I know we all know that polygraphs don't work, but: is that true in practice or in principle?
I mean, there are papers out there about methods capable of extracting complete words from brainwaves. Does it really seem impossible for a machine with current tech to detect signals of lying with high certainty?
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It works the other way around: polygraphs need to show that they work in replicated, controlled experiments.
That hasn't happened[1].
Lying is a complex behavior. Like, really complex. Even with all of modern technology, we've only just started to detect far more gross brain functions: pre-speech motor patterns, fear responses, etc.
It goes without saying that an MRI is at least slightly more complicated than something you could knock together in an afternoon after a shopping trip to Radio Shack in 1963.
Polygraphs are a $2 billion industry, and Upton Sinclair said it best: "It is difficult to get a man to understand something, when his salary depends on his not understanding it."
"I mean, there are papers out there about methods capable of extracting complete words from brainwaves"
As far as I know, this is complete fiction right now. Same with images.
There are people currently working with AI interpreting brain signals to be reproducible, to say, move left and right in a game. It's far from working on "left" / "right", let alone anything more sophisticated than that.
There are researchers using functional MRI (and machine learning presumably) to try and detect lies. There may even be some trying to use it commercially.
I imagine it's about as reproducible as most fmri research, as in not.
I think at some point you might be able to detect lying with high accuracy given a DNA sample, a high resolution/high fps camera pointed at the person's face, and a vocoder-generated questioning regime.
However, it would be very expensive to develop the training data for such a system, and it might not work on rare ethnicities. Or other abnormal people, like autists and evil geniuses.
I think a good liar is just exceptionally good at convincing themselves that what they're saying is the truth. I think that even better liars are so narcissistic that they basically believe what they say as it's coming out of their mouth, on account of it being them that is the one saying it.
I say all of this as a horrible liar.
There are a lot of different ways to lie, and the method you point out is one of many.