The Lie Behind the Lie Detector: how to beat the pseudoscientific polygraph


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Back during the Watergate days, there was a technology called voice stress analysis and even machines built to use it. Reportedly, it was more accurate than the usual lie detectors in detecting falsehoods and could get results from taped conversations, which was done, as I recall, at least once on TV in regards to Tricky Dicky Nixon, the traitor.

I wonder what ever happened to that idea. Did it work? If it did, why hasn’t it been widely deployed? On the other hand, if it did work, I can understand why many people would not want to it to be deployed, especially if it can detect lies from such things as a TV broadcast.


Its cake is a lie.


I recall reading an account of someone “hacking” a polygraph by taping a thumbtack to the bottom of his big toe inside his shoe (apparently the shoe was large enough that he could walk without piercing his skin). During the test he periodically pressed his toe against the tack, causing the stress level on the readout to quickly rise on less relevant questions. The affect of this was to “bury” any nervous reaction he had to the questions that required lying.

It’s been so many years that I have no idea where I saw it, or whether it was fiction. Seems plausible. There’s probably a way to achieve the same end without risking an infection.


At some point you could buy them at Spencer Gifts and Sharper Image. No, they didn’t work, but they made a great gag gift.


I read that you can do it by curling your toes somewhere.


I don’t think so, you need a pain response to fool the machine. A little bit of movement won’t do it, that would mean you could beat the thing by crossing your arms.


I wonder if having arthritis is sufficient.


Suffering from chronic pain would probably make the result useless. Then again, chronic pain.


My Internet commentary stress analyzer* marks your comment as “very doubtful.”

But it could be wrong.

*Also known as a Magic 8 Ball


I had one of those as a kid (they were made by a local company); every time I asked it a question, the answer was “8”. Very stress-inducing.


But Tom Cruise eats a ton of it.


Funny, the answer I got was “42”.


you’re assuming just because something isn’t talked about it isn’t widely deployed


they added motion sensors to the chairs, this is much harder to pull off nowadays


It’s still in use; it’s one of the indicators investigators (and I use that term broadly — not just FBI agents and detectives, but also doctors and therapists) will use to determine if someone’s lying. That information isn’t useful in itself, but it suggests the topic needs more attention, and simply asking the same question again is often enough to get a more honest answer.

This has always been one of my favorite scenes from The Wire, and though it takes things to the absurd extreme (just like everything else in season 5, amirite?) it still illustrates the point effectively.


Xerox machines can do anything.

And yes, the bigger the lie, the more people believe it. Not just for Americans.


Ocean’s Thirteen.
Livingston Dell sneaking into a job at the shuffle machine company.


It’s still ridiculous snake oil; the Department for Work and Pensions briefly deployed it here in the UK to ‘assess’ claimants for unemployment benefits over the phone. It didn’t work and everyone hated it.