A unified cognitive/differential approach to human intelligence: Implications for IQ Testing.

Individual differences have been mostly ignored in cognitive/experimental psychology since the birth of the field, while the measurement of cognitive abilities has become a successful field of applied psychology. Because of its separation from mainstream research psychology, cognitive ability testing has focused on application, often without providing sound theoretical basis for the tests. More recently, the gap between cognitive/experimental psychology and differential/psychometric research has been closing. This stems from a rediscovery of variation in cognitive abilities in experimental psychology, owing largely to the concept of working memory. We present process overlap theory, a new theory of intelligence that is informed by cognitive psychology. The theory explains the positive correlations between diverse tests on the basis of overlapping cognitive processes and reinterprets the general factor of intelligence, g, as a formative construct. The consequences of this approach are discussed, including a focus on specific abilities rather than on global scores in cognitive test results.