Everyone is curious to know about the elements of a good interview performance. People told me about the importance of body language and the way we present ourselves before the interviewer. So I studied in books about the different types of gestures and their significance. The collar pull gesture grabbed my attention. Research has proved that telling a lie induces a tingling sensation in the fragile neck and facial tissues and a rub or scratch was necessary to appease the feeling. This is exactly why some people pull their shirt's collar when they utter a lie and ponder in suspicion that they might be exposed. So whenever you expect a honest reply from a person watch out for his shirt collar. Exceptionally a person tends to pull his collar away from his neck when he gets enveloped by anger or frustration to let some air inside. Normally the interviewee should avoid using this gesture during his/her interview process. From the interviewer's perspective he can nail the culprit by simply asking "Would you repeat that, please?" or "Could you clarify that point, please?". Remember that there might be other genuine reasons for a person's gesture but the statements are based on a maximum likelihood estimation. Please don't lie. All the best!