Does the crowd affect the result?

Two sets down against Richard Gasquet, Andy Murray seemed dead and buried. But backed by a vociferous crowd he turned it around and won the match. So how much influence can the audience at a sporting occasion have?

At times during his five-set thriller Andy Murray looked as if he was conducting the crowd on Wimbledon's Centre Court, and he paid great tribute to their influence afterwards. But there is disagreement in the world of sports psychology over just how much the crowd can achieve.

MAKES HOME TEAM PLAY BETTER?

It doesn't need a survey to tell you that the vast majority of sport fans believe in the power of home advantage, and believe that the crowd has the key role in that advantage. "There's plenty of research out there which says crowds have an effect on athlete performance," says Matt Jevon, a sports psychologist who works with stars in golf, motorsport, rugby and tennis. In footballing terms it's often referred to as the "12th Man", the power of the crowd to amplify the abilities of the home team and weaken the away team. Dutch club Feyenoord went as far as dedicating the number 12 shirt to the fans. And certain football stadiums are notorious to opposition fans because of the consistency of the noise generated by the crowd and the perceived difficulty in going there. Valencia's precipitous Mestalla stadium, the red wall of Liverpool's Kop, Celtic's Parkhead on a European night and the notorious cauldron of Galatasaray's Ali Sami Yen are all well-known internationally.

But there are plenty who say home advantage is down to a more complex raft of factors than just the noise. "It is not really the crowd that has the biggest effect, it is a shot of testosterone when you are playing at home," says sports psychologist Sandy Wolfson. The testosterone boost starts happening even before the crowd arrive, and may relate to a sense of primitive territoriality. Some animals perform better in conflicts with rivals when defending their home territory than attacking foreign territory. Then there's also travel fatigue, disorientation, and unfamiliarity with an idiosyncratic pitch to be considered.

MAKES REFEREE PERFORM BADLY?

Another factor that may explain home advantage is the crowd's effect not on the players, but on the match officials. "In football, it's the referees that make the difference. If there is a harsh challenge, the crowd roars and the referee reacts," says Prof Ellis Cashmore, author of Sport and Exercise Psychology. It is common to see a referee miss a bad tackle on a player from team A, realise he has made a mistake, have booing directed at him, and then be lenient to the players of team A for a few minutes afterwards.

A Harvard University study last year of 5,000 English Premier League matches suggested away teams gave away more penalties. The crowd effect was particularly pronounced on inexperienced referees. In boxing it has occasionally been suggested that judges have a subconscious home bias, for example unwittingly favouring the American fighter in a Las Vegas bout over his foreign opponent. In tennis of course, the decisions are too clear cut for subconscious bias to be possible. And yet there was a key decision that went in favour of Murray in his match with Gasquet. The Frenchman was desperate to go off for bad light and resume play in the morning. The crowd would have reacted angrily if this had happened. And in the event, both the umpire and tournament referee seemed happy that the light was adequate for play to continue.

MAKES OPPOSITION PLAY BADLY?

In the Murray/Gasquet match, the Frenchman was visibly annoyed by the amount of crowd noise immediately before points and between serves. Making noise between the first and second serve is considered particularly unacceptable in tennis, but occurred numerous times during the fifth set. Gasquet has a reputation as a psychologically frail player, and it's not beyond the realms of possibility that this was putting him off. "During the first couple of sets Gasquet had got the crowd pretty quiet," says Jevon. "They were sitting there thinking 'another British loss'. As soon as there was a pick-up in the crowd noise and involvement, Gasquet wasn't mentally tough enough."

Coping with an unexpected Murray resurgence was difficult, but allied to a sudden jump in pro-Murray crowd volume it was very problematic. "You can't be human and not notice these things," says Jevon. "The more you try and block something out the more you have to deal with it."

In golf, another game where the competitors are accustomed to quiet, it has been suggested that when a player is barracked, as Colin Montgomery often has been in the US, his performance could be affected. In Italy's clash with Spain in Euro 2008, the Italian forward Antonio Di Natale was roundly booed by the audience as while "injured" and off the pitch, he rolled back onto it in order to get the referee to stop the game and thereby stop a Spanish attack. When it came to the penalty shoot-out his poor effort - amid whistles and jeers - was easily saved.

DISTRACT THE SUPPORTED PLAYER?

Of course support can be too much. There has been at least one survey suggesting that it is an advantage to take a penalty shoot-out in front of the opposing fans, the theory being that the pressure becomes too great in front of your own fans. And there are plenty who thought Tim Henman struggled to cope with the pressure lumped on him by the crowds. "There is some lab evidence that the support of crowds can have a negative effect," says Prof Wolfson. "The performers always think the supporter or the audience had a positive influence but sometimes it didn't."

And if you want to be gee'd up when you're down, and you get the crowd going, as soon as you've turned things round, you still want to be able to screen out excess noise so you can concentrate. "You have got to be confident as a team that you can cope with the outcome of you stimulating that kind of support," says Jevon. In Murray's battle with Gasquet, the commentators noticed he was focusing on particular individuals in the crowd to motivate himself. This controlled use of crowd energy could be the answer.