The purpose of the present study is to explain variation in academic achievement with general cognitive ability and specific cognitive abilities. Grade point average, Wide Range Achievement Test III scores, and SAT scores represented academic achievement. The specific cognitive abilities of interest were: working memory, processing speed, and spatial ability. General cognitive ability was measured with the Raven's Advanced Progressive Matrices and the Mill Hill Vocabulary Scales. When controlling for working memory, processing speed, and spatial ability, in a sample of 71 young adults (29 males), measures of general cognitive ability continued to add to the prediction of academic achievement, but none of the specific cognitive abilities accounted for additional variance in academic achievement after controlling for general cognitive ability. However, processing speed and spatial ability continued to account for a significant amount of additional variance when predicting scores for the mathematical portion of the SAT while holding general cognitive ability constant. © 2006 Elsevier Inc. All rights reserved.
Keywords: Intelligence; Spatial ability; Academic achievement
Academic achievement scores of high school students correlate between .50 and .70 with IQ scores (Jensen, 1998), and performance on standardized measures of academicachievement can beusedtoaccurately estimate IQ scores (Frey & Detterman, 2004). While there is empirical evidence for a strong association between generalcognitiveabilityandacademicachievement,there is still anywhere from 51% to 75% of the variance in academic achievement that is unaccounted for by measures of general cognitive ability alone. Moreover, understanding the nature of the relationship between general cognitive ability and academic achievement has widespread implications for both practice and theory. Several specific cognitive abilities have the potential to further an understanding of the components of
general cognitive ability. Recent research focused on delineating the structure of general cognitive ability has attempted to identify separable constructs to explain individual differences in psychometric ‘g’. These same constructs may also be relevant for understanding academic achievement. As an example, information processing theory suggests that overall mental efficiency can account for a large portion of the individual differences in ‘g’ (Vernon, 1983). Processing speed and working memory are two cognitive processes that have each been used to explain what drives mental efficiency and thus general cognitive ability. Jensen (1992) was able to account for 40% of the variance associated with ‘g’ using Reaction Time (RT) variables — the intraindividual median (RTmd) and the standard deviation (RTSD). Of that 40%, 63.5% was common to both variables, and 17.1% was specific to RTmd, and 19.4% was specific to RTSD. In addition to
Intelligence 35 (2007) 83–92
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