"Unarmed black men are disproportionately more likely to be shot and killed by police, and often these killings are accompanied by explanations that cite the physical size of the person shot," said lead author John Paul Wilson, PhD, of Montclair State University. "Our research suggests that these descriptions may reflect stereotypes of black males that do not seem to comport with reality."

Wilson and his colleagues conducted a series of experiments involving more than 950 online participants (all from the United States) in which people were shown a series of color photographs of white and black male faces of individuals who were all of equal height and weight. The participants were then asked to estimate the height, weight, strength and overall muscularity of the men pictured.

"We found that these estimates were consistently biased. Participants judged the black men to be larger, stronger and more muscular than the white men, even though they were actually the same size," said Wilson. "Participants also believed that the black men were more capable of causing harm in a hypothetical altercation and, troublingly, that police would be more justified in using force to subdue them, even if the men were unarmed."

Even black participants displayed this bias, according to Wilson, but while they judged young black men to be more muscular than the young white men, they did not judge them to be more harmful or deserving of force.

In one experiment, where participants were shown identically sized bodies labeled either black or white, they were more likely to describe the black bodies as taller and heavier. In another, the size bias was most pronounced for the men whose facial features looked the most stereotypically black.

"We found that men with darker skin and more stereotypically black facial features tended to be most likely to elicit biased size perceptions, even though they were actually no larger than men with lighter skin and less stereotypical facial features," said Wilson. "Thus, the size bias doesn't rely just on a white versus black group boundary. It also varies within black men according to their facial features."

黑人不成比例的更容易killed in interactions with police, even when unarmed, according to Wilson, and this research suggests that misperceptions of black men's size might be one contributor to police decisions to shoot. But, he cautioned, the studies do not simulate real-world threat scenarios like those facing actual police officers. More research should be conducted on whether and how this bias operates in potentially lethal situations and other real-world police interactions, Wilson said.

The research was published in theJournal of Personality and Social Psychology. Previous research, also published in this journal, suggested that people view black boys as older and less innocent than similarly aged white boys, and that training and experience can help police overcome racial bias in shoot-don't shoot scenarios.