Beware of Hindsight Bias

The book "Future Babble", which I'm just finishing at the moment, mentions a new type of cognitive bias that I had not heard of before: hindsight bias. This can be seen, for example, when fans say after a match that the outcome was inevitable, say, as a result of the tactics used by the manager or his player choices.

The bias is not simply that people become more convinced after-the-fact that this outcome was always going to occur. People actually become more convinced that they knew beforehand that this was going to happen. Numerous experiments, comparing people's memories of their certainty with recordings made before the event, have shown this effect to be quite strong.

Further experiments showed that typical post-match analysis actually makes this bias worse. Two psychologists from Northwestern University studied fans at American college football matches and asked some of them to analyze the match in certain ways. (Their paper is called "Perceptions of Purple: Counterfactual and Hindsight Judgments at Northwestern Wildcats Football Games" in case you want to look it up.)

Before the match, fans gave what would be the actual outcome of the match a less than 15% chance of occurring. After the match, fans recalled their own predictions were of a 30% chance of occuring. Amazingly, fans who were asked to analyze the match — in terms of what could have been done differently or what caused the result — recalled their own predictions were higher than 50%!

Clearly, most fans who think about football as much as we do are doing exactly the sort of analysis performed in the experiment. Hence, we are quite likely to fall victim to hindsight bias.

In my mind, this highlights once again the importance of looking at football statistics. Of course, statistics can't eliminate hindsight bias, but they can do two things.

First, they can suggest that some inevitability arguments are implausible. For example, a claim that the team lost because one player started in place of another would seem suspect if statistics show the one who played created just as many chances, had just as many successful tackles, etc. as would have been predicted for the other player.

Second, and perhaps more importantly, statistics can remind you that football involves a lot more chance than most people are willing to admit.