Have you ever been able to tell that someone is lying by their facial expression or external movements? Well, many of these external cues can help to determine whether or not a person is actually lying. The Fox show, Lie to Me (aired from January 2009-January 2011), used applied psychology to determine if people were lying by analyzing their facial expressions and body language. In the show, Dr. Cal Lightman (Tim Roth) would carefully analyze suspects facial expressions and body languages and be able to determine if, in fact, they were lying, or perhaps even telling the truth. Tv.com describes Cal Lightman and his team as a "human polygraph machine, and no truth can be concealed from them."
Our textbook explains that the polygraph test, or lie detection test, relies on what is known as the "Pinocchio Response"- a perfect physiological or behavioral indicator of lying (419). The CQT, or Controlled Question Test, is the typical format associated with the polygraph test, and it asks three types of questions: relevant questions (having to do with the crime), irrelevant questions (don't have to do with the crime), and control questions (probably will produce lie, in order to determine a baseline for measuring bodily responses that are lies).
However convincing the polygraph test may seem in movies or television, there has been convincing research that the polygraph may not be as reliable as we once thought. According to our textbook, the problem with the test is that it confuses arousal with evidence of guilt. It's basically an "arousal" detector as it measures increases in blood pressure, respiration, skin conductance, and palm sweating. Although these may be indicators of lying, a suspect may show signs of all of these responses not because they are guilty, but because they are nervous about being questioned about a crime they didn't commit.
You may be wondering, as I was, if the polygraph test is invalid, why do people still us it as a means of detecting lies. Well, it turns out the test is actually effective in making suspects confess to their crimes...especially when they fail the test.
The use of polygraph testing in court is extremely controversial due to the mixed results they often produce. The United States Supreme Court deemed individual courts jurisdictions to be responsible for determining if a polygraph test should be used as evidence in cases. Interestingly, in five states (Iowa, Massachusetts, Maryland, New Jersey and Delaware) it is illegal for an employer to administer a polygraph test to an employee that is suspected of committing a crime while on the job.
I always thought polygraph tests were really interesting as I recall seeing them on news reports on TV and by watching Lie to Me. I think it would be very interesting to watch a polygraph test be administered, or even to take one! What are your thoughts?
Check out this trailer for the show Lie to Me, starring Tim Roth as Dr. Cal Lightman!