People are different – so first establish the base line of the person
Establishing a base line. [The natural way a person reacts]
Ask positive non-intrusive questions or make positive statements to determine the persons base line
Take note of any irregularities for example, the person may be touching their nose frequently.
This could be a cause of hay fever or another reason and not necessary mean the person is hiding something.
Another example, is that the person may have damage to their hands and could be by nature comforting their hands.
The point is, is that the person may be doing something which could be regarded as an indicator but it may not be so due to other reasons.
Furthermore, and most importantly, make sure that they are in the conversation when you asking them the questions, as they could have a thought pass through their mind and may react to that thought and not your question.
The hands show how someone feels and also how the person thinks