As George Bush and John Kerry faced each other in a televised debate ahead of the presidential elections, they knew how important a strong performance was.
The president's frustration was apparent, says Wood
What they might not have realised is that their body language would also give an intriguing insight into both men.
BBC News Online spoke to Patti Wood, an Atlanta-based body language expert, who explained what both men's unspoken actions might mean.
The president looked most at ease during the first 30 minutes of the debate, according to Ms Wood.
"He was warmer, more confident, he spoke from his heart, smiled and looked into the camera," she says.
But in the remaining hour, Mr Bush sounded increasingly angry and repeated many of his answers, she adds.
The constant use of statements - such as "the war was hard work" - showed that he was speaking from a script, she says.
"When you hear the same words with more frustrated body language, the message sounds like a lie."
Ms Wood said the president's frustration was especially visible when Mr Kerry was speaking.
"In reaction shots Bush was arrogant, smirked and shook his head and looked disgusted in a childish way.
"This indicates immaturity - which is not presidential. He should have been more in control," Ms Wood said.
Mr Kerry, by contrast, would look at Mr Bush and appeared more respectful.
However at his best Mr Bush can still project a more comfortable image than his challenger, Ms Wood notes.
"If Kerry is to win, he has to look at the public through the camera when he speaks," she adds.
She said Kerry looked more in control
Mr Kerry needs to take a leaf from the president's book, lean forward and speak warmly, Ms Wood says.
Instead of using the classic debating technique of looking at his opponent, he should look at the public through the camera, she suggests.
Ms Wood made clear body language would not influence committed supporters of either candidate.
But, she went on, "it is going to make a difference for anybody who has not made up their minds who they are going to vote for."