Why is President Barack Obama — the son of a white mother from Kansas and a black father from Kenya — considered a black man?

While historic, social, political and more sinister factors almost certainly influence the prevailing view of the president’s race, a new study co-authored by a University of California, Davis, researcher has found that a basic learning pattern also is involved.

People learn about new things — such as diseases, dogs or cars — by noting attributes that distinguish them from the same types of things that they already know, past research has shown.

The new study by UC Davis psychology professor Jeffrey Sherman and two colleagues demonstrated for the first time that the same basic learning pattern also applies when people place others into ethnic categories based on facial characteristics.

“Features that are more typical of minority group members draw more attention,” Sherman explained. “So, when someone has a mixture of features, the minority features are the ones that we tend to grab onto. We pay more attention to them and they are used more heavily in our judgments. They influence us to a greater degree.”

The study — published today in the online edition of Psychological Science — was conducted by Sherman; lead author Jamin Halberstadt, a psychology professor at the University of Otago in New Zealand; and Steven Sherman, a professor of psychological and brain sciences at Indiana University and Jeffrey Sherman's father.

The study looked at two groups: Chinese people who had grown up in China or elsewhere as part of a majority Asian population and Caucasian New Zealanders.

When shown a series of computer-morphed faces with both Asian and Caucasian features, the Chinese group tended to identify ambiguous faces as Caucasians, and the Caucasian group tended to identify ambiguous faces as Asian.

To control for sociopolitical and other variables, the researchers ran a second test in which the two groups were shown just two different faces. But they were shown one much more often than the other. For example, the groups were shown two different Caucasian faces, although they saw one of the two faces three times more than the other.

“We made the one face the majority face and the other the minority face,” Sherman explained.

When the two faces were morphed together, participants were more likely to categorize the result as the minority face. This again shows that features of the minority face are given more weight in an ambiguous situation, Sherman said.

Thus, while motivational, political, sociological and economic factors may play a role in the assignment of mixed-race individuals to minority groups, they are not necessary for that to occur, the researchers wrote.

The study, Sherman said, showed that the phenomenon “could be based on a very basic and general cognitive process of how we learn to distinguish things from each other — one kind of dog from another dog, one kind of disease from another disease, one kind of car from another car.”