Looking Down on Human Intelligence

Ian J. Deary's new book is about the biology of individual differences in intelligence, with most modern research described in the last chapters, and some of the early writings are mainly of historical interest.

Abstract

Human mental ability differences have a hierarchical structure, and may be viewed at levels from general ability (g) to specific abilities. Ability differences show moderate stability across the lifespan, moderate heritability, and some predictive power in the fields of education, work, and social life. The most persistent mystery is the origin(s) of individual differences in cognitive and biological processes. The book reviews the search for these origins. The chapters cover historical work from antiquity to the 20th century. Research addresses the search for the origins of mental ability differences in cognitive components, reaction times, and inspection times. Biological areas such as brain size, event-related potentials, functional brain imaging, and molecular genetics are presented. The book identifies solid findings and sites of progress and criticizes empirical and conceptual weaknesses in the field.