this story teach you how to decern a liar. Dr. Lightman founded a company. Their business was to help some organization or agency like police , FBI to find weather some one tell a lie. The expression on your face or your body language would betray youself when you tell a lie. It would teach you some  skill to find the secret in one's heart. I had seen several episodes of this play. And I find a question, if all of lies were discovered you would find you were not happy and all of firends left you. The Chinese word is correct: Where ignorance is bliss, it's folly to be wise. 难得糊涂。