For some reason, I decided that my Research Methods class would gain by a discussion of the phenomenon of regression to the mean. In hindsight, it didn’t connect to the rest of the material that well. I think I was just captured by this quote from Danny Kahneman. I’m excepting it here from wikipedia (Regression toward the mean) which is excerpting it from his biography, although I saw some part of the quote elsewhere that made me go looking for the original.

The first part of the quote is actually about a curious consequence of the regression to the mean phenomenon:

I had the most satisfying Eureka experience of my career while attempting to teach flight instructors that praise is more effective than punishment for promoting skill-learning. When I had finished my enthusiastic speech, one of the most seasoned instructors in the audience raised his hand and made his own short speech, which began by conceding that positive reinforcement might be good for the birds, but went on to deny that it was optimal for flight cadets. He said, “On many occasions I have praised flight cadets for clean execution of some aerobatic maneuver, and in general when they try it again, they do worse. On the other hand, I have often screamed at cadets for bad execution, and in general they do better the next time. So please don’t tell us that reinforcement works and punishment does not, because the opposite is the case.”

The second part is what really stuck in my mind, though (this is still Kahneman reporting the incident in his bio):

This was a joyous moment, in which I understood an important truth about the world: because we tend to reward others when they do well and punish them when they do badly, and because there is regression to the mean, it is part of the human condition that we are statistically punished for rewarding others and rewarded for punishing them. I immediately arranged a demonstration in which each participant tossed two coins at a target behind his back, without any feedback. We measured the distances from the target and could see that those who had done best the first time had mostly deteriorated on their second try, and vice versa. But I knew that this demonstration would not undo the effects of lifelong exposure to a perverse contingency.

What he’s describing here is one of the dark sides of automatic, statistical habit learning.  There might be anomalous contingencies in the real work (e.g., yelling at people seems to work due to regression to the mean) and we pick up these tendencies and they become ingrained due to our automatic statistical learning mechanisms.  Implicit stereotypes (bias, prejudice) probably occur by roughly the same mechanism.

P.S. There’s some sort of clever joke/pun about regression, habits and being mean that could be derived from the title, but I don’t quite see how to make it pithy, so it is left as an exercise for the reader.