I also dig their clever use of the word ‘sinister’.

I have way too many tabs open with papers to read. I still intend to read that dog poop paper, and I’m 2/3rds of the way through a paper on nervous temperament affecting body temperature in sheep, but Bora posted an article this morning that I had to read right away: A Sinister Bias for Calling Fouls in Soccer.

There are a lot of Americans like myself who only watch soccer during World Cup years, and since we aren’t as familiar with the nuances of the game as the die hards, the subjective refereeing is a foreign concept to us. We are a nation accustomed to instant replays, call challenges, and overturns. We simply don’t understand it when controversial calls are made, or important calls are not made. We can see what really happened (over and over and over again, as sports channels are wont to do), so why is the bad call allowed to stand?

FIFA’s stance on this subject has historically been that human error adds to the drama and pathos of their sport. “Players, coaches and referees all make mistakes. It’s part of the game. It’s what I would call the “first match”. What you see after the fact on video simply doesn’t come into it; that’s the “second match”, if you like. Video evidence is useful for disciplinary sanctions, but that’s all. As we’ve always emphasised at FIFA, football’s human element must be retained. It mirrors life itself and we have to protect it,” said FIFA general secretary Urs Linsi on the subject in 2005.

More recently, in response to the American outrage at referee Koman Coulibaly’s disallowed goal during the USA vs. Slovenia match in this year’s World Cup, FIFA’s head of refereeing Jose-Marcia Garcia-Aranda said, “Some of them are not good decisions on the field of play and this for human beings, is natural. [...] We have excellent decisions on the field of play. Later, maybe with 32 cameras, thousands of people assessing this kind of situation, we realize these decisions were not fully correct.”

ResearchBlogging.orgIt is my understanding that FIFA is reluctant to bring in more technology because they do not want areas of the world that are too poor to afford that technology to be at a disadvantage. If this is the case, then perhaps we can think of ways to eliminate error without the use of additional technology that would sully the ‘humanity’ of the sport. To this effect, Kranjec and colleagues devised an experiment to test whether subconscious visual bias associated with left-to-right reading patterns causes an inherent disparity between the number of fouls called on a play based on the direction of movement.

English language cultures (along with many others) read from left-to-right on the page, which seems to instill a sense of preference and naturalness to left-right motion. Motion from right-left can be subtly and subconsciously jarring or uncomfortable for the viewer, a phenomenon which the authors cite is often exploited by the cinema industry (i.e. having heroes enter from the left but antagonists enter from the right). The authors hypothesize:

Given this bias for representing prototypical events from left-to-right, English speakers should be more likely to call a foul when the direction of play moves leftward. Below awareness, left-moving events should seem atypical and relatively debased compared to right-moving events. For soccer-knowledgeable participants making refereeing judgments in ambiguous situations, this perceptual-motor bias may serve to lower the threshold for calling a foul.

To test this, they recruited members of their university soccer team to examine photographs where two athletes were in a confrontation with clear directionality of movement, where one player clearly had possession of the ball and the other player was clearly the challenger. The participants had to make snap judgements as to whether or not a foul was being committed. What the participants did not know was that they actually viewed each of the 100+ images twice: once in its original orientation, and once flipped to change the direction of play (numbers and letters were removed so that this would not be apparent). The authors found that on average, their participants called about 3 more fouls on right-left moving pictures than left-right moving pictures. While this is a small difference, it was found to be statistically significant. Given that they viewed the exact same images once from each angle and were more likely to call fouls on those images when they were moving from right-left, this would support their original hypothesis that there is an inherent bias in favor of left-right movement, and that the threshold of judgement for calling a foul is lowered when the referee is watching events unfold from right-left.

What does this mean for the game? As anyone who has ever watched a soccer game will know, fouls are very important to the outcome of the game. They result in free kicks or penalty kicks which can often result in a goal, and the margin of winning scores is notoriously low. A bad call in a soccer game can much more easily influence the outcome of that game than in other sports, and if referees are naturally biased towards calling fouls during right-left motion, this can put one or the other team at an immediate disadvantage.

Soccer referees generally patrol the field using a diagonal system of control, meaning that they view one end of the pitch from left-right and the other end from right-left (there is an excellent diagram in the paper that illustrates this concept, which is free online since it is in PloS ONE). Since the teams switch ends of the field at halftime, the bias tends to equal itself out as long as the referee doesn’t switch diagonals, however there is currently no rule in place to stop the referee from doing so. FIFA may want to take this visual bias under consideration when advising their referees. However, recent news seems to indicate that after the events of this year’s World Cup, they are open to reexamining their stance on instant replays. FIFA president Sepp Blatter says, “It’s obvious that after the experiences so far at this World Cup it would be nonsense not to reopen the file. [...] Something has to be changed.”

Is it possible that the bias observed in this study was at play when referee Coulibaly made the call to disallow USA’s goal? Well… probably not, but it is possible. If you look at the screencap above, Coulibaly is circled in yellow and the general path of the ball is traced in red. From his vantage point, he would be viewing the play from right-to-left. Coulibaly is from Mali, where both the official language (French) and the lingua franca (Bambara) are read left-to-right, so it is reasonable to assume that he would have the same visual bias as English speakers. It is possible that his threshold for foul-calling was lowered because of his vantage point and inherent bias, but we’ll never really know. And, in this case, it doesn’t even matter since we went on to get our asses kicked by Ghana in the round of 16.


Alexander Kranjec, Matthew Lehet, Bianca Bromberger, Anjan Chatterjee (2010). A Sinister Bias for Calling Fouls in Soccer PLoS ONE, 5 (7) : doi:10.1371/journal.pone.0011667

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