Researchers found that people were more likely to associate threatening images and words with the faces of young black boys than those of young white boys.
Lead study author Andrew R. Todd, of the Department of Psychological and Brain Sciences at the University of Iowa, and colleagues say their findings indicate that the "perceived threat commonly associated with black men may generalize even to young black boys."
They publish the results of their study in the journal Psychological Science.
Todd says it was a real-life observation that spurred him and his colleagues to conduct the study.
"In this case, it was the alarming rate at which young African-Americans - particularly young black males - are shot and killed by police in the US," he explains. "Although such incidents have multiple causes, one potential contributor is that young black males are stereotypically associated with violence and criminality."
The team notes that previous research has indicated that people are more likely to associate threatening stimuli with the faces of black men than white men, which could lead individuals to incorrectly identify harmless objects as weapons.
For this latest study, Todd and colleagues set out to investigate whether people would apply the same negative associations to the faces of young black boys.
Subjects more likely to link gun images to faces of black boys
In one experiment, the researchers enrolled 64 white college students and presented them with the images of six black 5-year-old boys and six white 5-year-old boys.
In between viewing each face, subjects were shown an image of either a gun or a toy - such as a rattle - and were asked to signal which object they perceived it to be.
The team found that the participants were quicker to associate the images of guns with the faces of black boys than those of white boys. Additionally, subjects were more likely to mistakingly identify a toy as a gun after seeing an image of a black boy.
After viewing images of white boys, however, the participants were more likely to mistakingly categorize guns as toys.
The team enrolled 131 white college students in a second experiment, in which participants were shown faces of black and white adults, alongside the images of tools or a gun.
The results were similar to that of the first experiment; participants were more likely to associate images of guns with black faces - regardless of whether the faces belonged to an adult or a child. What is more, subjects were more likely to mistakingly identify tools as guns after seeing an image of a black adult or child.
Further analysis using a process-dissociation procedure revealed that it was unintentional racial bias that drove participants to associate threatening objects with black faces.
Images of black boys 'appear to trigger thoughts of guns, violence'
In another experiment, instead of being presented with images of tools, toys or guns in between pictures of black or white boys, subjects were shown either threatening or non-threatening words.
The researchers found that subjects were more likely to associate threatening words - such as "violent," "dangerous" and "hostile" - with faces of black boys than those of white boys.
"One of the most pernicious stereotypes of black Americans, particularly black men, is that they are hostile and violent," say the authors. "So pervasive are these threat-related associations that they can shape even low-level aspects of social cognition."
Overall, the researchers say their findings indicate that the negative threat-related bias commonly shown toward black men in the US may extend to black boys. Todd adds:
"Our findings suggest that, although young children are typically viewed as harmless and innocent, seeing faces of 5-year-old black boys appears to trigger thoughts of guns and violence."
The researchers plan to investigate whether the possible racial bias identified in this study also applies to black women and girls.
In December 2014, Medical News Today reported on a study published in BMJ Open that suggested black Americans are twice as likely to be killed by guns than white Americans.