A study of hundreds of penalty shootouts at international soccer tournaments reveals that goalkeepers tend to dive the opposite way from the previous kick
If the German national soccer team progresses to the knockout stages of Euro 2016, statistics suggest a clear plan of action in the event of a penalty shootout: “Each player should put the ball in the same corner as the teammate before him,” says Ulrich Schmidt, a behavioral economist at the Kiel Institute for the World Economy (IfW). Together with IfW economist Sebastian Braun, Schmidt analyzed over 350 penalty shootouts in international soccer tournaments. The results were conclusive: “The probability that a goalkeeper will dive the opposite way from the previous kick is significantly higher—55 percent on average—than the probability he will dive the same way,” says Schmidt.
The aim of the study was to discover whether the goalkeeper or penalty taker in a penalty shootout is subject to the “gambler’s fallacy,” i.e., the mistaken belief that the probability of a certain event is dependent on the frequency of its past occurrence. A typical example of the gambler’s fallacy is the assumption that after repeated tosses of a coin resulting in an uninterrupted sequence of heads, the probability of throwing heads again is lower than the probability of throwing tails. In fact, the probability of either outcome remains 0.5—regardless of previous results.
Criticism of previous study on goalkeeper behavior
A previous and much-discussed behavioral economics study found that goalkeepers were subject to the gambler’s fallacy during penalty shootouts. According to that study, after three penalties had been placed in the same corner, there was a higher probability that the goalkeeper would move the opposite way. This conclusion is not shared by Schmidt and Braun, however, who conducted a further 650 penalty shootouts as a laboratory experiment. In fact, there was no evidence of the gambler’s fallacy in goalkeeper behavior either during real-life shootouts or under perfect laboratory conditions. In the latter case, Schmidt and Brown also excluded the possibility of a shot being kicked at the center of the goal as well as the ability of top players to “read” the goalkeeper’s movements during the run-up and then place the ball in the empty corner. Having said that, there is evidence for a systematic pattern of goalkeeper behavior that kickers could exploit.
The study was published in the Current Biology Magazine and can be made available upon request.