Intelligence test scores are related to brain glucose metabolism. This helps validate that the test scores were not meaningless numbers representing a statistical artifact. In fact, as neuroimaging studies of intelligence continue to increase, old criticisms about intelligence test scores having no meaning are less and less meaningful, if they were ever meaningful at all.
........
We found a nearly perfect linear relationship between the g – loading of each subtest of the WAIS and the amount of gray matter correlated to each subtest score (Colom et al .,2006a ). Thus, we come to another important observation. IQ tests have the advantages of a standardized test battery but the scores combine the general factor along with other specific factors. So the question of how intelligence correlates to brain structure and function depends on whether the question is about g or about more specific mental abilities. Inconsistent results among these early studies likely result from confusion on this issue as well as from issues about sampling and image analysis.
