Racism is the wrong term to use but it is an interesting study nonetheless.
---
Snip
Trusting people essentially means assuming they are what they seem to be, which, if we don’t actually know the person, can lead us to rely on stereotypes. It’s a form of complacency. Not trusting someone means we’re not sure if a person is what they seem to be or not, and that makes us pay close attention to the actual information we have rather than vague generalities.
The Dutch psychologist Carsten K.W. De Dreu has found that oxytocin, the so-called “love hormone” that drives mothers to bond with their newborns and may play a role in romantic love, also has the effect of making people more ethnocentric. People given doses of oxytocin, he found, tended to discount the value of the lives of those of different ethnicities. The impressive human capacity for connection and cohesion, in other words, is difficult to disentangle from the tendency to create an out-group against which to unite.
http://www.businessweek.com/articles...inked-to-trust