What Body Language Experts Tell Us About the Third Republican Debate

— -- Presidential debates may be mainly about what the candidates say – but it can be just as much about what they don’t say.

Body language is a critical part of how candidates are perceived by voters, and many candidates invest hours honing how they come across to millions watching on television.

So ABC News went to three body language experts for their opinions on how each candidate was portraying himself or herself during the debate.

Joe Navarro, who wrote the book “What Every Body is Saying,” is a former FBI agent who used non-verbal analysis to identify spies and gain counterintelligence. Janine Driver is a New York Times bestselling author who now leads a body language training at the Body Language Institute in Washington. And John Neffinger is a communications strategist who teaches at Georgetown University and Columbia Business School, and also coaches politicians to communicate more effectively.

Here’s what they told us:

ABC News: Donald Trump’s frontrunner status in the race for the GOP nomination was beginning to slip as the debate approached. So what can we learn about the brash real estate mogul – even with the volume off?

Joe Navarro, former FBI agent: Notice Trump’s emphasis and use of a precision grip as he says that he doesn't forgive people who let him down. We usually only use that precision grip -- index finger to thumb -- when we have certainty about one topic or sentiment. Also see that Trump is the only one that touches the microphone, which is a territorial display. It says that everything in front of me is mine -- not just the podium, but what’s on the podium.

Janine Driver, body language instructor: Trump once again "keeps it real." From acting like a little kid mocking Kasich, to "like-what-I'm-saying-right-now" a-okay steeples, to more aggressive palm-down gestures, pointing and chopping, all his moves are all integrated, which means Trump is being authentic. He’s saying we don't need to second-guess or question if his opinions are genuine.

John Neffinger, communications coach: Trump brought his signature style, forceful but under control. But he's not having as much fun as he was in the first debate, the novelty has worn off, and the polls may have rattled him. His gestures are smooth when he's confident and jerky when he's agitated, and tonight they were more jerky. He's also overusing a particularly funny clown face where he pinches the sides of his mouth. Again, tension.

ABC News: Supporters of Ben Carson, who is now leading Trump in Iowa, say they like his thoughtful, deliberate approach. What other signals did Carson send to voters about himself with his body language during tonight’s debate?

Navarro: We tend to gravitate to those who appear in control, measured, deliberate, even-tempered. Dr. Carson is the only speaker to steeple his fingers -- touching fingertip to fingertip. It is one of the few signs that we humans have of confidence. Is there a downside to this demeanor? Yes. Someone who takes too long to answer, is too deliberative or seems incapable of quickly answering will in a debate format not come across well.