I found the whole NBA referees have unconscious racial bias! thing totally uninteresting until Dan Shanoff’s blog alerted me to a fascinating aspect:

Mr. Wolfers said that he and Mr. Price classified each N.B.A. player and referee as either black or not black by assessing photographs and speaking with an anonymous former referee, and then using that information to predict how an official would view the player. About a dozen players could reasonably be placed in either category, but Mr. Wolfers said the classification of those players did not materially change the study’s findings.

Oddly enough, I think this might be one moment when “race” does actually correlate fairly clearly to skin color. I would imagine (from a point of complete ignorance) that a referee, acting quickly and immediately, has little time to consciously identify a player before blowing the whistle. It would be the color of the limbs doing the action that plays the key role here, I expect.