'Non-Invasive Polygraph' Uses Infrared Light

opticsorg writes "Infrared laser pulses could soon be used to determine whether someone is telling the truth or is under stress. In patent application WO 03/057003, US firm Defense Group describes a non-invasive polygraph machine that fires infrared pulses at the subject. The reflected and scattered pulses are gathered and analysed by a receiver. 'The receiver is connected to an information processing device capable of determining various physiological characteristics exhibited by the human subject,' say the authors." Whether "various physiological characteristics" are reliable signs of truth-telling is another issue, though.

Polygraph story

[Laplace]

So I knew this woman, a world class athlete, who also worked for the Department of Defense. For her Top Secret clearance she had to submit to a polygraph test every six months. On the day of one of her tests she arrived at the testing center having just worked out. Her pulse, respiration, and skin moisture were all a bit elevated, and the tester noted these abmornal readings to her. Now, one of her training techniques involved meditation, and she became adept at both mentally and physically relaxing in a very short amount of time. She went into her meditation routine and almost instantly her pulse and breathing rate dropped. The tester became angry with her, and told her to come back the next day. Now how hard can it be to learn to game the whole polygraph system?

Re:Polygraph story

[Sylver Dragon]

Sorry, bit of a typo there. Though I still stand by my assertion polygraph tests are junk science. If you haven't done so, I would recommend reading The Lie Behind the Lie Detector [antipolygraph.org] (PDF), its a good read and very informative about polygraph tests and the like. Polygraphs are just the moden day version of a mystic. They don't do anything in and of themselves, they only convince people to confess, and are great for destroying someone's credibility because the media believes in them.

Re:Since when were standard polygraphs invasive?

[schlyne]

Supposedly, the retinal imaging section of the test is more reliable. If the pupil dilates suddenly, the person is lying.

Great

[joelt49]

Great, another machine to do the impossible. I mean, really, how is this different than just looking someone in the eye when you ask them a question? Some people can lie convincingly and others can't. That's all there is to this system. Once you have a system, you CAN beat it, and some people do. Why don't we just accept that fact and get rid of polygraph machines? Either that, or have an experienced poker player read the results, as they have TONS of experience with poker-faces.

An alternative to classic lie detector

[FrankoBoy]

is found in new techniques involving brain scans. A brain wave pattern called P300 ( "positive wave" 300 ms after onset ) has been discovered to be activated when a person looks at a familiar object ( the P300 hypothesis has gained very solid evidence since a few years ). So you can display some pictures to the accused person and embed in these actual crime scenes pictures, and then tell if the accusee is familiar with crime scene pictures ( like what the place looked like, weapons involved, etc. ). Of course, you have to display pictures that has not been released to the media and whatnot, but the uniqueness of the combinations needed to figure out that someone is involved in the crime is pretty high. Links here [nationalgeographic.com], here [sciscoop.com] and here [registerguard.com].

This polygraph stuff got to be thrown away at some point anyway, since it's based on reaction patterns that many people just don't have so its accuracy isn't high enough for the important task it has to do.

Different path

[Armbrust84]

I just wonder if there is anyone out there who is combining the new insights we gain each week into the workings of th emind with the newest theories and practices of forensic investigation. Seems to me that we cannot rely on only one method. Although, ever more frequently, the police require less evidence to arrest, and judges/juries even less to convict. Oh well, I pity my great-grandchildren.