Polygraph Tests and Lie Detection

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The process of lie detection is pretty self explanatory; it is the act of determining whether a person is lying or not. Polygraph tests are what are used to detect lies. But are they really effective?

The polygraph test measures blood pressure, respiration, pulse, and skin conductivity. During the time when the person being tested is hooked up to the polygraph machine, the examiner is asking questions to the person being examined. The more of the four previously stated symptoms that are shown while the accused is answering a question, the more likely it is that he/she is lying in their response to that certain question. When humans lie, we have a tendency to breath faster, have higher blood pressure, faster heart beat, and we tend to perspire; especially in the hands. Click this link to see a video on how a polygraph machine works.

The polygraph machine consists of a computer(or a machine recording the data), a blood pressure cuff(to measure blood pressure), galvanometers(to record skin conductivity), and pneumographs(to measure rate of breaths taken).

Sure, these tests do provide us with some information as to whether the person is lying or not; but we can't be sure that this information is credible. Most scientists consider lie detection to be a pseudoscience. It is said that the polygraph tests are entirely correct only about 5-10% of the time. This is a prime example of replicability and falsifiability; replicability because after the first test with the suspect, they may learn how to fool the test, as there are many ways that are thought to deceive the polygraph machine. And falsifiability because the tests have been proven to be false representations of the truth, but also have been proven to work as well. Here are a few ways that people claim to beat a lie detector. Try as they might to deceive the test, a skilled polygrapher can detect these attempts. Check out this video to get a better idea of how polygraph tests are administered and how lies are detected on them.

Although these articles and videos prove that lie detector tests do work, I would like to know a few things about them. First off, why, if they work so well, don't we use them more often? Are there other reasons for why some people truly believing in the tests, while others are on a drastically opposite side? Do the tips on beating the test actually help, or do they fail, like in the video?

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You might want to look up the meaning of falsifiability in your text again. Good use of outside resources.

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This page contains a single entry by mosco015 published on November 6, 2011 10:28 AM.

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