Is that a Lie?

How to detect a lie?

How can we tell if another person is telling us the truth or if they are lying to us?

Regardless if it is a partner, our child, friend, or colleague; how can we determine if what they say is really the truth.

Various studies show that the average person lies several times a day.3 There is, however, a difference between a fib to spare someone’s feelings, or a direct lie to obtain a benefit or to deliberately deceive.1

Very young children, such as pre-schoolers, are unable to lie successfully due to lack of development to realise that there is more than one perspective (theirs) on an event. As children become older, they get better at lying. They start being able to understand empathy and how another person may feel and respond from an untruth.2

A good liar needs to use words in believable and detailed ways, sometimes referring to things where they weren’t present, or that occurred. They need to be a smooth talker, able to think quickly, and have a good imagination to invent credible scenarios rapidly. Emotional control is required to convey emotions the liar may not really feel. They need to remain calm, enthusiastic, concerned, or whatever feeling is required for the lie at hand to make it sound credible.4 

The Tell-Tale Signs of a Lie

There are a few tell-tale signs of someone who is lying, and once we become educated on these signs, it is easier to detect quickly.

  1. Body language is often one of the first signals. Their eyes may wander and not look at you directly for long because they don’t want you to see they are telling you a lie. Then we have them fidgety and looking generally uncomfortable. Their behaviour is a little disjointed.
  2. Their sentence length extends. Research tells us most of us speak about 112-15 words each sentence, when someone is lying their sentence length is extended.5 Speed of voice quickens. When lying, we often talk faster as our breath becomes shallow and breathing hastens as well.
  3. Pupils dilate. A person being untruthful has pupils that tend to dilate and become larger. 
  4. Narrative of their story. We generally tell a story that contains about 40-60% of the main story facts with events. Then prior to that critical event is at 20 to 25% and the aftermath of the story usually is about 30%. If there is a considerable imbalance to this, then chances are the story is not entirely true.5
  5. Brief and simple story. The fewer facts provided are an indication of someone not telling the truth. The majority of us telling a story give some degree of details, liars usually lack detail.
  6. Avoidance of self-reference. When telling a truthful story, we usually use ‘ I ‘ to describe what occurred and what we did or said and speak in the first person. Liars tend to speak in third person conversation style. For instance, if your partner said ‘I was late home because this stupid person cut me off and I ran over something, and I got a flat tyre I had to change’ that would be accepted. If, however, they said ’A stupid person the car to hit something on the road that caused a flat tyre that needed changing’, this may be considered a story as it was said in the third, not the first person.
  7. They can’t tell their story backwards. It is a substantial cognitive load on any of us to lie backwards, we can’t really do it. If you feel the person is being untruthful, ask them details backwards such as ‘so what happened before that’ or ‘what did you say before s/he said that’. The liar can become confused and avoids due to the cognitive overload of their mind.6

So, there you have it, the ways to detect a truthful or less than honest story. Just one of these aspects may not make a liar. When we have a number of these criteria marked off, then there is a good chance, their story is not accurate. Remember, there is a difference between a fib (white lie) and a direct lie. We may sometimes tell a fib to preserve someone’s feelings or avoid hurting them. If the intent is to hide or deceive, then an untruth it is. 

Learn More

To learn more about being able to read if a person isn’t being truthful, how to detect what their body language is saying, and the way you can learn to take control of every conversation, grab your copy of the best seller book Communication Harmony now. It can change your life and place you in charge.


1, Bhattarcharjee, Y. (2017). Why we lie: The science behind our deceptive ways. National

2. Ekman, P. (2018). Learning to lie (from Why kids lie).

3. Psychology Today. (2019). What is deception?

4. Serota, K.B., & Levine, T.R. (2014). A few prolific liars: Variation in the prevalence of lying. Journal of language and social psychology. 2014

5. Rudacille, W. C. (1994). Identifying lies in disguise. Dubuque, Iowa: Kendall Hunt Publishing Co. ISBN-10: 0840391757 ISBN-13: 978-0840391759.

6. Vrij, A., Mann, S. A., Fisher, R. P., Leal, S., Milne, R., & Bull, R. (2008). Increasing cognitive load to facilitate lie detection: The benefit of recalling an event in reverse order. Law and human behavior32(3), 253-265.