The trend is a familiar one, documented across grade levels: Black students are disciplined more harshly than their white classmates. They’re about four times as likely to be suspended and almost twice as likely to be expelled. The pattern also extends to the youngest black learners. Federal education data released in June revealed black preschoolers were 3.6 times more likely to receive one or more out-of-school suspensions. Yet even with this recurring outcome, one aspect remained largely unknown: What was the major contributing factor in the highly disproportionate suspension and expulsion rates for black pre-k children?

A new study from the Yale Child Study Center, a leader in early-childhood research, set out to address this perennial question and answer why black children make up an overwhelming share of the youngsters pushed out of preschool. Multiple studies show that implicit bias—harboring unconscious stereotypes that shape educators’ behaviors and decisions—influences teacher expectations and gifted-and-talented placements for older schoolchildren. The link was missing, however, in early-childhood settings.

In what’s believed to be a first-of-its-kind analysis, Walter Gilliam, a Yale professor and noted expert in preschool discipline, discovered both black and white early-childhood educators showed signs of implicit bias in administering discipline, seemingly rooted in different, though equally harmful, race-based judgements. “Implicit biases do not begin with black men and police,” Gilliam said. “They begin with young black boys and their preschool teachers, if not earlier.”

Using a sophisticated eye-tracking system, a sensor technology that follows and records the movement of a person’s gaze, Gilliam and the research team invited pre-k teachers to watch a dozen short video clips of preschoolers in typical classroom situations. Participants were asked how quickly and accurately they could detect challenging behaviors in the children—a black boy, black girl, white boy, and white girl—yet none of the videos contained misbehavior, and the children in the videos were all actors. What researchers found was that the preschool staff—both black and white teachers—more closely observed black youngsters, and especially black boys, when challenging behaviors were expected, “suggesting that preschool teachers may hold different expectations based on the race of the child,” said Gilliam.

In a second segment of the research, the same group of preschool educators were asked to read a paragraph detailing “unpredictable and challenging” classroom behaviors, ranging from difficulties napping and following instructions to blurting out answers and taunting other children. Each vignette contained a pre-selected, stereotypical black or white boy or girl name: DeShawn, Jake, Latoya, and Emily. The participants were then asked to rate the severity of the behavioral challenges—the only difference in each vignette was the perceived race and sex of the child—and the likelihood that they would recommend suspension or expulsion.

Of note, both black and white preschool educators—22 percent of the participants identified as black, 67 percent as white—showed strong evidence of implicit biases. However, the nature of the biases differed based on the race of the teacher. White teachers appeared to have lower expectations of black children, finding them as a group more prone to misbehavior, “so a vignette about a black child with challenging behaviors [was] not appraised as … unusual, severe, or out of the ordinary.”

Conversely, black teachers seemed to hold black preschoolers to a higher behavioral standard; pay notably more attention to the behaviors of black boys; and recommend harsher, more exclusionary discipline. Prior research suggests that teachers of all races tend to over-punish black students. Gilliam also points to research on black parents and their “need to prepare [black] children for, or protect them from, a harsh world” to help explain this tendency. “It seems possible that the black preschool teachers may be operating under similar beliefs … that black children require harsh assessment and discipline.” The study further finds the consequence is significant, as black early educators are more likely to teach in communities with higher proportions of black preschoolers: “Greater scrutiny of black students … may contribute to the increased likelihood of preschool expulsions and suspensions with black children, and black boys more specifically.”

Similarly, when the preschool educators learned the students’ family background, to offer some context for the “behavioral challenges,” the responses also diverged based on race. When the race of the teacher and the child were the same, there was greater empathy for the child; when the race of the teacher and the child differed, the additional family information led teachers to perceive the child’s behavior as more severe.

While one of the strengths of the study is its reliance on 132 participants at a widely attended annual early-education conference, the researchers caution that this can also be a limitation—many preschool teachers work for very low wages or for programs without the resources to send them to such professional-development opportunities, Gilliam admits, conceding the possibility that “this sample may not be typical preschool teachers.”

Even so, the University of Pennsylvania professor Howard Stevenson said the Yale study gives greater context to existing data regarding preschool suspensions and expulsions. Stevenson, who has studied and written on racial literacy, called it “groundbreaking work” that helps to address a gnawing issue that parents of preschoolers of color often ask in his research, which is how their children are misperceived just by being themselves.

"Racial socialization is the degree to which family or media or parents in particular prepare their children for a world that might be racially difficult,” Stevenson explained. “What [the Yale study] points to is that teachers are already socialized, regardless of their racial background, about racial politics in ways that they don't often understand, but that may come out in their observation of children, and particularly black males.”

Better pre-service training for preschool teachers focused on evidence-based strategies for reducing bias surfaced as a solution to the entrenched problem, as did the importance of ongoing training for veteran educators.

“Early educators are not immune to implicit biases. No one is,” said Gilliam, the lead researcher. But by recognizing the harm these prejudices have on children they serve, preschool teachers “represent perhaps our nation's best frontline defense against the negative impacts of implicit biases.”