The APA doesn’t seem to think so.
We have all seen a lie detector somewhere before in our lives. For most of us, it is when we are watching our favorite true crime show on Netflix. There is a lot of mystery surrounding its use and whether or not they really do what they are supposed to.
After all, there are a number of employers who use the lie detector test before formally offering a job offer. Security companies, police departments, and jobs in the federal and state government all use polygraph tests. If so many reputable employers use it in their hiring process, that means they must be accurate, right?
Well, apparently not.
The American Psychological Association states that “Most psychologists agree that there is little evidence that polygraph tests can accurately detect lies.” There is no scientific evidence that lie detector tests actually, well, detect lies.
This is because despite the fact that people would love a sure fire way to tell if someone is lying, there is no way to do that yet. Perhaps in the future, but not right now.
There are just too many variables when it comes to using such a complex machine on an even more complex person. But first, let’s look into a little about how it works.
A polygraph machine works by detecting physiological changes in a person. It mainly looks for things like an increase in blood pressure, sweaty palms, faster or shallowing breathing, and changes in pulse.
This is accomplished by hooking up little wires to your body and a machine and it sends the machine feedback. Meanwhile, the administer of the test sits behind a computer and is trained to read the results.
The administer of the test will ask certain questions where he wants you to lie on purpose. He does this to say how you act and how the machine picks up when you lie.
For example, he will ask you, “Have you ever driven over the speed limit?” Of course, we all have, and he will instruct you to say yes before he even asks the question.
Once you “lie,” he’ll compare it to his base line questions of when he know you are being truthful. This allows any lies you say during the test to be more easily interpreted.
Now that we have some idea of how it works, let’s look at some reasons as to why it’s not always completely accurate, if ever.
Because the machine measures physiological changes, as long as a person keeps themselves cool, calm, and collected, there won’t be any charges in a person’s body.
In this sense, they could be lying without the machine actually picking it up. There would be no changes for the machine to read and thus it would say the person is being honest.
This one is a little more complicated, but it’s another way a person can out smart a lie detector test.
They can do this by over reacting to the questions where the examiner asks him to lie on purpose. Let’s go back to our previous example of being asked “Have you ever driven faster than the speed limit?”
If you clench your fist or inhale sharply on purpose and then answer, the machine will pick this up. So if you lie during the real exam but only give off a slight change in your body, the test will have a harder time declaring it a lie.
It’s a smart little trick if you think about it. Essentially, you over sell yourself and do something on purpose to clearly show you are lying during the base questions. Then, as long as you don't do the obvious signs that you did earlier, even if you are lying, you should come out as truthful.
It can can also go the other way. A person who is being honest can be deemed a liar by the test.
As stated earlier, many security, law enforcement, and government jobs require a lie detector test. These can be stressful jobs to apply for, and no doubt anyone who applied would be nervous.
Because of these natural nerves, people can fail the test even if they are being truthful. Maybe they overthink a question or answer one way but then remember a couple years ago they actually did the other thing. A person may start to lose control a little and thus have physical changes.
As you can see, the lie detector test is not accurate. You might now be thinking, so why are they still being used by such big and well known agencies?
I personally think they use them as a form of intimidation. They would much rather a person over tell than under tell in these lines of work. They want to know every and any bad thing you ever did, even if it was as small as stealing a pencil from work.
By using the test on applicants, they can also see who can withstand the pressure and who can’t. I’m sure this is a vital trait to have in a career like law enforcement.
So, if you ever need to pass a lie detector test, hopefully you can remember what I wrote here today. Stay calm and poised and you will have no problems.
Unless you really are a bad guy, then I hope you ignore everything said here.
