G explained.

This paper presents the hypothesis that the general factor, g, which emerges from psychometric batteries and which has been equated with general intelligence, is the result of a physical brain feature which enhances neural network efficiency and is determined for the brain in general. This conception of intelligence provides a resolution of the unity-versus-modularity debate in the intelligence field and yields specific predictions as to the nature and kind of brain features that will be found to provide a physical explanation for g. To avoid nosological confusion, it is suggested that 'n' be used to represent the neurological concept of general intelligence while 'g' should continue to denote the general factor emerging from mathematical analyses of mental test batteries.