Image caption Researchers suited-up computer generated heads in high and low-brow outfits

What you wear can influence what race others perceive you to be, a new study finds.

Scientists dressed people in either smart business attire or work overalls and asked onlookers to categorise the faces as white or black.

Faces were more likely to be seen as white when dressed smartly and black when in overalls, the researchers found.

The US-based team report their findings in the journal Plos One.

Scientists think that if people are made aware of the strategies they use to evaluate other people, the effects of these subconscious judgements could be lessened.

"This is a really interesting paper testing hypotheses about how we categorise people," said psychologist Lisa DeBruine who studies facial recognition at the University of Aberdeen and who was not involved in the work.

The researchers asked about 20 volunteers to assign men's and women's faces, which ranged in skin tone and outfit, to one of two race categories - white or black.

Black or white?

The team from Tufts University, Medford, Stanford University and University of California, Irvine, found that for the most racially ambiguous faces participants were 6% more likely to see a face as black if the person was wearing overalls rather than a suit.

In other words, the most ambiguous face was categorised as black about 65% of the time when wearing a suit, and 71% of the time when wearing overalls.

By tracking the volunteers' hand movements as they moved a mouse to make their decision, the researchers were able to pick up on momentary hesitations giving them clues to how these decisions were made.

The team found that even if a volunteer decided a person wearing a business suit was black, the trajectory of the mouse tended to deviate a little toward the "white" option more often than when the "black" face was wearing overalls.

Colour blind

"[The results]... imply that our cultural knowledge, and what we are expecting to see stereotypically, can literately change what we do see in other people," said graduate student Jon Freeman from Tufts University, who led the study.

He explained that decisions about race or gender or age change the way we feel about people and affect the way we interact and behave towards them.

Mr Freeman and his colleagues are planning to look to see if the influence of clothing on race perception disappears when people are made aware that "the baggage that [they] bring to the table might actually alter how race is perceived".

If this is the case, studies like these could help alleviate the effects of stereotyping.