Want to know if somebody is lying? It’s always so hard to tell. [dbmaking] has whipped up a fun little polygraph, otherwise known as a lie detector. It’s nowhere near as complex as the ones you’ve seen on TV, but it might be just as good when it comes to finding the truth.
The project keeps things simple by focusing on two major biometric readouts — heart rate and skin conductivity. When it comes to the beating heart, [dbmaking] went hardcore and chose an AD8232 ECG device, rather than relying on the crutch that is pulse oximetry. It picks up heart signals via three leads that are just like those they stick on you in the emergency room. Skin conductivity is measured with a pair of electrodes that attach to the fingers with Velcro straps. The readings from these inputs are measured and then used to determine truth or a lie if their values cross a certain threshold. Presumably, if you’re sweating a lot and your heart is beating like crazy, you’re telling a lie. After all, we know Olympic sprinters never tell the truth immediately after a run.
Does this work as an actual, viable lie detector? No, not really. But that’s not just because this device isn’t sophisticated enough; commercial polygraph systems have been widely discredited anyway. There simply isn’t an easy way to correlate sweating to lying, as much as TV has told us the opposite. Consider it a fun toy or prop to play with, and a great way to learn about working with microcontrollers and biometric sensors.
This is effectively an E-meter if held in each hand?
I really do wonder how they were made before digital ICs or perhaps they were never analogue
An e-meter is nothing but a simple lie detector.
They were analog. Very easy to make. It is nothing but an overly complicated ohmmeter with a knob to set the reading to zero. Deflection from zero means a lie.
Lie detectors and e-meters respond mostly to how much you are sweating – which can change due to lies, but can also change for a zillion other reasons.
“Want to know if somebody is lying? It’s always so hard to tell.”
Not always, just watch any speech from the current Pervert Of The US. Unless you’ve protected yourself from the deadly 5G truth rays by donning a red MAGA hat then you’ll probably know quite quickly. If the big orange baby’s burger ingress port is open and making noise then a lie is almost certainly not far behind once you’ve decode the infantile ramblings.
How can you tell if any politician is lying? When their lips move.
Old joke, but still pointy.
Can this device be connected to a TV to indicate the bias level and accuracy of certain “news shows”? I do not quite remember the exact name of such a “show”, it’s on the tip of my tongue, it sounds a bit like Samantha Fox and screws although I can’t remember what Sam had to do with construction but I digress. I just want to connect it to my TV, that’s all.
Catching people lying is easy, as long as you don’t mind a lot of false positives.