ABSTRACT
The principal difference between definitions of intelligence lies in their scope. Spearman argued that since g was important in almost all tasks, it was the most important aspect of intelligence. However, they differ in that crystalline intelligence seems to increase with age while fluid intelligence peaks in early adulthood and then declines with age. Most approaches to the study of intelligence are based on the concept of mental competence and, consequently, research tends to be restricted to the domain of education. Much of what Spearman and Thurstone would have described as intelligence arises from the processes of the componential sub-theory, and the distinction between fluid and crystallized intelligence can be recognized in the processes of the experiential sub-theory. Modern intelligence tests do not provide effective assessment of much that Sternberg considers important, and new measurement methods are needed to assess its predictive power.
