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Catch a liar with a homemade polygraph test

Filed Under: electronics

Make A Lie Detector! - The most amazing bloopers are here

A polygraph or lie detector test records a subjects physiological responses while answer a series of questions. Do they tell necessesarily if somebody is lying? No. They do however notify the tester when the person exibits signs associated with the physical changes the occur when somebody is lying. This homemade lie detector isn't nearly as scientific as professional grade machines, nor are you a trained test administrator. Still, if you're looking to have a little fun, build a working polygraph machine and catch a lier then you'll enjoy this project.

The circuitboard assembly looks fairly complicated. You'll need some understanding of electronics, but the video has a helpful diagram and instructions. The video also shows this homemade polygraph in action. It measures the skin resistance which goes down when the subject is lying. If you want to back up your test with some behavioral science, check out M.E. Williams post on How to catch a liar in the act. I wouldn't do anything drastic based on the results of a homemade test, but it does sound like a fun experiment. Maybe you'll find out what people really thought of your Thanksgiving dinner?


  • Bekah

    I am doing a science fair project for my school and i want to make a polygraph machine and i was wondering if i could have written out directions to make the type of polygraph test machine that was displayed on the video or just a supplies list. If you could do that it would be great help!!!!

  • Francesca Clarke

    Hi Bekah,
    This would make a great Science Fair project, but it' not a simple one! They do say that you'll need some background understanding of electronics. The supplies are all listed in the video. They include a diagram too, so that should help with the assembly. You'll probably want to slow it down, and follow it step-by-step, but there is loads of information in the video.
    Let us know how it goes!

  • K T N

    can u Describe in detail how we would make the circuit board again

  • K T N

    sorry to bother u but this is for a science fair. can you explain everything about the electronic circuit in detail

  • harry

    im new to these transistors and other components where can i find those if at home in what appliance if at store where. this is for a science fair project would love to try this out


    My Husband has been lying about an affair. He stays the night at work 2 to 3 times a week.

  • 6 Comments / 1 Pages

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