how can you tell if someone is lying ?

Question: how can you tell if someone is lying ?
- Keywords:
  body language,
  detect,
  eye contact,
  lie,
  lying
Asked by rachelbowesxx to Amy, Drew, Julia, Kimberley, Sara on 20 Jun 2011.
- Julia Griffen answered on 20 Jun 2011:
  
  I wish I knew!!! hehe…
- Amy MacQueen answered on 20 Jun 2011:
  
  Well…you can’t always definitively tell but (as general rules) if someone won’t look at you when responding, is fidgety, takes a while to give you an answer, changes their story on a re-telling and is saying something that you know is not true they are usually lying! 🙂 Apparently rather than looking up to the right when telling a story (for “remembering”) a person’s eyes will flick up to the left…this is the more imaginative side of the brain and so they are more likely to be making something up!! 🙂
- Drew Rae answered on 20 Jun 2011:
  
  They’ve done experiments that say that supposed experts like police-officers and “body language experts” are actually worse than flipping a coin at telling if someone is lying. I guess the lesson is don’t use their voice or their mannerisms, since those can be communicating “I’m stressed” which looks like “I’m lying”. Instead, go look for evidence to check the facts and compare it to what they say.

Question: how can you tell if someone is lying ?