Polygraph, Schmolygraph.

Even though I’d argue that its impossible to find anyone that fits the mold perfectly when it comes to our society’s view of normality it doesn’t deter me from the pursuit of understanding it. There are a lot of norms out there that don’t make logical sense and as an engineer this becomes a curiosity, as I try to figure out these norms and map them out with easy input/output equations in my head. This sounds a bit abstract and I tend to normally describe this as “trying to understand the everyman” which has the subtle undertone of me being an outsider. I’ll put that down to my awkward teenage years still being a fresh memory 😉

Coincidentally this pursuit of understanding will usually clash quite heavily with the skeptical voice inside me. Things that don’t make sense or aren’t based in sound science and logic form a large part of our everyday norms. One of these is the perpetual myth of the Polygraph, which reared its head in a recent political scandal that hit the news this morning:

“As a first step to restoring my reputation I subjected myself to a lie detector test and the results are set out in the report dated 29 January enclosed with this letter,” the letter said.

“Despite your denials, you will see the result is conclusive. You cannot be surprised.

“I am providing you with the results of the lie detector test because I want you to publicly admit that I was telling the truth about our relationship.

Now I’m not going to comment on whether or not this story has any facts behind it (to be honest its your usual political scandal/beat up, they’re a dime a dozen) but the use of the polygraph is what got me listening. Taken on face value the results show that she wasn’t lying about the relationship in question and thus puts pressure on Rann to take the test to either prove or disprove the results. This however is one mistake that the everyman has been making for a long time, trusting the polygraph.

Most people in any modern society are familiar with the idea of a polygraph or “lie detector”. In essence its an information aggregator taking readings of bodily functions like breathing rate, respiration, pulse and other metrics like skin conductivity and blood pressure. The measures themselves are objective and quantifiable however the interpretation of them is far from it. In fact the scientific community’s consensus on the polygraph is that they are unreliable and not much better than random chance. So why are they still brought up so often in circumstances like in the article I linked above?

The most obvious reason I can see for this is the lack of education. Ask anyone on the street what the wider scientific community thinks on polygraphs and I’m sure the majority of answers will be along the lines of “I don’t know”. Scandals and their use in popular media don’t help this fact either as the majority of them fail to mention the failings of the polygraph, instead only demonstrating their use. It also doesn’t help that one of my favourite shows, Mythbusters, perpetuated the myth with their use of a discredited polygraphist and liberal interpretation of the scientific method. Don’t get me wrong though, they’ve done more for the world of critical thinking than many others have, but this is one point in time where they failed terribly. There are counter examples to them though, like those with Penn and Teller’s show Bullshit, where they aptly demonstrate the polygraph’s failings and show you how to beat it in under 10 minutes.

The good news is that in most courts around the world polygraphs are inadmissible and in our own backyard they’ve been aggressively thrown out, setting the precedent for all cases henceforth. Still they prevail in popular media mostly as an attempt to generate more controversy because their ambiguous nature makes for a good story. It’s a testament to the times that I only see a story like this once every year or so but it will still be a long time before the everyman knows that polygraphs are pure bull and should be discounted as such.

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