说到测谎器的原理,其实是十分简单的。人们在不得已时,不得不说谎的时候,脸色都会变,额头冒汗,手也会紧紧地握着。这样,很容易被人看出在说谎。不过有时或惯说谎话的人,脸上则一点也不会露出慌张的神色;他只会冒些令人看不出来的冷汗,或脉搏加速跳动而已。 When it comes to polygraph principles, it’s actually very simple. People have to change their face when they have to make a lie, sweating their foreheads and holding their hands tightly. In this way, it is easy to be seen lying. However, sometimes people who used to lie, their faces did not show a look of panic; he would only take some people can not see the cold sweat, or pulse beat it.