Theories of

Ideas about the nature of human intelligence have long historical roots. However, it was not until the late nineteenth century that modern theories of intelligence emerged among European and American researchers. These theories, which stressed the importance of scientific measurement, also marked the rise of experimental psychology as an academic discipline. The ways in which experimental psychologists conceptualized and measured intelligence would have a profound impact on American society, especially in relation to how American public schools structured learning opportunities for students in the first half of the twentieth century. This entry looks at the evolution of theories about intelligence during the nineteenth and twentieth centuries.