The diving bias

England have lost on penalties at five of the nine last major international football championships. So here's some interesting news for whoever picks up the poisoned chalice from Steve McLaren—after analysing hours of footage, a team of psychologists in Israel have discovered the optimum strategy for a goalkeeper facing a penalty: don't move. The team found that keepers who stayed in the centre of the goalmouth saved roughly a third of the penalties they faced, while those jumping to the left or right saved no more than one in eight.

Yet in 94 per cent of the penalties watched by the researchers, the keeper chose to dive left or right. Why do so few choose to follow the optimal strategy? The researchers attribute the failing to a cognitive bias; specifically the well-known omission bias. The effect of the omission bias is that following some kind of negative outcome—like letting in a penalty—we feel worse if we did nothing to stop it happening than if we did something.

This has a superficial plausibility—the effects of cognitive biases on our behaviour can be very powerful, even in instances when they would seem to work against our interests. Yet we are not slaves to our biases, and when the dividend that would accrue from overcoming one—such as a goalkeeper more than doubling his chances of saving a penalty—is sufficiently high, one would expect the motivation to be there.

Perhaps the explanation has more to do with football's traditional antipathy to stats-based analysis. In stark contrast to baseball, where some managers have managed to revolutionise their team's performances by basing team selections and match tactics on particular statistics, football seems to have little time for number-crunchers. TV pundits and newspaper reports hurl statistics at us, but rarely make serious attempts to think through the tactical implications of the numbers they produce.

So in three years' time in South Africa—assuming England make it through—let's hope to see a little bit less movement from our keepers when they face the inevitable spot-kicks.