Hi @christiakoursa, it's definitely a fascinating subject. I encourage you to do some research on your own (Google Scholar is a great resource) but here are my thoughts:
It is possible for a lie to convert itself into 'truth' and cause the brain to process it as truth meaning that the body wouldn't show any sign of deception, so I believe that a lie could be rehearsed enough that the brain recognizes it as truth. And I totally agree that they pick the best and most believable shots for the final edit.
Let us know what you find!