Among all the athletes, medals, and records, that we enthusiastically cheer for during the Olympic Games, we might forget some very important contributors to this event: The referees. They deserve tons of enthusiasm, because we ask them to do something even more superhuman than running the 100 meters in 9.6 seconds: They are supposed to make absolutely unbiased and impartial decisions.
It is common consensus in neurobiology, psychology, and nowadays even economics that humans are quite bad in this discipline. Most our decisions are heavily influenced by irrational and impartial factors. Long lists of known cognitive biases have been compiled and it would be a big surprise if referees could elude those biases.
Since referees’ decisions often have a big impact on the outcome of a sports event, studies with the aim of finding common referee biases have been conducted. M. Sutter and M. G. Kocher, for example, could confirm that German football referees significantly favor the home team. Obviously, it is difficult for an individual referee to make decisions, which a huge crowd disapproves of. L. C. Findlay and D. M. Ste-Marie investigated marks in figure skating, where a group of judges gives a ruling on the athletes’ performance. They could show a so-called reputation bias, i.e., the judges have the tendency to give better marks to athletes that they know in advance.
These are only two among many secured referee biases. To avoid them the setup plays an important role. Figure skaters, for instance, are evaluated by a group of judges with the hope that the biases level out. In some sports like field hockey and fencing instant video replay has been introduced as an aid in controversial decisions.
Investigations on referee biases do not only help to improve judging in sports events. They may also be important to economy, to be more exact to principal-agent theory, which is nowadays applied to a lot economic problems ranging from energy consumption to employment contracts. This theory focuses on the actions of two parties, the agent (e. g. the management of a company) and the principals (e. g. the shareholders of this company). The agent has more information than the principals and tries to convince the principals to act on his (or her) behalf. In this setup it is crucial to know how these two parties decide, which biases they are subject to and to which extent they are influenced by irrational factors. For example, the referee’s (=agent’s) home bias might shed light on favoritism exerted by managers if they are confronted with a disapproving crowd of shareholders.
 M. Sutter and M. G. Kocher, “Favoritism of agents – The case of referees’ home bias”, Journal of Economic Psychology, 25 (2004), 461-469
 L. C. Findlay and D. M. Ste-Marie, “A reputation bias in figure skating judging”, Journal of Sports Exercise & Psychology, 26 (2004), 154-166
— Leonie Mueck