Another NFL season is here, and though there’s no scientific way to win the office pool, keep an eye on the home field. NFL teams win at home about 60 percent of the time, and British studies of soccer matches do much to explain why.

First, try as they might to ignore the fans, referees can’t. In one study, soccer refs viewed videotaped plays with and without crowd noise. When home fans were screaming in their ears, even the most experienced officials favored home players.

In a second study, psychologists Sandy Wolfson and Nick Neave of the University of Northumbria took saliva from professional soccer teams one hour before a home game, an away game, and a practice. Testosterone levels were found to be around 50 percent higher before home games than before away games.

The scientists say these rises in testosterone correspond to what home teams perceive as “territorial threats.” But they caution that testosterone is only beneficial up to a point. Extremely high levels of the hormone may be associated with impulsive and counterproductive aggression, leading to poor decisions.