How can you spot a liar? After conducting experiments with college students, researchers suggest you look at body movements. Their study published in Royal Society Open Science explains: Nearly 50 male students (females were excluded to "avoid the impact that sex may have on coordination") were paired with someone posing as a participant. Sophie van der Zee at Erasmus University Rotterdam in the Netherlands asked them to solve a wooden puzzle in 5 minutes and told them previous participants did so with ease, reports New Scientist. She left the room and "accidentally" left the puzzle's solution behind, reports Phys.org. The faux participant "discovered" it and urged the participant to use it to cheat. When van der Zee returned to the room, she saw the solution and confirmed cheating occurred. She then set up the lie.
Van der Zee asked them not to admit to seeing the solution in the subsequent interview because she had newly started her PhD and was worried about her supervisor learning of her error. That interview was between the student participant and another male student, and if the puzzle-doer did as van der Zee asked, he lied about how he solved it. Here's the key: Both students' head, chest, and wrist movements were tracked using a wireless accelerometer. The researchers found that when the participant answered truthfully, his body movements didn't align with those of the student asking questions. But when he lied, their movements tended to mimic each other—in a way that wasn't visible to the naked eye. Subsequent experiments found that the mimicking got more precise as the lies got more difficult or complex. Van der Zee's theory: that you need to concentrate to lie, so liars might subconsciously start to imitate movements because doing so takes less thought. (Read more discoveries stories.)