2009 Int J Neuroscience
International Journal of Neuroscience, 119:691–731, 2009 Copyright C2009 Informa Healthcare USA, Inc. ISSN: 0020-7454 / 1543-5245 online DOI: 10.1080/00207450802325843 WHOLE BRAIN SIZE AND GENERAL MENTAL ABILITY: A REVIEW J. PHILIPPE RUSHTON C. DAVISON ANKNEY Departments of Psychology and Biology University of Western Ontario London, Ontario, Canada We review the literature on the relation between whole brain size and general mental ability (GMA) both within and between species. Among humans, in 28 samples using brain imaging techniques, the mean brain size/GMA correlation is 0.40 (N=1,389;p<10 −10 ); in 59 samples using external head size measures it is 0.20 (N=63,405;p<10 −10 ). In 6 samples using the method of correlated vectors to distillg, the general factor of mental ability, the meanris 0.63. We also describe the brain size/GMA correlations with age, socioeconomic position, sex, and ancestral population groups, which also provide information about brain–behavior relationships. Finally, we examine brain size and mental ability from an evolutionary and behavior genetic perspective. Keywordsbrain size, brain volume, intelligence, IQ scores, magnetic resonance imaging Replication is a crucial part of the scientific process. Conceptual replication—across procedures, populations, and species—provides evidence of a reliable relationship—especially in the behavioral sciences that depend on correlational studies. This is our fifth review of the relation between brain size and general mental ability (GMA; Rushton & Ankney, 1995, 1996, 1997, 2007). It covers important new findings but also repeats some material that is still not widelyknown. Received 21 February 2008. Address correspondence to J. Philippe Rushton, Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada. E-mail: [email protected] 691 Downloaded By: [Canadian Research Knowledge Network] At: 15:35 13 March 2009