I was given advice about expression based lie detection once: Don’t use it on people you know.
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Interesting. Is this because you’re more likely to jump to erroneous conclusions due to your subconscious bias, or something else?
It was a FBI interrogation expert. In his case there were two reasons: 1. if you practice, the techniques he used work and 2. it makes people (especially spouses and your children) unhappy to know that you are trying to catch them out in a lie instead of trusting them. It’s pretty obvious when you start to use these techniques in conversations, although not as obvious as pulling out a spell array.
Just using the technique suggests that you don’t trust your loved ones, but worse, accusing your family of lying in conversation doesn’t go well. He was unhappily divorced.
With respect to reliability, his position on lie detection was that most interrogators (judges, typical law enforcement, lawyers, ect.) don’t achieve better than 50/50 on detecting lies from what people think are the expression-based “tells” from lying. In fact, many people get it wrong more often than not (e.g. “he’s lying because he won’t look me in the eye”) So, using “expression” incorrectly as lie detection, can be worse than not doing it at all. Judges, in particular, can be very bad at credibility decisions based on social cues, and much worse than just flipping a coin (some only get it right 20-30% of the time, which means they are often misidentifying true replies as lies when based on body language).
But, there are expression-based techniques that can get lie detection right more often than not (it’s still not even close to 100%, there’s too much variation between people and culture). The CIA, FBI, and other federal agencies train experts in interrogation that get better than average lie detection results.
It’s mostly used to further check evidence and examine facts that come out of an interview, because knowing there is a “lie” doesn’t give you evidence. In fact, proving a lie is much different than suspecting someone is lying. As a number of politicians now know, lies are usually proven with documents, recordings, and witnesses to the lie.
I am curious why you picked the choices you did in those expression-based tells.
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You are indeed more likely to be mislead by your subconscious biases when you know the person that you’re trying to read. Also you may recognize how they feel, but not why. Making it easy to attribute it to the wrong thing.
A related anecdote in a book. The author had been in a class teaching people how to do time and motion studies. And the teacher said, “Don’t try this at home.” Afterwards the author asked…
student: Did you try this at home? If so, did it work?
teacher: When I experimented, I tried to optimize my wife’s morning routine. I figured out how she could save herself 15 minutes by rearranging chores.
student: Did your revised routine work?
teacher: It worked alright. I now do what used to be her morning routine in 15 minutes less time than when she was doing it!
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I’ll add this, because it’s common knowledge after Lie to Me aired: one of the techniques is micro expressions. I’ll frankly say that it wasn’t as reliable for me, and is more difficult to interpret. But, it is a visible thing you can watch ordinary people exhibit.
It’s a little like acupuncture though: it works on horses, but you can’t pin down exactly why.