Zuo and Han (2013) measured relative empathy responses for Chinese people who had lived in the US most of their lives using a series of 48 video clips of white and Chinese people (gender and race numerically balanced) being poked in the cheek with a cotton swab or a needle while wearing a neutral expression. Participants had to press one button to say that the person was feeling pain or a different button to say that they were not feeling pain. This happened very quickly to try to measure the subconscious response.
They found no significant difference in response times, nor in the fMRI signal intensity, despite the overall trend of own-race bias found in many adults. They conclude that living in the US has increased the subjects' ability to empathize with the majority race. I further imagine that as the subjects have the perspective of the majority pressed on them at every turn, they are forced to perform the cognitive empathy task of perspective-taking, and over time this builds up their emotional empathy responses as well.
Cao, Contreras-Huerta, McFadyen, and Cunnington (2015) built on this by measuring relative empathy responses via fMRI for Chinese students living in Australia using videos of white and Chinese faces being touched with a cotton swab or a needle. They found that increased levels of contact are related to increased levels of empathy. Further, the kind of contact that is most predictive is incidental contact -- just seeing white faces around you.
Consider this in the inverse: empathy is decreased when you are never forced to take the perspective of someone else, and when you never see them around you in large numbers. When you do not consume any media by and about people of color, you automatically have less empathy for people of color. When you do not ever experience being in a majority-female space, you automatically have less empathy for women. If you want to be empathetic to people who experience oppression you do not, you have to change what you see and where you go.
[references]Zuo, X. and S. Han. 2013. "Cultural experiences reduce racial bias in neural responses to others’ suffering." Culture and Brain 1, 34-46. http://dx.doi.org/10.1007/s40167-013-0002-4
Cao, Y.; L. S. Contreras-Huerta; J. McFadyen; and R. Cunnington. 2015. "Racial bias in neural response to others' pain is reduced with other-race contact." Cortex: A Journal Devoted To The Study Of The Nervous System And Behavior 70, 68-78. PsycINFO, EBSCOhost.