Using a mouse-tracking analysis, researchers found that even when users decided a man dressed as a janitor was white, the speed and path in which they moved their mouse to the “white” button was slower and veered closer toward the “black” button than when the same man was dressed in a business suit. The more racially ambiguous the face, the more pronounced the results.

“We tend to think that our perception of a face depends on their facial features, but what we found is that the cues around the face and the stereotypes we bring to the table influences our perception of race,” said the lead author, Jonathan B. Freeman, a doctoral candidate in psychology at Tufts.

Social status may not be the only variable informing our perceptions of a person’s race. “Although we have suggested that the effects of contextual cues on race categorization were driven by differences in the social status of occupations,” the study says, “it is possible that they were driven by other differences related to occupations, such as stereotypes of intelligence, pay, or who does ‘dirty work.’ ”

Of course, there’s the question of whose perceptions are being judged. The participants, all undergraduates, were overwhelmingly white. There were some Asians and South Asians and one person who self-identified as biracial, but there were no African-Americans or Hispanics, a reflection of the university population that volunteered to participate. The researchers are planning a follow-up study that will examine whether black or multiracial individuals perceive race in a similar way, Mr. Freeman said.