Normally when you see or imagine someone else in pain, your brain experiences a twinge of pain as well. Not so when race and bias come into play, scientists now find.

Intriguingly, people respond with empathy when pain is inflicted on others who don't fit into any preconceived racial category, such as those who appear to have violet-colored skin.

"This is quite important because it suggests that humans tend to empathize by default unless prejudice is at play," said researcher Salvatore Maria Aglioti, a cognitive and social neuroscientist at the Sapienza University of Rome in Italy.

Scientists asked volunteers in Italy of Italian and African descent to watch short films showing either needles penetrating a person's hand or a Q-tip gently touching the same spot. At the same time, they measured brain and nervous system activity.

When the volunteers saw the hands get poked, the brain and nervous system activity revealed the same spot on each volunteer's own hands reacted involuntarily when the person in the film was of the same race. Those of a different race did not provoke the same response.

However, when both white and black volunteers saw violet-colored hands get jabbed, they responded empathetically. This suggests that people normally automatically feel the pain of others, and the lack of empathy that volunteers showed for people of other races was learned and not innate.

"This default reactivity of human beings implies empathy with the pain of strangers," said researcher Alessio Avenanti of the University of Bologna in Italy. "However, racial bias may suppress this empathic reactivity, leading to a dehumanized perception of others' experience."

It could make evolutionary sense that we feel less empathy for people who are different than us. "In case of war or even a friendly competition like a football game, it could be adaptive to feel less empathy for people we consider our opponents," said social neuroscientist Joan Chiao at Northwestern University in Evanston, Ill., who did not take part in this research.

Then again, "it also makes evolutionary sense for us to feel the pain of others, as it might cue that there is danger close by," Chiao noted. "Also, without feeling the pain of others, it could be harder to motivate altruistic behaviors, especially if such behaviors come at a cost."

Essentially, for the stranger in pain, in order to elicit help, he or she would need to actually get the stranger to feel empathy.

While the ability for culture to regulate empathy could be helpful, "when you feel prejudices that are not adaptive, that are not rooted in reality, that shows that there can be a darker side to empathy regulation," Chiao added.

These new findings could suggest one could help deal with racial prejudice with methods designed to restore empathy for others, the researchers said.

"One can reduce empathy, but one can also promote it, learning positive associations with another group," Chiao said.

The scientists detailed their findings online May 27 in the journal Current Biology.