We tend to be worse at telling apart faces of other races than those of our own race, studies have found. Now research shows some people are completely blind to features that make other-race faces distinct. Such an impairment could have important implications for eyewitness testimony in situations involving other-race suspects.

The ability to distinguish among members of one's own race varies wildly: some people can tell strangers apart effortlessly, whereas others cannot even recognize the faces of their own family and friends (a condition known as prosopagnosia). Psychologist Lulu Wan of the Australian National University and her colleagues wanted to quantify the distribution of abilities for recognizing other-race faces. They asked 268 Caucasians born and raised in Australia to memorize a series of six Asian faces and conducted the same experiment, involving Caucasian faces, with a group of 176 Asians born and raised in Asia who moved to Australia to attend university. In 72 trials, every participant was then shown sets of three faces and had to point to the one he or she had learned in the memorization task.

The authors found that 26 Caucasian and 10 Asian participants—8 percent of the collective study population—did so badly on the test that they met the criteria for clinical-level impairment. “We know that we are poor at recognizing other-race faces,” says Jim Tanaka, a professor of psychology at the University of Victoria in British Columbia, who was not involved in the research. “This study shows just how poor some people are.” Those individuals “would be completely useless in terms of their legal value as an eyewitness,” says study co-author Elinor McKone, a professor of psychology at the Australian National University. The world's legal systems do not, however, take into account individual differences in other-race face recognition, she notes.

One's lifetime level of exposure to other races could factor into a person's ability to recognize people of another color, according to the findings published in the January issue of the Journal of Experimental Psychology: General. Among 106 Asian participants born and raised in Australia, only about 3 percent were blind to Caucasian faces. In comparison, nearly 6 percent of the Asians born and raised in Asia had the impairment.

The effect extends to other races, too. In a study published in 2001 in Psychology, Public Policy, and Law, black people recruited in South African shopping malls, who had average levels of interracial contact, were better at recognizing faces of their own race than of others.