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Why Do the Achievement Gaps Exist?

  1. Explanations

Scholars Provide an Overview of Explanations for Black-White Test Score Gap

Many explanations exist for why black Americans consistently score lower on achievement and intelligence tests than white Americans. Two scholars provide an overview of these explanations.

This reports some of the ideas and findings from the following source:

Jencks, C., & Phillips, M. (1998). The black-white test score gap: An introduction. In C. Jencks and M. Phillips (Eds.),The black-white test score gap(pp. 1-51). Washington, DC: Brookings Institution.

To see other reports that originated from this same citation, go to the bibliography.

Christopher Jencks and Meredith Phillips say that Americans have been aware of a gap in black-white test scores since World War I. They say that while a number of explanations for this gap have been put forward, none of them is completely satisfactory.

Jencks and Phillips review both the theories of why the gap persists and also the research that bears on these explanations.

Four Kinds of Explanations for the Black-White Test Score Gap

Jencks and Phillips describe four kinds of explanations for the test score gap:

  1. test bias
  2. heredity
  3. family background
  4. cultural explanations

Within each type of explanation are different theories. Jencks and Phillips point out that some theories have more research support than others.

Type of Explanation

Different Theories and Research Support

Test Bias

Jencks and Phillips describe four explanations of test bias:

  1. Labeling bias. Labeling bias occurs when tests claim to measure one thing but really measure another. Jencks and Phillips say that most psychologists agree that IQ tests measure developed ability rather than innate abilityalthough the tests supposedly measure innate ability. Because developed ability depends heavily on environmental characteristics, groups that live in disadvantaged environments will score lower. The problem here is over what is being measured.
  2. Content bias. Content bias exists when a test measures knowledge that is relevant only for a particular group. So, for instance, a test that measured knowledge of "white" culture vocabulary would put black students at a disadvantage (assuming that "white" and "black" vocabulary were significantly different). Jencks and Phillips say that most tests do not test familiarity with any particular culture. Also, even on tests not confined to exposure to "white" culture or language (for instance, mathematics) black students still score consistently lower than white students.
  3. Methodological bias. Methodological bias exists when the way the test is given or scored puts one group at a disadvantage. So, for instance, if black students scored lower on the same tests when they were given by white (as opposed to black) testers, we would suspect methodological bias. Jencks and Phillips say that this does not appear to be the case with regard to the black-white test score gap.
  4. Prediction bias. Tests are often used to forecast a student or worker's future performance. Prediction bias would be present if a test, like the SAT, underestimated one group's future performance. However, say Jencks and Phillips, research indicates that black and white students who score the same on the SAT do not perform the same in college. Rather, the SAT appears to overestimate the college performance of black students (blacks in college do worse than whites with the same SAT scores). Research also indicates that black workers get slightly lower ratings from their supervisors than white workers with the same test scores.


Jencks and Phillips say that the argument over the genetic or hereditary component of intelligence has raged throughout most of the twentieth century. Many studies have been done to try to tease out the effects of heredity on intelligence. Jencks and Phillips say that while heredity clearly plays some part, the research is still unclear on just how important it is. They say that research on racially mixed children, research on black children raised in white homes, and research on racially mixed children in other countries provide three tentative conclusions:

  • Black or mixed-race children raised in white households have higher test scores than black or mixed-race children raised in black households.
  • When "black" genes (genes that indicate African descent) are not visible to the naked eye, they do not appear to have much effect. In other words, children who have a black parent, grandparent, or ancestor, but who look white and live within a white community, do not have lower test scores than whites from completely European descent.
  • In America, when black children raised in white homes reach adolescence, their test scores drop (indicating a change in environment rather than a change in the students' innate abilities).

Jencks and Phillips conclude that:

". . . we find it hard to see how anyone reading these studies with an open mind could conclude that innate ability played a large role in the black-white gap." (p. 20)

Family Background

Jencks and Phillips say that trying to tease out family background effects from other kinds of effects is a "statistical nightmare." Family background characteristics are related to many other characteristics and so it is difficult to tell what is really causing the effect. They describe different explanations and the research behind them.

  • Parental schooling. The education gap between white and black mothers has fallen over the course of the twentieth century. Correspondingly, the test gap between their children has closed as well. The effect of mothers' education does not appear to be very large, however. Differences in black and white fathers' level of education appears to have even less impact on their children's test scores.
  • Income effects. White parents tend to make more money than black parents. Does this explain the test score gap? Jencks and Phillips think not. According to research, once parental schooling, test scores, and family background are taken into account, the effects of income differences between black and white parents becomes quite small.
  • Single-parent families. Jencks and Phillips say that the effects of being raised in a single-parent family are "never large enough to be of any substantive importance" (p. 24) once other family characteristics are taken into account.
  • Parenting strategies. "Parenting practices appear to have a sizeable impact on children's test scores," say Jencks and Phillips (p. 24). Even when other family characteristics are taken into account, differences in parenting practices account for between 20% and 25% of the black-white test score gap.
  • Grandparents. Even when black and white parents make the same income, black parents were more likely to have been raised in disadvantaged families. Research shows that the disadvantaged status of black children's grandparents is associated with lower test scores.


Jencks and Phillips describe different cultural explanations for the test score gap.

  • Fear of "acting white." Jencks and Phillips say that an influential article in the mid-1980s found that academically successful black students were disparaged by their black peers for acting "white." So, the argument goes, black students may not try to achieve for fear of being teased by their peers. Jencks and Phillips say that later research casts doubt on the importance of this fear for black students. They say that academically successful white students might also be teased for being "nerds." Being academically successful has both social costs and benefits for black and white students. Also, a study of academically successful students found that blacks tend to benefit from this success more than whites.
  • Getting A's in math was almost completely unrelated to feeling unpopular, being physically threatened, or being put down by other students. Indeed, honor society students were likely to feel more popular and less likely to feel threatened.

    The social costs and benefits of good grades were about the same for black and white students. Indeed, black students seemed to benefit more than their white peers from academic success.
One critique of this research says that while the fear of "acting white" probably does not have much to do with creating the test score gap, it may be important in understanding why black students do not reduce the gap.
  • Stereotype threat. Another explanation says that black students may underperform because they are threatened by the stereotype that blacks are not as "smart" as whites. That is, the anxiety over the stereotype that blacks are not academically successful may impair black students' performance. Jencks and Phillips say that this explanation was supported by an ingenious series of experiments. The study found that when black students were asked to record their race before they took a test, they tended to make lower scores. Black students also made more mistakes when the test was described by the experimenter as testing "verbal reasoning ability." White students' test scores did not change under either circumstance.

Jenks and Phillips say that none of the current explanations tells all there is to know about the black-white test score gap, nor do they all point to a single way of closing that gap. They go on to suggest that the U.S. ought to be conducting large-scale experiments to better understand the black-white test score gap. According to Jencks and Phillips:

"If we did more experiments, we might eventually develop better theories. At present, theorizing about the causes of the black-white gap is largely a waste of time, because there is no way to resolve theoretical disagreements without data that all sides accept as valid." (p.42)

Research Design: Authors Christopher Jencks and Meredith Phillips review theories and research on the black-white test score gap. They also comment on effects of the gap and what things might be done to narrow it.


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