Australasian Science: Australia's authority on science since 1938

Racial Classification Isn’t Black and White

By Stephen Luntz

People are more likely to classify faces showing a mixture of characteristics into a category they have had less exposure to, a University of Otago study has found.

The research sheds light on why biracial individuals such as US President Barack Obama are considered part of a minority.

A tendency to view people who fall between categories as “others” might be explained by a subconscious desire to keep the group with which one identifies pure. The complex politics of race provide other reasons for classifying individuals with mixed heritage as a minority, such as to deny privileges. However, A/Prof Jamin Halberstadt says: “I think the burden of proof falls on the motivational explanations”.

Halberstadt and American colleagues Steven and Jeffrey Sherman showed people photographs of six individuals, and assigned these randomly to three categories called red, yellow and blue. Participants had to learn which two fitted into each so-called colour.

Having learnt to do this, the participants were told that the category involved two subtypes, exemplified by the two individuals whose images they had seen. They were then shown photographs formed by blending the faces of the two members of a category and asked which subtype the blended photograph fell into. These blended images were consistently more likely to be categorised with whichever individual had been shown less frequently.

The results are consistent with other studies of cognitive learning. For example, Prof John Kruschke of the University of Indiana has shown that when people encounter someone with symptoms associated with two different diseases they are more likely to suspect the presence of the disease they have seen less often, even though logic might suggest that the more frequently sighted disease was more likely.

It is unclear why we do this. Certainly it is hard to explain an evolutionary advantage to the strategy. “Evolution doesn’t always optimise,” Halberstadt says. “Any benefits from categorising correctly may be outweighed by a capacity to make judgements quickly.”

Obama’s election may have stimulated research into racial categorisation. In a separate study Dr Kevin Brooks and Scott Gwinn of Macquarie University asked participants to categorise morphed images by race. Despite the widespread use of the terms black and white, they found that facial morphology played a larger role than skin tone in determining whether a photograph was deemed to be African or European.