Category: Cognitive Ability

The scope of racial disparities in test scores in the United States

The purpose of this post is to provide a comprehensive overview of racial and ethnic disparities on cognitive and academic tests in the United States. The primary focus is on black and white Americans because most data focuses on comparing these groups, but I’ll also mention disparities for other groups (mainly Hispanics and Asians) when such data is available. I start by reviewing data on the magnitude of racial disparities in cognitive ability. Next, I consider racial disparities in other kinds of tests, including college admissions and academic achievement tests, finding that these disparities are about as large as disparities in cognitive ability. Then, to better contextualize the magnitude of racial disparities in test scores, I compare racial gaps to gaps between other groups, such as students from different countries or different levels of socioeconomic status. Finally, I present data on the ubiquity of test score gaps, showing that the gaps persist through all levels of education, across all geographical units of analysis, and across all socioeconomic levels.

The causal influence of cognitive ability

In a previous post, I cited data showing that cognitive ability is significantly correlated with various important outcomes, such as academic achievement, occupational performance, socioeconomic status, anti-social behavior, and health. However, that data only establishes that there is a statistical association between cognitive ability and these outcomes. The data does not establish that cognitive ability has a causal influence on any of these outcomes. In this post, I will provide evidence that cognitive ability has a causal influence on academic achievement, occupational performance, socioeconomic success, and anti-social behavior.

The predictive validity of cognitive ability

There is overwhelming evidence showing the predictive validity of cognitive ability for important life outcomes. Cognitive ability measured as early as age 6 has a strong association with one’s future success in a number of important outcomes, including academic achievement, occupational performance, income, educational attainment, occupational prestige, criminality, self-control, and health. The associations are typically large, often making cognitive ability the best predictor for such outcomes. In this post, I will cite research showing this evidence. I will begin with some background on cognitive ability, including definitions, the distributions of IQ test scores, the stability of cognitive ability test scores, and expert consensus on the validity of cognitive ability. Finally, I will cite data demonstrating the predictive validity of cognitive ability in academic achievement, occupational performance, socioeconomic success, anti-social behavior, and health.

The predictive validity of cognitive ability (OLD)

There is overwhelming evidence demonstrating the undeniable predictive validity of cognitive ability. Cognitive ability measured as early as age 6 has a strong association with one’s future success in a number of important outcomes, including income, educational attainment, academic performance, occupational prestige, occupational performance, criminality, etc. These associations are robust, persisting even after controlling for a number of plausible confounding variables, including parental socioeconomic status, race, job training and job experience, and other risk factors for the relevant life outcomes. The totality of evidence heavily implies that this association is causal, indicating that early cognitive ability is a powerful factor in determining a person’s chances of achieving conventional measures of success in Western societies.

The black-white cognitive ability gap and social outcomes

Most people are aware that there are significant disparities between blacks and whites in the United States with regard to a wide range of important social outcomes, including crime, income, education, poverty, welfare usage, etc. For almost every measurable metric of important life outcomes, blacks perform significantly worse than whites. In this post, I will cite studies showing that many of these disparities are likely caused by the significant cognitive differences between blacks and whites. I begin by illustrating a few examples of the disparities between blacks and whites with respect to important life outcomes. Then I briefly review evidence demonstrating the predictive validity and causal influence of cognitive ability for these outcomes. Next, I present data illustrating the scope and magnitude of the black-white cognitive ability gap. Finally, I provide evidence indicating that many of the aforementioned disparities between blacks and whites are (mostly) eliminated after controlling for youth cognitive ability.

Poor environmental explanations of the black-white cognitive ability gap

In this post, I will consider some of the most commonly posited explanations of the black-white cognitive ability gap. Firstly, I consider what I call the Test Bias Hypothesis, which posits that black-white differences in cognitive test scores are the result of biased tests rather than genuine differences in cognitive ability. Secondly, I consider the Schooling Hypothesis, which holds that the cognitive ability gap is the result of differences in schooling between blacks and whites. Finally, I consider the Socioeconomic Hypothesis, which affirms that the cognitive ability gap is the result of the SES gap. I will argue that each of these hypotheses fail to adequately account for the cognitive ability gap. The predictions made by each of these hypotheses (insofar as they make predictions) are consistently falsified by the preponderance of data.

Studies attempting to explain the black-white cognitive ability gap

In this post, I will review studies that have attempted to account for the cognitive ability gap among children by controlling for a variety of factors, including parental socioeconomic status (SES), birth weight, home environment, parenting practices, etc. I will use these studies to determine what seem to be the most plausible candidate explanations of the gap. I end by reviewing some important issues for future investigation.

Genetics and the black-white cognitive ability gap

I began investigating potential investigating possible environmental causes of the cognitive ability gap in another post. I argued that common environmental explanations – test bias, schooling, socioeconomic status, and societal racism – failed to explain the gap. Because common environmental explanations fail, it may prove useful to consider non-environmental (i.e. genetic) explanations of the gap. I will perform this task in this post. First, I will clarify the meaning of estimates of the heritability of intelligence. Next, I criticize some common poor arguments against genetic explanations of the gap. Then I will consider some arguments for a genetic explanation of the gap that are related to the heritability of intelligence. I conclude that such arguments are not sufficient to make any conclusion either way about the cause of the gap. I end by detailing the kinds of direct data that should be used to confidently conclude whether and to what degree the cognitive ability gap is due to genetic differences.

The cognitive ability of blacks raised by non-blacks

In a previous post, I argued that the black-white cognitive ability gap is responsible for many of the undesirable social disparities that we find between blacks and whites in the United States – including disparities in income, education, occupation, and crime. This means that the cause of the cognitive ability gap is extremely important, as this informs how (and if) we can reduce these social disparities. In another post, I examined some arguments on whether the gap is due to genetic differences or environmental differences. In that post, I concluded that we must use direct data to quantify the degree to which the black-white cognitive ability gap is due to genetic differences vs environmental differences. In this post, I will attempt to review all such direct data. I conclude that a primarily environmental explanation of the gap is most compatible with all the relevant direct data.