Studies Have Shown That

A longitudinal study discussed in your textbook used MRI scans to study the development of the cerebral cortex as children aged. Which of the following is one of the findings from this study? A) In the brightest children, the cerebral cortex is always thicker than it is in other children. B) The cortex in very bright children develops more rapidly and for a longer time than it does in other children. C) The cortex in average children reaches its maximum thickness several years later than it does in bright children. D) In children with average IQs, the cortex reaches maximum thickness at age 11 or 12.

A major problem with genetic explanations of racial differences in IQ is that: A) although intelligence differs between groups, it does not differ within groups. B) heritability estimates used in supporting genetic explanations of group differences are based mainly on white samples. C) the studies typically use black and white children from highly similar socioeconomic groups. D) the explanations are based on linkage studies.