This could be pretty useful if you have young children. How To Tell When Someone Is Lying – Forbes. Don’t have time to read the whole article? Here are the high points.1. Look for deceptive behaviors and responses within the first five seconds of asking a question. 2. Someone telling the truth will say immediately and plainly that they did not commit the crime. 3. Liars often respond to questions with truthful statements that cast them in a favorable light. 4. Liars often repeat a question to stall for time, go into attack mode against the questioner or butter up the questioner with compliments. 5. Nonverbal cues to lying include hiding the mouth or eyes, throat clearing or swallowing, grooming gestures like adjusting shirt cuffs, shifting weight around and sweating.