Polygraph tests- so-called "lie detectors"--are typically based on detecting autonomic reactions and are considered unreliable (see "The polygraph in doubt"). That's why psychologists have been cataloging clues to deception--such as facial expressions, body language and linguistics--to help hook the dishonest.
Study the eyes
Researchers say no. Science shows that liars do not avoid eye contact any more frequently than those telling the truth. The key thing to look for in eye movement is deviation from their baseline.
Many NLP practitioners claim that a person's eye-movements can reveal a useful insight into whether they are lying or telling the truth. According to this notion, looking up to the right is indicative of lying whereas looking up to their left suggests that they are telling the truth.
However, it is also thought that looking to the right and downwards suggests self-doubt, while looking to the right and up indicates that a person is telling untruths.
Eye Direction
Looking to their left indicates that they're reminiscing or trying to remember something. On the other hand, looking to their right indicates more creative thoughts, and this is often interpreted as a potential sign that someone may be being deceitful in some situations, i.e. creating a version of events.
In line with this assumption, previous studies have shown that lying is associated with greater pupil dilation, a behavioral cue that typically manifests itself under conditions of stress or cognitive effort. In accordance with these results, we predicted greater pupil dilation when lying than when telling the truth.
Look for flared nostrils, lip biting, rapid blinking or sweating. These changes in facial activity signify an increase in brain activity as a lie begins. Some people will get a slight flush to their face when they are lying, so look for blushed cheeks as anxiety may set in.
Liars often try to determine what you might know already, so using open-ended questions forces them to recount details that didn't happen. When asking open-ended questions, never use the word “why” which implies that they did it. Instead, replace it with “what”, which is more distancing.
One of the most common ways people discover they've been lied to is from third-party information. Deception done for the right reasons is not really deception. What is meant by the phrase "deception can serve as a social lubricant?" -People commonly engage in deception to get what they want from other people.
Your therapist can't read your mind, so they may not always know for certain when you lie. That said, plenty of cues in your speech and body language can alert your therapist to dishonesty. They might notice things like unnecessary or embellished details, or changes in your story from session to session.
The first attempt to use a scientific instrument to detect deception occurred around 1895, when Lombroso applied a blood pressure instrument (hydrosphygmograph) to criminal suspects.
Small pupils can be due to bright light, an emotional response, or looking at something far away. There are six health risks that can cause pinpoint pupils, or miosis. These include substance abuse, prescription drugs, environmental toxins, diseases, Horner syndrome, and trauma to the eye or brain.
Pupils are supposed to dilate under normal circumstances due to light changes and emotional variables. Most of the time, dilated pupils will go back to normal size on their own. If pupils dilate suddenly, occur after a traumatic injury or cause headaches and confusion, seek medical attention immediately.
Eye contact has long been central to human interactions. Changes in emotion might cause pupil dilation. The autonomic nervous system triggers various involuntary responses during emotions, such as fear or arousal. Some research suggests that pupil dilation is one of these involuntary responses to arousal or attraction.
Individuals usually look away when they are thinking, hesitating, or talking in a non-fluent way. This behavior likely serves two purposes, the first of which is to shield themselves psychologically from the embarrassment of being judged for not proceeding.
Making Eye Contact
If she looks at you and then instantly turns away, it may be because she is shy or doesn't want to get caught looking at you. If she looks back at you and smiles, that's an invitation for you to go introduce yourself.
Looking Downwards
If someone looks down at the floor a lot, they are probably shy or timid. People also tend to look down when they are upset, or trying to hide something emotional. People are often thinking and feeling unpleasant emotions when they are in the process of staring at the ground.
What is the one thing all liars have in common? Liars avoid confronting facts and tend to hide their feelings. Most liars also tend to be insecure, manipulative, or distrustful.