The lie detector: You decide if it works!
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- čas přidán 8. 07. 2024
- Cat and Ale demonstrate a 'lie detector' and you can make up your mind if it actually works. Watch the clip and discuss below how many truths and lies where in it.
We have measured skin conductance (voltage divider 10M vs fingers), pulse rate, ECG, blood oxy and oscillometric blood pressure.
Pay close attention especially to the movement artefacts in all channels.
Want to know if you've been right/wrong? Check it out here: www.biosignals.org.uk/interpre... - Věda a technologie
Years ago I volunteered to take a polygraph examination as part of a classroom demonstration. Even under those circumstances, I felt anxiety and stress. I was instructed to lie as much as I could. All the lies were detected. This mock test left me with a respect and fear of the polygraph.
I recall a woman who applied for a job working with children. A polygraph exam was required as part of her back ground check. She is a bigger than average woman and the standard size blood pressure cuff was too small for her arm. A large adult cuff was used and it may have been a little small too. The result of her test was inconclusive. The examiner told her that the cuff size may have effected the test. She told me the test was very stressful.
A polygraph examination can be summed up in three words: anxiety, stress and fear.
The cuff used during a polygraph examination is like the one used in the medical setting. However, the polygraph cuff measures blood volume in the brachial artery. If you placed a stethoscope below the cuff on this woman you may hear the Krotkoff sounds. If her heart beats more forcefully, the blood volume will increase and will show up on the graph.
The software was comedirecord (runs under Linux). The screencapture app was ffmpeg. The edit was done in Sony Vegas 12.
What program(s) were you using in this demo?
I had a polygraph examination three weeks ago. It took almost three hours and was very stressful. When I got out to my car I started to cry. Four days later I was notified I had passed.
Most modern Polygraph equipment includes a foot pad that detects movement. If a woman is being examined she will be asked to remove her high heels if she is wearing them. This is required because your feet have to be flat on the the pad. So ladies if you are scheduled for a polygraph examination, wear flat shoes. And stay as calm as you can. Best of everything to you.
What is ecg, obp and skin conductance rate if a person lie? Is it increased or decreased n how much can b the rate
Being connected to the polygraph is a very stressful experience. When that cuff starts to tighten on your arm and your heart starts to beat like a trip-hammer, you can't think straight. The room seems like it spinning. Hope you never have to take one.
Had a polygraph last month, and yes I had to remove my high heels
I would like to make some additional comments about the polygraph. Most polygraph examinations today have you sit on a pad and have you place your feet on another pad. These pads detect movement. You have to sit perfectly still during a polygraph examination. If a woman comes to the exam wearing high heel pumps, she(as I was) will be asked to remove them so her feet will be flat on the pad. The polygraph experience plays up the fear factor. There have been cases where a person confessed just by seeing the polygraph. I like to think of the polygraph as a psychological physical exam. Some of your vital signs are being watched by a perfect stranger. You are really at they're mercy. Some individuals have told the truth and failed an exam. Others were told that the results were inconclusive and agreed to be strapped into the chair again. When reporting for my third polygraph, I passed a woman who had just been examined. She had that far away look on her face. When I finished mine, I probably looked the same. The polygraph will no doubt be improved as time goes on. But the element of fear along with the anxiety and stress will always be there. The whole process is really quite humiliating. I have wondered if some of these examiners get some type of enjoyment out of it.That would be an interesting area for study. But would they tell the truth? Only the polygraph would know. Thanks again for this video.
And there have been cases where a person was attached to the polygraph, the stress became too great for them, and they confessed. This happened to one woman. She thought she could "beat" the polygraph, but had second thoughts just as the test was starting. She felt the blood pressure cuff inflate on her arm and then told the examiner to stop. She wanted to talk. The "fear factor" worked and the polygraph claimed another victim.
+BPM biosignals
I totally have
trouble believing that this test works, because some people happen
totally falsified the results, how to see that the person lies? When she lying blood pressure increases? How do you see on the blood pressure graph that the person lies?
It was easy to see where she was lying. The blood pressure cuff gave her up.
I think sitting in the chair, after you have been attached to the machine, caused me to feel great anxiety. Then you feel the pressure cuff inflating on you arm. You heart is beating like a trip hammer. There is about a thirty second pause and then the questions begin. You can almost hear you heartbeat. Stressful.
This is of course a very basic way to show how the polygraph works. The emotion that the vast majority of people feel when they know they are going on the polygraph is FEAR. I worked for a government agency for five years and was polygraphed eight times(including my pre-employment). Not knowing when you are going to be tested, makes you think twice about doing something wrong. When you enter the room where the examination is to be administered and you see that machine and you feel anxiety, nervousness and stress. And you know you haven't done anything wrong. I never got comfortable taking a polygraph examination. I felt the same emotions on the last as I did on the first. Getting attached to the polygraph can be a little embarrassing when the examiner has you lift you arms over you head so the breathing tubes can be applied on you abdomen and chest(above the breasts). As seen in the video, sensors are attached to measure skin perspiration and pulse rate. Finally a blood pressure cuff is wrapped around one of your upper arms. The test begins when the examiner pumps up the pressure cuff, waits for about a minute(it seems like an eternity) and then starts the questioning. The BP cuff can become a little uncomfortable after a while(notice the bulge on the upper arm of the women being questioned) and a good examiner will pause the test and deflate the cuff. The cuff is usually inflated to 70 or 80 mmHg. On this video, I don't know if you could detect deception on the subject. Since my examinations, I have learned that blood pressure fluctuations help the examiner the most in detecting deception. Some have attempted to control they're breathing and that may have worked, but you can't control your blood pressure. Its your heart against the cuff. I passed all of my polygraph examinations because I told the truth and I had professional and honest examiners. If I had to take a polygraph again I know I would feel the same emotions and I would be scared. That is what the polygraph does to you. Thank you for making this video and educating the public about the polygraph.
her blood pressure was all over the place.
Heart rate is high.she fear