Olympics-The roar of the crowd: A home advantage for team GB?

* Home team status not always an advantage

* Studies show roaring crowds influence officials

* Spectators can spur athletes, but can also turn on them

LONDON, July 27 (Reuters) - 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)