Posted in Psychology & Medicine

Lie Detection

In developmental psychology, a child’s ability to successfully lie is considered a milestone achievement. This goes to show how lying is one of the characteristic behaviours of human beings. Even a three-year old knows that by lying, they can avoid punishment and gain much more.

There are many signs of deception. Becoming an expert in observing these signs and knowing what they mean can grant the ability to see through lies. The following is a description of some of the changes – both non-verbal and verbal – that people exhibit when lying. Note that these signs are not always definitive and should be used as a reference only. One must carefully deduce whether the signs are there because the person is lying, or whether it is a simple physiological process with no meaning. Here is a simplified list of the signs that will be discussed:

  • faster blinking, avoiding/too much eye contact, dilated pupils, looking up and right
  • sweaty face and palms, fast pulse and blood pressure, flushed face
  • dry mouth/lips, constant licking or pursing lips, swallowing loudly and often
  • looking away or down, tics and twitches in face (eyes, cheeks, mouth)
  • placing hand near mouth (rubbing nose/chin, scratching face etc.)
  • touching neck, pulling at collar, rubbing forearms or hands
  • shoulder shrug, crossed arms/legs, fidgeting, hiding of hands
  • holding hands or clenched fists, unusual movements
  • tucking feet below seat, tapping of feet
  • short, general descriptions (or overly detailed), inconsistencies in detail
  • talking faster and at a higher pitch, emphasising the “truth”

Non-verbal signs are essentially body language – a mean of subconscious communication through which the person signals to another person about their emotions and thoughts. These can be behavioural (avoiding eye contact), physiological (faster heart rate) or cognitive (exaggerating that they are “truthful”). As non-verbal communication makes up 90% of a conversation, it is extremely useful to know what signs to look for and know what they mean. Let us start with the face.

The eyes are considered the window to the soul. This is because the eyes give off so many clues about what the person is thinking, usually subconsciously. A key sign to look for is the frequency of blinking. If the person is blinking much more than usual, it suggests that they are nervous (causing their eyes to dry out faster). Another famous example is eye contact – people avoid eye contact when lying as they are subconsciously “ashamed” of being immoral. However, they may consciously compensate this and make too much eye contact, another sign they are hiding something. Looking up and to the right has been associated with the brain imagining something, as opposed to down and left which is related to recalling true memories. Lastly, the pupils may dilate from the excitement and nervousness.

When a person lies, they tend to be nervous, stressed and excited. This activates the sympathetic nervous system, colloquially known as the fight or flight mode (rapid blinking is related to this). This causes other signs such as sweating, dry mouth, fast heartbeat and blood pressure. Therefore, a liar may be seen licking or pursing their lips to moisten them. Frequent, loud swallowing is also a clear sign of dry mouth. The face may be slightly flushed as well.

As stated above, the person is also subconsciously ashamed of their lying. This causes the person to face away from the person or look down (think of a child who is lying – their innocence makes signs of deception flare up like Christmas lights). Many people place their hand near their mouth (e.g. rubbing their nose or chin, touching their lips), as if the brain is telling the hands to stop the lie from coming out. They also tend to rub their neck or adjust their collar as touching the neck comforts people. Note that scratching the nose is another sign of lying but not the same as rubbing the nose. Scratching is to relieve the itchiness caused by the raised blood pressure irritating the soft tissue of the nose (Pinocchio effect).

Obviously the facial expression would change also, expressing nervousness and mild stress. This may be concealed with a fake smile (when the “eyes don’t smile”) or anger. It is well-known that people exhibit microexpressions – a flicker of emotion expressed in the face – that only shows for a fraction of a second. Although it is hard to spot, it is a direct display of their true emotion. Fascinatingly, the right face tends to react more as it is controlled by the left brain – responsible for the logical and complex thinking required in telling a lie. This may show as a tic or twitch in the eyes, cheek or mouth.

Moving down the body, a classic sign of deception is the shoulder shrug. Shrugging the shoulders is a message they are “unsure” if what they said is true and is seen (subtly) in many cases of lies. The arms may be crossed (a closed position), which shows they are being defensive (a sign of guilt or discomfort). Similarly, the person may be leaning away from the other person.

The hands are just as important as the face when it comes to lie detection. As mentioned before liars tend to touch various parts of their face and neck while telling a lie. Women tend to rub their hands together or their forearm instead of the neck to comfort themselves. Fidgeting is also very important to notice as this is a comforting act too and exaggerating movements are seen also (reinforcing the “validity” of their lie). Usually, people are aware of this fact and attempt to hide their hands in their pockets, behind their back or behind a bag. They may hold the hands together to prevent fidgeting, or tightly clench their fists. Basically, look for unnecessary (or lack thereof) movements as this almost certainly indicates that something is abnormal.
Similarly, the person may cross their legs (defensive), tuck their feet below the seat (distancing from the other person) or tap their feet (nervousness and excitement).

To finish off, here are some verbal cues for deception. People have a tendency to give short replies when lying. They also talk at a faster pace and higher pitch. These are all due to the subconscious want for the conversation to be over as soon as possible (often accompanied by an awkward or angry attempt at changing the topic). On a similar note, they are more hesitant and less fluent in talking, adding many “umm”s and “uhh”s as they try conjure a lie. Words such as “somebody” “somewhere” “everywhere” that encompass a non-specific or broad target are used to try dilute the details of the lie.

Conversely, the more experienced liar tries to make their lie believable by adding excessive detail to their story. For example, asking a specific detail (that they normally wouldn’t notice) would prompt an answer as opposed to an “I don’t remember”. It is also useful to ask the same question again and check for any inconsistencies.
Lastly, if the more the person affirms that they are telling the truth (e.g. “honestly”, “believe me”, “swear to god”), the more likely they are lying.

This list is not exhaustive and there are many tiny details that can be used to help you decide whether someone is trying to deceive you or not. Again, as the signs are not definitive (e.g. they may be thirsty or just nervous talking to you) it should be considered within the context along with other information. However, it is still an extremely useful tool for finding the truth as everybody lies.

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