Computer scientists and gesture experts at New York University and Berkeley think body language might play an important part in how we perceive the sincerity of politicians.

By analysing over half a million high-definition video frames, sounds, words and gestures from the three US presidential debates, they calculated which words from President Barack Obama and his challenger Mitt Romney had the most “gesture weight” behind them.

This “gesture weight” was calculated by the intensity of the body language that accompanied each word. The comprehensive computerised study of movements and gestures of the candidates found that certain words had weightier gestures behind them. Obama stressed “jobs”, “business” and “companies” more than Romney did, while Romney emphasised “government” more than any other word.

The scientists came up with a scale for body movement and labelled the most intense full-body gestures as posture-gesture mergers.

These occurred when the candidates were talking about something about which they were passionate: their personal beliefs or previous accomplishments.

The study noted that many of Romney's full-body gestures occurred when he was criticising the Obama administration rather than outlining his own agenda. Interactive video clips can be found at gesturecloud.org.

“When you listen to politicians speaking, your response is based not only on what they say, but how they speak,” says Prof Chris Bregler of NYU’s Courant institute of mathematical sciences. “How they move influences whether you believe they are standing behind what they are saying – or if you get the impression they are simply repeating a memorised list of terms.”