How we change what others think, feel, believe and do
The Open-Closed Lie Detection Method
This is a method for detecting lies by first asking open questions, then homing in on specific detail to check for accuracy and consistency.
Start by asking them an open question that gets them talking. Use phrases such as:
Encourage them to keep talking with nods, smiles and other non-verbal prompts. Listen carefully to the detail of what they are saying.
Pick specific aspects from there answer where you would normally expect them to know further detail and ask closed questions about these. Ask cross-checking questions that helps you check the truth of previous statements. A way of doing this is to appear confused, which gives you reason for asking questions again or differently.
Watch for hesitation, inconsistencies, fogging, anger and other methods the person may use in their answers that could indicate lying. If you think they are lying, do not use just one piece of evidence. Look for more. Give them every opportunity to be inconsistent or otherwise dig themselves into a deeper hole.
Q: What went on here last night?
People generally like to talk and be heard and so when you give them the opportunity and suitable encouragement they will talk at length. People who are not lying are not troubled by this. Liars may worry about being found out and say very little, which is itself an indicator (though beware of confusing these with introverted honest people). Realizing this, they may well also try to appear normal and spin a story, talking at length about the situation. Another indicator here of lying is that they may go on rather longer than they might otherwise, either trying to cover all the areas you might question or just trying to filibuster, taking up all available time.
Even if they answer the open questions well, they have given you a lot of information into which you can dig further, asking short-answer closed questions puts a liar on the spot. They may have rehearsed the overall story, but will not have ready answers to detail questions. As a result they may hesitate as they think about what to say. The timing of this is important as honest people will have easily accessible memories. Honest people may also not remember some things, and will happily say this. Liars may try to use this, but will be inconsistent in the proportion of forgotten items, for example pretending to forget most details. They may also use anger to try and get away from this discomfort.
Using this approach, Rothermich and Pell (2015) detected lies in a controlled experiment 70 per cent of the time, which can be up to 20 times more effective than other techniques such as looking for physical signs of lying.
Use this method to detect lies. If you can remain natural in your questioning, it will keep the person at ease and avoid them feeling that this is an interrogation (which is helpful for both checking on liars and honest people).
Remember that even when you think you have detected a liar (or honest person) you may be mistaken. All this method does is give you a better chance of detecting lies.
Rothermich, K. and Pell, M.D. (2015). Introducing RISC: A New Video Inventory for Testing Social Perception. PLoS ONE, 10, 7, 1-24.