Seemingly Uninvolved Players' Impact on Assistant Referees' Offside Decisions

Most studies on offside decision making in soccer have not addressed rather simplistic situational probabilities like the number of players involved in an offside situation. In three studies (one observational and two experimental), the authors tried to assess whether the number of players close to the offside situation can predict the quality of offside decision making. In all three studies, they found that the presence of additional players negatively affected the percentage of correct decisions. The exact relationship between the number of players and the decrease in decision-making performance differed between the studies, though. Importantly, there was a negative influence of the number of players on decision-making quality in Studies 2 and 3, even though the authors tried to add players clearly farther away from the offside line than the relevant pair of players. This points to a crowding effect as a potential explanation for why decision-making quality decreases with an increasing number of players.