According to nolo and manyothersourcesincluding Cecil, they’re far from foolproof. Additionally there is a lot of advice out there on how to “beat” a polygraph test. I’m guessing that a lot of factors come into play - the skill of the tester and the attitude of the testee in particular.
I’ve only ever taken one, during a job application. That was almost 30 years ago and I don’t recall details, but I do recall that a couple of my entirely truthful answers were flagged as not entirely true. And one minor lie I told wasn’t flagged. (I got the job.)
Given the disputed reliability of them, how often are they used in job screening, and how much weight is typically given to the results?
There is no such thing as a “lie detector machine.” There are machines that measure heart rate, blood pressure, breathing etc. The assumption that these factors can be used to determine lies has not been demonstrated.
I only know about the use in job field, which is that my wife has had to take them before doing volunteer police work.
The polygraph is not the only thing they rely on, and they follow up on any unusual results by asking you to elaborate. To some extent, they’re looking for obvious contradictions with your other information. For example, you say “I’ve never done drugs” but there’s a 20-year old arrest for drug possession. In that sense, the polygraph is as much a psychological intimidation tool as anything else. If you have something to hide, you’re more likely to 1) not apply for the job in the first place, 2) make mistakes that can be spotted or 3) admit to the truth up front.
I certainly wouldn’t want to trust a polygraph, nor would I want to trust somebody who relied on one. Years ago I worked for a defense contractor, and they got a project that required a special security clearance. My boss’s boss wanted to put me on the project, and they sent me the paperwork to fill out for the security clearance. One of the stipulations in the paperwork was that I would agree to take a polygraph test at any time. Bzzzt… Not happening.
So my boss asked me why, and I told him that I didn’t trust polygraphs, and then I had a long talk with his boss. He was trying to sell it as “well, they aren’t going to ask invasive personal questions or anything”, but I wasn’t having it. He finally asked me what the big objection was, so I put it like this: What if they ask me to take a polygraph, ask me if I’m selling secrets, and I answer no but the machine and/or operator says I’m lying? What happens then?
“Well, they couldn’t prosecute you or anything, they’d probably just pull your clearance and take you off the project.”
Right… Probably right about the no prosecution thing, but I’d have had any number of government agencies living up my butt for a very long time. I’ll pass, thanks. Fortunately it wasn’t a job requirement that I took that project, there was plenty of non-clearance related stuff I could do. Declining to take that probably cost me any chances at advancement there, but that wasn’t really a goal I had anyway.
I think the polygraph as a machine is about as accurate as the 25 cent “love indicator” at carnivals.
However, used as a tool in the hands of an effective interviewer, who can play on people’s inherent nervousness, the interviewer is probably much more effective.
I’m seeing it make sense as a tool, although not a very effective one.
The one issue that I told the truth on but the device registered me as lying about was something to do with the last time I’d used illegal drugs. Upon questioning me further about that, the interviewer said that I might have some nervousness or stress when talking about doing something illegal, and the device picked up on my physical responses to that.
All a polygraph does is raise flags, that maybe certain things need to be investigated further or elaborated. That in fact is how is real life most lies are “detected” without polygraphs, a questioner deciding that a certain answer seemed off somehow, and investigating further.
So its just the mechanical version of the bullshit detector.
I used to work at a small company that sold medical sensors and software. As low man on the totem pole, I was the one hooked up to sensors when we needed to demonstrate them or train some one.
Polygraphs are worthless at detecting deception. They are great at measuring stress IF AND ONLY IF the subject is not trying to alter the readings.
Well, they’ve been called ‘lie detectors’ for as long as I can remember. Nobody officially calls them that anymore and I’m guessing that is because the people who use them got tired of getting called out on the name. Google ‘polygraph’ and there will be plenty of entries that say ‘polygraph (lie detector)’ and there are number of ads for certified lie detectors that link to actual polygraph companies.
I’m reading one such site now (NYPOLYGRAPH) that carefully makes no claim of any kind except that they are used by many reputable companies (they have an impressive list of clients.) If a test makes no claim about what it measures, why would anyone use it?
In cases where a trained professional uses the detector and proper interview techniques against an average person, where the results of the test have the potential to actually impact the person’s life, the accuracy rate is something like 92% (if I remember right).
In cases where you test the polygraph on people who have nothing to gain/lose depending on the results of the test, it’s not a useful tool.
In cases where the target person has received even minimal training in possible methods for “beating” the test, then the usefulness of the test entirely depends on whether the interviewer notices and is able to prevent the subject from using those techniques.
So, it’s unlikely to be of particular use to the CIA for anything they do. But for your average city cop, using it against the lowest common denominator, it can be a reasonbly effective tool. (Granted, an 8% failure rate is still pretty significant.)