Can an Innocent Person Fail a Polygraph Test?

People generally fail a lie detector test for two reasons: either they are lying or they are innocent but their reaction is similar to guilt. Scientific studies have shown that sometimes an innocent person’s reaction can mimic that of a guilty one.

So, can an innocent person fail a polygraph test? Your answer is yes, they can.

What Does it Mean to React Similarly to a Guilty Person?

When a person is guilty of lying, they give tiny signs that the polygraph picks up on and highlights. These include fidgeting, increased heart rate, palpitations, heavy breathing, and dilated pupils. For various reasons, sometimes the innocent can react in the same way, because of anxiety or nervousness, resulting in a failed test.

Reasons Why an Innocent Person Might React Like a Guilty One

There are several reasons why an innocent person might react like a guilty one.

  • The person is nervous or anxious about being questioned.
  • They were the victim of a similar crime and the test brought back those memories
  • They are guilty of a different but similar crime or behaviour
  • The person in question was indirectly involved in the act but didn’t actually commit it. They could have helped in planning or knew about it but kept quiet.
  • They know who committed the crime and is protecting that person
  • They misunderstood the question and reacted to that

Can a Lie Detector Make Mistakes?

Lie detector machines are not perfect. According to some researches, lie detectors are only 90% correct. That means that their error rate is usually 10%. So, 10% of innocent people will be deemed deceptive.

Should You Take a Lie Detector Test?

There is no hard and fast rule to decide whether you should or shouldn’t take the test. To take an accurate polygraph, you should be aware of the allegations against you. You should know the specific details and not just someone from your past that is claiming you sexually assaulted them or any other generalized claim.

If you are undergoing chemotherapy or taking certain medications, you can’t take a polygraph. Moreover, drinking and intoxication might affect your test results. So, can an innocent person fail a polygraph test? Certainly.

Moreover, there is no benefit to taking a polygraph test if the prosecutor’s office will still issue the charges if you pass. So, only agree to take the test after you have an agreement in writing saying that you will not be charged if you pass.

Sometimes the polygraph is also used as an interrogation technique by police instead of a legitimate method of seeking the truth. In this instance, the polygraph test can work against you.  So, it is vital to know whether the test is being given to determine the truth or is being used as an interrogation technique.

If you have been asked to take a polygraph test, contact your lawyer first. Ask them if it is worth agreeing to and whether it will help your case. A seasoned criminal lawyer will help you make the right decision.

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