This chapter reviews major theories of intelligence. The theories are grouped into four major theory types: (1) psychometric theories; (2) cognitive theories; (3) cognitive-contextual theories; and (4) biological theories. Psychometric theories derive from studying individual differences in test performance on cognitive tests. Questions about the structure of human intelligence, including the importance of general intelligence, have dominated the psychometric theories. Cognitive theories derive from studying the processes involved in intelligent performance. These processes range from the very simple (e.g., inspection time) to the fairly complex (e.g., working memory). Different theorists have focused on different processes (or aspects of these processes, such as processing speed). Cognitive-contextual theories emphasize processes that demonstrate intelligence within a particular context (such as a cultural environment). Major theories include Sternberg’s triarchic theory, Gardner’s theory of multiple intelligences, and Piaget’s theory of development. Biological theories emphasize the relationship between intelligence, and the brain and its functions. Numerous relationships have been found, but none have been elaborated into a detailed theory of the neuropsychology of intelligence. The chapter concludes with several questions for future research in the area of intelligence.
Spearman’s Two Factor Theory