DIY Lie Detector
Police use lie detectors to help determine if a person has told a lie about committing a crime or is lying to cover the acts of another. However, police do not rely solely on lie detectors when investigating suspects, but also rely on body language, eye contact and vocal clues from the suspect. Polygraphs, which aren't even admissible in court, simply measure the sudden rises of heart rate when a person verbalizes a lie. Instead of building a complicated device, you may rely simply on a stethoscope and body clues to indicate a person's attempt to deceive.
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Instructions
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Watch how the person in question reacts to you when they speak. According to former CIA agent Lindsey Moran and New York Police Department officer Derrick Parker, when someone tells a lie, they typically avoid eye contact. Ask the person to look you in the eye when they speak. If they look away, this could indicate lying.
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Examine the person's body language as he speaks to you. Parker suggests that a person telling a lie does not stand, sit or seem confident at all. Often times they will shift from one foot to the other or seem shaky and nervous when telling the lie.
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Pay close attention to whether the suspected liar has sweat on his face or elsewhere on his body. Parker suggests this is another body language clue of a person's dishonesty. While you may have trouble detecting this in heated areas, sweating instantly in an air-conditioned room may indicate the person's dishonesty.
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Listen for the lack of detail in a suspected liar's story. Liars often create their lies on a whim, without giving the lie much thought. If you ask the suspected liar a question and get a simple answer that lacks detail, prod for more details and you may cause the liar to slip up and give away information you know for a fact to be a lie.
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Listen for momentary pauses when you suspect you may be hearing a lie. People attempting to tell a lie will often pause momentarily in their sentences to think up details to the lie in attempts to make the lie more believable. These momentary pauses give away the person's attempt at deception.
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Watch for rude behaviors. According to psychologists Wendy Morris and Bella DePaulo in their book, "The Detection of Deception in Forensic Contexts," liars typically express more rudeness and complaints when lying than expressions of pleasantness and friendliness. This may occur because the liar is hoping their anger will fool you into believing they are only angrily attempting to defend their truths.
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Examine the suspected liar closely for small signs of lying. DePaulo and Morris agree that liars often exhibit rises in vocal pitches and sudden dilation of the eyes when vocalizing a lie.
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Check the suspected liar's story by asking that they repeat the tale. Police often use this ploy to help weed the lies out of a suspect's story by seeking inconsistencies when the suspected liar repeats their tale.
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Examine the suspected liar's pulse when possible or applicable. While employees, coworkers, your boss or acquaintances may not agree to this, you can use this method to detect lies among your children or significant others. Hold your forefingers against the person's wrist or use a stethoscope to listen to the person's heart rate. If you hear or feel an increase in pulse or heart rate, you may assume--but not be certain of--the person's lack of honesty.
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Tips & Warnings
These steps do not always indicate a lie, but may help you to make the liar nervous enough to confess to his lies.
You may have difficulty detecting lies using these methods or any other methods when speaking on the phone or reading typed or written messages.
References
Resources
- Photo Credit girls talk image by Galina Barskaya from Fotolia.com
