Your mother always told you not to lie: it’s easier to tell the truth. She wasn’t pulling your leg: Duran, Dale, and McNamara (2010) recently showed that lying can physically pull you in two directions. And they did it with a Wii.

Robert DeNiro knows you're lying. But instead of an old-fashioned lie-detector, he can just use a Wii next time.
The Nintendo Wii is a video game console that uses motion sensing as input. You aim the Wii-mote at the game console, and movement of the controller translates into on-screen movement. This motion sensing controller makes games more fun by letting you use real-life movements control your characters’ movements onscreen.

Participants answered questions by moving the hand cursor from its starting point to one of the buttons on top. (Note: this is a mock-up, not the actual screen used).
Duran and colleagues showed participants simple yes or no questions, like “Have you ever been to Asia?” or “Have you ever eaten frog legs?” Sometimes people were asked to lie when they responded. They answered by moving the cursor from its starting point in the bottom center of the screen, to “yes” or “no” buttons in the top left or right corner.
When people told the truth, they pointed the Wii-mote more or less straight to the answer. But when they lied, the Wii-mote tended to arc toward the true answer before veering off to the false one. So telling the truth is straightforward. Lying, however, involves conflicting mental urges, which physically pull you in two directions. First, automatically, you’re drawn toward the truth (Hey, your mother was right, you are a nice boy!). Then, with effort, back toward the lie (sorry Mom!).
Lying in the real world doesn’t quite work this way (after all, how often do we answer questions by pointing?) But looking at physical movements here gives us insights about lying that would be hard to get with other methods. Imagine if, instead, you actually asked people to describe their thoughts during the whole lie. They probably wouldn’t say, “I’m telling the… LIE! I was honest at first but I changed my mind, BOO-YAH!” (well, it might work with Robin Williams).
So girls, if you really want to know whether you look fat in that dress, ask your boyfriend via Wii-mote. But guys, no matter what, never answer your girlfriend’s questions via Wii-mote.
Sources:
Duran, N.D., Dale, R., & McNamara, D.S. (2010). The action dynamics of overcoming the truth. Psychonomic Bulletin & Review, 17 (4), 486-91 PMID: 20702866

