I like to think this is quite intuitive. If you have enough conversations with people in your life, over time you should be able to tell if someone is being deceitful just from the way they act.
Ways I can tell include:
- Eye contact – when someone is being evasive with their eye contact it’s usually a sign that they’re not being wholly truthful.
- Facial expressions – someone lying often has exaggerated facial expressions, as if to over compensate, or sometimes a forced and deliberate suspension of normal expression, as if to hide tell-tale signs.
- Body composure – the way someone sits/stands is a giveaway. If they have their arms crossed, are fidgeting (e.g. shaking a leg, moving their weight from each leg frequently, touching their face and hair) or facing their body away from you, as if deflecting the conversation, it could be a sign they’re lying.
- Speech patterns – liars have to remember their lies, which can cause problems with coherent speech e.g. they may stutter, pause too much or their voice may quiver.
- Their use of language – someone lying may use more defensive words or be aggressive with their language. A notable example could be flattery. Over using compliments may be a sign they’re also trying to manipulate you or deflect the conversation as they see it as interrogation.
- Nervous system responses – for most people lying induces CNS responses, such as blushing, sweating or shaking.