The Real Scoop on Deception Detection

I never thought I’d ever admit to this, but I enjoy watching America’s Got Talent. I love the dancers, acrobats, singers, magicians and comedians, but my favourite acts are the mentalists. I am always in awe of how they’re able to trick us into believing that they truly have magical powers. (They don’t, you know. Seriously.) 

They’re just extremely gifted at knowing the odds about potential responses to their questions or, conversely, at persuading another person to respond in a certain way. They are successful in an environment completely controlled by them where they are able to manipulate the subject and audience. In this way, they are able to make it look like they read minds. 

Now, if you still believe this is more than mere entertainment, there isn’t much point in reading any further as you wouldn’t believe in the mantra, “Assume nothing, Believe nobody, and Check everything”. What I’m hinting at is you probably would make important decisions on hunches alone and wouldn’t care about the difference between science and pseudo­science.

Even if you do believe that mentalists, when placed in a real world situation without all the gimmicks, could read minds with higher accuracy than chance, I wouldn’t be overly concerned. You see, the outcome would rarely have a serious consequence and the ruse wouldn’t usually cross ethical boundaries. It is good, old-fashioned entertainment and it leaves us awestruck and happy. I mean, it’s not as if they are ruining lives.

Now, compare the mentalist with, for example, a surgeon who chooses to use a technique that, according to scientific research, had a success rate of slightly higher than chance. Let’s put it at 54%. Would you be as forgiving with this surgeon as you were with the mentalist? 

Would you readily accept her professional, medical and ethical judgment should almost five out of every ten patients suffer a consequence worse than had the procedure not been performed? Would you sit back and do nothing if you found out you and many others had been hurt by this doctor even though she had been told about all the scientific studies? Would you easily accept her incessant bantering about having anecdotal evidence to support her technique? Would you walk away content if she had told you about all the unscientific field studies she had done that supported her beliefs about the efficacy of her work? Probably not.

As a police or private investigator we, like a doctor, owe it to ourselves, the public, and our profession to use methods that are scientifically supported, particular when the consequences could be hurtful to someone. We must diligently keep up to date on research such as the detection of deception, and use it to guide us in our quest for truth. To ignore the voluminous studies would make us as unethical as the surgeon who continues to hurt people despite scientific evidence predicting a negative outcome.

Scholars have repeatedly shown, with peer-reviewed research, that there is no Pinocchio’s-nose effect, meaning that there isn’t any physical behaviour that is a conclusive indicative of deception. In fact, studies have revealed that humans have about a 54% accuracy rate at detecting deception, regardless of the training they had received. 54% folks – think about it. 

That’s just a bit better than flipping a coin or, what’s the word I’m thinking of?... oh yeah, GUESSING. 

This means people are spending millions of dollars each year on courses that teach them how to guess. It also means that trained investigators are making important decisions on whether to believe victims, witnesses and suspects and they are, I say again, simply guessing. The lazy me wishes I’d done this my entire career as I wouldn’t have had to spend so much of my precious time investigating. 

So, lets move on and look at some excuses for not following the science.

“I look for clusters of deceptive behaviour”

Folks, if you bought ten cars that were missing an engine would any of the cars work better than if you had just bought one that was missing an engine? Of course not. Many useless things would not make the situation better for you. 

The idea that one behavioural trait would not always indicate deception yet many would, is frankly absurd. 

“I only use it as a tool”

I’ve never been able to fully grasp the logic here. If you use a tool that’s defective, the job won’t get done properly, will it? 

Would you be happy with our friendly surgeon if she decided to use a defective tool to perform brain surgery on you? 

As you’ll soon see, the bias created by the use of faulty deception-detection tools can be as damaging to an investigation as a dull, bacteria-infested scalpel can be to a patient. 

Confirmation Bias

You may be asking what the big deal is. I mean, what could possibly go wrong just because you guessed at whether a person was lying and you were wrong? Well, it’s all about bias.

You see, if you end up believing a person is deceptive, then, you end up with a belief-filter that might only detect information that would confirm that belief. Despite trying to keep an open mind, your brain would spend the rest of the interview reinforcing your belief that the person was guilty or lying. If the interviewee were in fact lying, the bias would be leading. However, if he had been telling the truth, the bias would be misleading.

Would it be professional or ethical to put yourself in this position as an investigator based on the toss of a coin? Let’s put it into perspective; would you appreciate it if you were under investigation and much of the outcome could be left up to chance? My guess is that you’d probably want the results to come from solid investigation as opposed to the equivalent to a hunch. 

Does Behaviour Indicate Anything?

A deviation from a behavioural baseline may indicate many things other than deception. It is leakage due to either emotional or cognitive processes in the brain and could be observed through various channels: face, body language, voice, verbal style, verbal content.

If this leakage, often referred to as a “hotspot”, is observed at a specific point in an interview, probe that area later on and raise the cognitive load of the interviewee by asking for fine grain detail. More detail gives more opportunity to compare it with checkable facts. This is the only way to truly detect deception. 

Information is the currency of deception detection. It is the clay with which to do interview pottery where a beautiful sculpture is created as opposed to an ubiquitous, pathetic little bowl. Without it, you are left with hunches and, although they might be a good starting point in isolation, they are extremely dangerous due to the aforementioned biases created. 

Learn how to interview by asking productive questions that entice fine grain detail that can be objectively assessed later. Learn how to do an investigative interview as opposed to one that literally leaves too much to the imagination. 


Next time you end up at a conference where someone tells you they can detect deception, challenge them and make them work for their money. Regardless of the letters after their name, make them cite research that is repeatable and peer-reviewed by someone other than their own company. Make them show you that they are professional and ethical. Do not let them sell you a bill-of-goods that does little for your reputation and more for their bank account. 

On an end note, if your training has made you good at detecting deception, why do you keep getting duped by the snake-oil salesman who taught you? Think about that the next time you use SCAN, NLP, BAI, BOQ or any of the other pseudo-scientific flim flam. Remember too that there are professionals out there who will judge you on your lack of expertise if that is what you show them. Stay on the side of science and be proud of your work. You owe it to yourself and the people entrusting you to find out what happened.  


Bruce Pitt-Payne retired in 2017 after 26 years with the RCMP where he was a major crime investigator and interview specialist. He is currently an internationally-recognized investigative consultant and interview trainer. He would like to pay homage to the following people who have influenced his thoughts: Dr. J. Yuille, Dr. H. Herve, Dr. R. Bull, Dr. B. Milne, Dr. A. Vrij, Dr. L. Jupe and Dr. V. Denault