Thursday, August 19, 2010

The Sinister Side of Officiating

In western cultures, left has been described as sinister whereas right is more spiritual. These cultures read and write from left to right and tend to view movements in that direction more favorably. Hollywood and other artists have exploited this perceptual bias for years. The good guys often enter scenes from the left and move right. On the other hand, villains enter from the right and move left, a more disturbing direction. Researchers at the University of Pennsylvania wanted to see if there is a perceptual bias in how referees assess fouls. Do referees see leftward moving challenges as more “sinister” than rightward moving? The results suggest that the official’s vantage point may actually influence the call.

A group of experienced players were asked to view photos of scenes from professional league matches. The scenes always involved two players only, one player was clearly in possession of the ball while the other was making a strong challenge, and the direction of movement was clearly left-to-right or right-to left. Each picture was shown to the participant and he or she was asked to quickly make a judgment call (foul) or withhold judgment (play on). 134 pictures were used with half showing each direction of movement.

The study participants called approximately 5% more fouls when the offending player’s movement was right-to-left compared to the other direction - a statistically significant difference. Response times were similar for each direction of movement.

The results do indeed suggests that there may be a sinister bias in calling fouls. Left-to-right challenges are viewed more favorably and right-to-left less favorably.

The authors point out that this is not the first study to show a leftward bias in soccer. Italian subjects viewed goals scored from a left-to-right direction as more “beautiful”. On the other hand, Arabic subjects (who read from right-to-left) viewed rightward goals more positively. In the present study, subjects were all from the west.

How might this affect the course of a match? The researchers note that the diagonal movement pattern of referees during a match typically places then in a position to view offensive attacks unfold from right-to-left. This is direction shown in the left side of the figure. In this case, the defender is making a challenge from right and moving leftward. If the researchers are correct, this play is more likely to be called a foul than a challenge from the other direction. From a perceptual bias, the defenders actions are moving in a sinister direction.

The assistants (such as shown in the figure) should have the opposite vantage point - most challenges will come from the right. Unfortunately, for the defender, it is the referee that makes the call.

The diagonal movement of the referee could be a distinct advantage for the offensive players. Given that referees will more often than not view attacks as leftward movement, challenges made by defenders are more likely to be penalized. However, the potential bias should carry over the both ends of the pitch and remain constant for both periods of the match. As the authors of the study point out, soccer may have stumbled on a good system of consistency. The only exception being when play forces the referee to change his or her vantage point and view attacks as moving the other direction.

There are a few drawbacks to the study and several questions remain. This study asked participants to view images and render a decision. Video showing the run of play was not used. The researchers also did not examine actual game footage to determine a referee’s vantage point and mark whether or not more fouls were called during leftward or rightward challenges. Also, they did not include subjects from cultures where right-to-left movements are considered more acceptable. Despite this, the findings do provide some insight into how referees make decisions. Maybe some players and coaches are correct – many referees are sinister.


Kranjec A, Lehet M, Bromberger B, Chatterjee A (2010) A sinister bias for calling fouls in soccer. PLoS ONE, 5:e11667.