Human Lie Detector

4.9 based on 7 ratings

Updated on Jan 17, 2013

When mom asks if you brushed your teeth, do you always tell the truth? How about when your teacher asks why you didn't finish your homework? Did your dog eat it? If you’ve ever not told the truth before, you told a lie!

Now don’t be ashamed: everyone has lied at least once. But did you ever wonder if people can tell when you lie? If they could, that would be embarrassing. Let’s find out if there is a way to tell a truth from a lie.


Is there a way to detect if a person is lying or not?


  • 3 children volunteers
  • Notebook
  • Pen


  1. Chat with one volunteer at a time.
  2. Ask the volunteer to tell you three statements that are true and three statements that are lies.
  3. Pay careful attention to your volunteer as they talk.
  4. Write down details about facial expressions, motions, or tone of voice during each statement.
  5. Using the details from Step 4, write down your guess, often called a hypothesis, at which statements were false.
  6. Instruct the volunteer to tell you which statements were true or false.
  7. Record which statements were actually true or false.
  8. Repeat steps 1 – 7 with each volunteer.
  9. Look over your data. Were the results what you expected?


If careful enough attention was made during steps 3 and 4, you should have been able to tell most of the lies from the truths. However, results may vary due to everyone having different ability in being able to lies.


Lies can be easily detectable for some people, but not all. When lies can be detected, they are usually told by people who seem nervous or anxious. Research has shown that people tend to act differently while telling lies because their emotions overpower them, causing them to have “tells”. Tells are motions such as eye movement, fidgeting, licking lips, and rubbing palms. They signify lies because it acts as a mean to remove stress. Every person has a different kind of “tell”. In order to figure them out, you must know how they act normally.

There are machines called “lie detectors”. These machines monitor your heart rate, slight movements, and other things that one may do while being questioned. However, even these machines are not completely accurate. The best liars will show no difference between truth and lies. What if we changed the volunteers being questioned? Would being an adult affect how lies are told? There are other ways to test this theory, go and experiment!

How likely are you to recommend to your friends and colleagues?

Not at all likely
Extremely likely