Hmm...can't say I've ever felt like a person looked totally different, but I don't tend to notice people's features anyway...
You know, people say they can read faces and the faces betray a persons real emotions, which is actually very much true, but it only lasts sometimes mere split seconds (meaning you need training or a camera with a very high FPS to see it). When a person being interviewed realises the police know more than before, he'll feel fear, and for roughly 1/25th of a second it'll appear on his face before he hides it. If the interviewer blinks, he'd miss it.
Our hands, our body language, betray more transparently our true feelings than our face does. For example, people often use their hands to help them explain something, often without realising they are doing it. If a friend of yours was explaining that he found a wallet, and you noticed that he was miming out the actions of picking it up with his hands, and of riffling through it, and when he said "I got rid of it", he half-mimed putting it into his coat pocket and not throwing it away (as he implied), it would make me suspect he actually pocketed the wallet, and I'd try to bring up in a non-confronting way whether or not he did pocket it.
Lies are even more fascinating, because of the misconceptions. I used to do a trick which went as followed:
I'd ask a person to think of a house I wouldn't know, it could be their house or anyone else's, as long as I wouldn't know it. I'd then tell them I was going to ask them three questions about the house:
1) The Number of the House
2) The colour of the front door of the House
3) The colour of the curtains in one of the rooms in the house
And they had to lie about one of these.
Now, for each question I'd observe the person's body language, their face, their hands etc, and afterwards I'd try to guess which one they were lying about. Now, if I was just guessing I'd probably hit the right answer about 1/3rd of the time, I've never been wrong. Of course, once I do this trick everyone there knows what I'm looking for and I can't do it with any of them ever again, so it isn't something I do a lot.
I've actually find most of the time the eyes give them away, because one of the greatest misconceptions about a lie is that you break eye-contact when telling one. !@#$%. People break eye-contact all the time whilst talking. This error is so ingrained in people that when lying, they often unnaturally maintain eye-contact.
Other times it's a slight nod of the head (or the lack of a nod), or some other subtle sign that gives them away. This trick is also great because it makes people afraid of lying to you
Anyway, yeah, went on a bit of a ramble there. I hope it's legible.
