When we tell a lie our body sometimes reacts in certain ways that does not look right and others pick up on these signs.
Most have heard of the saying "You are a downright liar". This comes from the fact that our eyes dart down to the right when we are untruthful. The reason, verbal language comes from the left side of the brain while body language comes from the right. The right side of the brain is also the creative side. So, the eyes go to the creative side as the person makes up the lie. (That's to your left in case you are wondering).
Another way to tell if someone is lying is if they touch their face, particularly around the nose. This is called the Pinocchio effect which is caused by a chemical released into the mucous membranes when we tell a lie and this chemical creates an itchy sensation around the mouth and nose.
Licking of the lips originates from the same chemical reaction because the chemical dries the lips.
The rate at which we blink our eyes is linked to whether we are experiencing pleasant or unpleasant feelings. Generally, when we are lying we will blink at a faster rate because we are uncomfortable when telling a lie.
When we tell the truth our eyes will generally look straight ahead or they may look upwards as we access the frontal lobe where most of our brain work is conducted.
Folding the arms over the chest when we talk indicates defensiveness, as does placing an item we are holding between the two which acts as a protection ‘barrier’.