Have you ever considered that your judgment was biased simply because your brain is wired in such a way as to negatively perceive events unfolding from right-to-left? Well, the scientists at the Neurology Department and the Center for Cognitive Neuroscience of the University of Pennsylvania conducted a scientific study to test whether movement from right-to-left (leftward movement) predisposed soccer referees to call a foul. According to the authors of the study, populations that read from left-to-right demonstrate a well-documented perceptual-motor bias which creates discomfort with the leftward motion. This discomfort leads these populations to view or perceive events moving from right-to-left (opposite to the direction in which they read/write) in a negative way. So, for example, readers of left-to-right languages were found to “rate goals scored from left-to-right [rightward motion] as more beautiful than goals scored in the opposite direction.” The experiment’s hypothesis proposed that American referees (or, simply put, those from western-world nations whose languages are read from left-to-right) would be more predisposed “to call a foul when the direction of play moves leftward.”

The experiment tested responses of twelve (12) participants who each were shown 134 pairs of photographs (the original and flipped versions). The photographs were shown to the participants in two intervals and randomly. The experiment was designed in such a way that when one version of the photograph was shown in the first half of the experiment, its counterpart was shown in the second half of the experiment.

The results were astonishing.  According to the authors, participants called approximately 3 more fouls when pictures were viewed in their left-moving (66.5 fouls) compared to their right-moving (63.3 fouls) orientation. The authors proclaimed that “this finding means that an individual participant was more likely to call a foul when seeing a picture in its leftward compared to rightward orientation, even though the two [pictures] were otherwise identical.

So how does this alleged perceptual-motor bias to call more fouls from the leftward direction affect soccer referees and the game? Consider that the laws of the game require referees to use a diagonal system to patrol the field of play and that the left diagonal system is primarily employed in today’s game of soccer. As the authors rightly pointed out, in the left diagonal system, the referee will generally observe a play from right-to-left in the attacking third of the field. The results of this experiment imply that the referees using the left diagonal system favor the offense for both teams because they will observe most of the attacks from right-to-left; therefore, they will be expected to be more predisposed to call fouls [against defending teams] during attacking plays at both ends.

You might think that this perceptual-motor bias may unfairly favor one team over the other. But that, actually, is not the case, because “when referees run diagonals consistently during both halves, left-right directional regularities are the same for both teams.” In other words, the offenses of both teams are equally benefitting from the referee’s alleged perceptual-motor bias to call fouls against the defending team at both ends of the field. Thus, the authors point out that “soccer may have [accidentally] stumbled onto a good system” of refereeing the game.

Do you think that your judgment is impaired because of this alleged leftward negative bias? What should – or could – you do to counteract it? Let us know what you think.

Citation: Kranjec A, Lehet M, Bromberg B, Chatterjee A, A Sinister Bias for Calling Fouls in Soccer, PLoS ONE (2010).