* Home team status not always an advantage
* Studies show roaring crowds influence officials
* Spectators can spur athletes, but can also turn on them
By Kate Kelland
LONDON, July 27 Home team advantage has long been recognised as valuable in sport, but scientists suggest the roar of the crowd at the London Olympics may be worth a lot more to some athletes in the British team than others.
Having the nation behind you can bring a much-needed boost in the final miles of a gruelling marathon or 10-km swim. Yet the added pressure of expectation and fear of failure so close to home can have its downsides too.
And analysis shows it may be the crowd's effect on officials, judges and referees, rather than on runners, jumpers and swimmers, that makes the biggest difference.
"Home advantage is really not always an advantage. Sometimes it's a disadvantage. And often it's about what the athletes and coaches expect, and how they embrace it," said Antoinette Minniti, a lecturer in sport and exercise psychology at Nottingham Trent University.
She identified various factors that can work in the home team athletes' favour: familiar surroundings, the backing of the crowd, less travel and being acclimatised to the weather, food, air and culture.
But there are also home nation factors that can have a negative impact on performance, including increased pressure and expectation and worries about letting people down.
"Arousal and home advantage are very interconnected," Minniti said. "But while anxiety is a negative thing, arousal can be either facilitative or debilitative. It's very much about how the person perceives it.
"The athletes who interpret the Olympics home game as a positive thing will do better."
WHO'S LISTENING TO THE CROWD?
In an analysis of home advantage published in the Journal of Sport Science last year, British sports scientists found host nation advantage does tend to show up in the medals tables of Olympic Games.
Home teams win around three times more medals at their nation's Games than when they are away, the researchers found.
The analysis also found the greatest influence comes not from familiarity with the surroundings or lack of jet lag, but from the roar of the crowd.
And the cheering doesn't just affect the athletes.
In sports where referees or judges make decisions, give grades or allocate points - such as football, gymnastics or boxing - the researchers found that home advantage is likely to be particularly evident.
In sports where there is less subjectivity, such as athletics, athletes gain less from home advantage since there are no officials to be influenced.
"Our findings suggest that crowd noise has a greater influence upon officials' decisions than players' performances," wrote the researchers, led by professor Alan Nevill from Wolverhampton University. "Events with greater officiating input enjoyed significantly greater home advantage."
In another review of scientific analyses of the phenomenon published in the journal Sports Medicine, Nevill said numerous studies support the suggestion that crowds can influence officials to subconsciously favour the home team.
"Clearly, it only takes 2 or 3 crucial decisions to go against the away team or in favour of the home team to give the side playing at home the 'edge'," he said.
Richard Stevens, a senior lecturer in psychology at Keele University, pointed out that crowds can also turn.
"It can go either way," he told Reuters. "It can help if the crowd is supportive but if it becomes very critical it can go the other way." (Additional reporting by Belinda Goldsmith; Editing by Sonya Hepinstall)