Cognitive Tests, Race, and a Theory on Adverse Impact

The relationship between race and test score performance has been considered for some time. And, depending on your perspective--coming from a psychological, sociological, social psychological, or educational point of view--you will likely arrive at different explanations for the phenomenon.

Jonathan Cottrell, Daniel Newman, and Glenn Roisman offered a psychologically-based explanation in their recent work focusing on the gap between Whites and African Americans in cognitive test scores.* Of course, any such comparisons assume that a single test can measure cognitive ability across races and various groups--a point to which there is some debate. But, for the sake of this post, let's assume the tests have validity evidence. I do return to this issue at the end of the post, too.

The authors developed a model shown below, whereby race was associated with cognitive ability through two primary mechanisms: maternal advantage, which includes social class, mother's education, and mother's verbal ability and knowledge; and parenting factors, such as the surroundings where one is raised, birth order effects, and so on. 

From Cottrell et al., 2015.

From Cottrell et al., 2015.

The authors then collected various waves of data from over 1,300 families that participated in a longitudinal study: the National Institute of Child Health and Human Development (NICHD) Study of Early Childhood Care and Youth Development. They observed the following:

  • Racial differences in cognitive ability were apparent at the first time the children were tested (54 months) and remained relatively stable through the data collection time (age 15). 
  • Consistent with their predictions, race was associated with the maternal advantage variables, which were then related to the parenting factor variables. 
  • The model explained over 80 percent of the race gap in cognitive ability. 

So what to make of these findings? First, early childhood factors matter, and the differences as early as age 4 persist over time. To diverge somewhat from the psychological perspective, systemic racism theory suggests racism is embedded into all societal institutions, privileging Whites over others (the initiated reader can go here to learn more). This theory helps explain why differences in things like educational opportunities, work, income, physical environment, and birth weight all matter: not only do they affect the individual at the current time, but the effects persist. 

Second, while Cottrell et al.'s theory offers some explanatory evidence for the racial gap in cognitive testing, the findings also raise other questions. What can be done past the 54 month mark to reverse these effects? Are early childhood interventions possible to address potential gaps before they materialize? What are systemic remedies to address potential gaps in early childhood, through adolescence, and into adulthood? And, in returning to an original assumption, are the tests measuring what we think that are across all groups? These are important questions to pursue. 


* Cottrell, J. M., Newman, D. A., & Roisman, G. I. (2015). Explaining the Black–White gap in cognitive test scores: Toward a theory of adverse impact. Journal of Applied Psychology, 100, 1713-1736.