What are the Explanations for The Observed Score Differences?
Many hypotheses have been proposed to explain why these differences occur. In general, these explanations can be classified according to genetics, social and cultural factors and the nature of the measurement of the predictor (e.g., Goldstein, Scherbaum & Yusko, 2009; Neisser et al., 1996; Verney et al., 2005). It is unlikely that any one factor can explain or account for all the differences observed, and the factors impacting scores will vary between groups. For example, language and cultural familiarity are likely to apply to a greater degree to immigrants and Latinos/Hispanics in the US than they would to African-Americans. We briefly consider each of these three classes of explanations for score differences.
Explanations based on genetics
One set of explanations is based on heritability and genetic aspects of individual differences (Herrnstein & Murray, 1994; Neisser et al., 1996). The basic idea here is that many individual differences (e.g., cognitive ability, personality) have a genetic basis and are passed from parent to offspring. Thus, the observed differences reflect real differences in the individual difference variable. This has been the most controversial when applied to cognitive abilities as the only conclusion is that people are born intelligent or unintelligent and there is nothing that can be done to change it. As Nisbett and colleagues (2012) argue, while the evidence suggests that genetics can play a role, the role is much smaller than the proponents of this approach claim, and the interactions between the genotypes and environment are too complex to pinpoint the precise impact of genes on individual differences. Moreover, the evidence does not show that the genetic component is intertwined with race and ethnicity. However, the arguments for this perspective on the differences in scores seems to assume that the research does show such an interrelationship.
Numerous explanations explicitly or implicitly build on the position that there are inherent differences in cognitive ability between race groups. One example is the Spearman hypothesis (Jensen, 1998; Spearman, 1927), which predicts that racial differences in test performance increase as the cognitive loading of a test increases. Essentially, this means that the better the test is at measuring cognitive ability (i.e., a higher g load), the greater the differences that will be observed between races. This hypothesis is premised on the assumption that the observed differences are true differences between groups.