I'm curious, in face to face or verbal contact with people, are there any cues you find helpful in telling that people are lying, other than spotting inconsistencies in what they are saying? I tend to pick up on tone mostly. I've been meaning to try and record myself lying to see if I can hear it in my own voice, but I've never gotten around to it. I know there are other things, like eyes and so forth, but I've never found that as useful.
Looking away (towards the door if there is one), closed body language (arms crossed, angled posture), and when all else fails, talking around and fudging the basic facts. Some more subtle ones are elevated heart rate and perspiration if they think you're onto them, and the dilated blood vessels means more exaggerated tics like rubbing/scratching the face. Granted it's easy to talk about and hard to see unless the person is having a full-on fight or flight response, but if you look closely while you suspect somebody is lying, try to get them to repeat the supposed lie. Each time they say it they should get more stressed. *Just lying about silly stuff won't get you a reaction; it's the fear of getting caught which makes people give off signs. ^^tips learned for doing police investigations. Of course it's easy for the cops because they let people lie and get other kinds of evidence, for the most part. Lies can be as useful as the truth in some cases.
I've had a history of compulsive lying about some things (not my info, I promise, that's all correct ) so there are a lot of small little body language things that you pick up. Argentwing covers the major things to look for when people are lying, but the best way to know if someone is lying is just seeing if they are acting any differently to normal, even in small ways.
I have picked it over time. I guess it's because I feel like that lying and deception has caused me some anguish in my life, so I've been more cautious towards it than others. I've been to events, and after two minutes of chatting with the individual, I can pretty much tell if the person doesn't like me or is genuinely being nice to me. You know what I mean? Where you don't like someone for whatever reason but you still have to be nice and put a nice smile on your face? Yeah, that has happened to me quite a bit. Also, I have an extremely good eidetic (photographic) memory, so whatever you tell me now, I can use that against you when you try to say something else that contradicts what you told me earlier. For example, there was this one individual in a student organization on campus that I intended. It was the Latin American Student Association. I went there because I was the Spanish club president and I wanted to collaborate with their organization, and also because I was generally interested in learning more about Hispanic culture, etc. But that's not the point. There was this one individual who refused to speak back to me in Spanish whenever I would speak to him. Why? He told me that he understood "bits and pieces of it" since he was born here in Georgia, yet his Colombian parents never taught him Spanish. Okay, that I can understand. That was late last year. I check my Facebook a couple of months ago, in May, and it has the same guy touting that he got a full scholarship to some university. Why? Because he had full fluency in Spanish. Wait what ? So, as you can see...I've gotten used to people lying and I knew that this person was lying from the start and just using it as an excuse to not want to deal with me, for whatever reason. I could pick up that the guy would act super duper smiley towards me, yet whenever I tried to talk to him on Facebook, he never answered my questions directly, flakier than the most intense dandruff imaginable, and would act like a complete douchebag towards, getting very defensive and avoiding the question.
