The study and measurement of human intelligence is one of the most controversial subjects in psychology. For much of its history, the focus has been on differences between people, what it means for one individual to be more intelligent than the other, and how such differences might have arisen. With the emphasis on these issues, the efforts to understand the general nature of intelligence have been obscured. The author provides clear, comprehensive, and extremely readable introduction to this difficult subject. In addition to a discussion of the traditional topics raised by IQ tests, this book attempts to bring the theory and data of cognitive psychology and cognitive neuroscience to bear on some of these other, equally important scientific questions.