Humans experience a real physical response to observed sensation in other humans. The strength of this response differs in degree between people, but is also seen to be suppressed when the observed sensation occurs to a person understood to be in a racial out-group. This suppression is actually strongest when it is a racial out-group that is known to exist, rather than a purple or green person.
In a phenomenon known as the “enfacement illusion” a person can be made to internalise another person’s face as if they were seeing their own face in a mirror. While in the short term this is fascinating, researchers have also observed that this can have a lasting impact on how the subject thinks they actually look.
The implicit association test (IAT) has come under fire as a means with which to judge “implicit bias”. While taking this criticism seriously we can still at least find curiosity in the fact that in a study in which white subjects were run through the “rubber hand illusion” with a black hand, their subsequent scores in the IAT showed less bias.