Referees are often accused of being blind. Turns out they hear just fine, however.
A roaring crowd can subconsciously influence some referees into giving the home team an added advantage.
Ryan Boyko, a research assistant in the Department of Psychology in the Faculty of Arts and Sciences at Harvard University, led a study of more than 5,000 soccer matches in the English Premier League between 1992 and 2006, involving 50 different referees.
"Individual referees and the size of the crowd present are variables that affect the home field advantage," Boyko said.
Home teams scored 1.5 home goals on average, and 1.1 while away. For every additional 10,000 people in the crowd, the advantage for the home team increased by about 0.1 goals.
More significant, away teams received more penalties, suggesting referees make calls in favor of the home team, possibly as a result of the influence of the crowd, Boyko and colleagues speculate. A separate study last year reached the same conclusion.
But Boyko's team found that some referees are more susceptible to these influences than others. More experienced referees are less biased by the impact of a large audience, which suggests that they may develop a resistance to effects of the crowd, the researchers conclude.
The study, announced today, will be detailed in the Journal of Sports Sciences.