Over the years it has emerged that seeing the pain of another person makes people's nervous system respond in the same way it would if they were feeling that pain themselves.
Now, researchers claim that this kind of empathy is diminished when people (black or white) who hold racial biases see that pain is being inflicted on those of another race.
People apparently continue to respond with empathy when pain is inflicted on people who don't fit into any preconceived racial category-in this case, 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."
In the study, conducted in Italy with people of Italian and African descent, participants were asked to watch and pay attention to short films depicting needles penetrating a person's hand or a Q-tip gently touching the same spot while their empathetic response was monitored. (The researchers specifically measured a feature known as sensorimotor contagion, as indicated by changes in the corticospinal reactivity assessed by transcranial magnetic stimulation.)
The results showed that people watching the painful episode responded in a way that was specific to the particular muscle they saw being stimulated when the film character was of the same race. But those of a different race didn't evoke that same sensorimotor response.
In further studies, the researchers tested individuals' responses to pain inflicted on models with violet hands. Under those circumstances, participants' empathetic responses were restored.
Alessio Avenanti of the Universit' di Bologna, said: "This default reactivity of human beings implies empathy with the pain of strangers (i.e., a violet model) if no stereotype can be applied to them.
However, racial bias may suppress this empathic reactivity, leading to a dehumanized perception of others' experience."
The new findings expand on previous studies that have primarily looked at the neural underpinnings of racial bias based on facial expressions, thus emphasizing people's emotional reaction to the pain of others, the researchers said.
The researchers explained: "To the best of our knowledge, our study is the only one that has tested the reactivity to hands and thus hints at the existence of general processes for separating the self from the others that may be largely independent from specific emotions."
Based on the findings, the researchers suggest that methods designed to restore empathy for people of other races might also help in dealing with racial prejudice.
The study has been published in Current Biology, a Cell Press publication.