New research finds that white Americans are more likely to hold unconscious racism against black Americans if their home region was once heavily dependent on slavery.

A crowd of students in Birmingham, Alabama, flying the Confederate flag in opposition to the start of the Birmingham Campaign in May of 1963. (Photo: Frank Rockstroh/Michael Ochs Archives/Getty Images)

Racial bias is often discussed in psychological terms—as a defense mechanism, a product of emotional immaturity, a way to project one's fears and insecurities onto others.

But what if the causes of racism, and potential solutions, are more a matter of one's environment? Could a region's long history of racism create social and economic disparities that trigger prejudiced thoughts?

That intriguing question is raised in a new study, which finds a strong link between a region's racial legacy and the implicit, or unconscious, bias of its current-day inhabitants.

Among white residents, "counties and states more dependent on slavery before the Civil War display higher levels of pro-white implicit bias today," a research team led by University of North Carolina psychologist B. Keith Payne writes in the Proceedings of the National Academy of Sciences.

To Payne and his colleagues, their findings suggest that this subtle but pernicious brand of bias "may be better understood as a cognitive manifestation of historical and structural inequalities" than as something that is "solely a feature of individual minds."

The researchers utilized two fascinating and very different sets of data: the 1860 Census, which, for each county in America, recorded the percentage of the population that consisted of slaves; and modern-day scores of unconscious bias recorded at the Project Implicit website, which offers tests designed to measure latent prejudice.

Matching the two lists, the team finds that William Faulkner was right when he declared: "The past isn't dead. It isn't even past."

"Counties and states with a higher proportion of their populations enslaved in 1860 had greater anti-black implicit bias among white residents," the researchers report. Intriguingly, they also found that, for whites, unconscious bias "was associated with [1860] slave populations, but not with modern black populations."

Now, that association could reflect a simple transfer of cultural norms—in this case, racism—from one generation to the next. But Payne and his colleagues argue there's more going on. They report that counties and states with a greater percentage of slaves 160 years ago have higher levels of racial segregation today, as well as a higher proportion of blacks living in poverty. Further analysis revealed that such conditions are linked to implicit bias.

"Structural inequalities cue biased thoughts, which may in turn lead to greater inequalities," the researchers write. In other words, a racist culture leaves black Americans less well-off, which triggers toxic assumptions among local whites that people of color are less intelligent, skilled, or hard-working than more-advantaged groups.

If the researchers' thesis is correct—they concede the evidence isn't definitive—it suggests we might need a new approach to combating racism. The researchers argue that "more attention should be given to modifying social environments, as opposed to changing the attitudes of individuals."

But that's a long-term project. Perhaps more doable on the short-term is developing a curriculum in which youngsters of all races learn about the structural, historical, and institutional bases of racial inequality. Taught early enough, and emphasized often enough, such knowledge could serve as a counterweight to our deep, destructive tendency to categorize and judge.