There is this myth that you can tell if a person is lying by only looking them straight in the eye when they talk. Well, liars have become smart and now lie with an intense gaze and a straight face without blinking. If you try this method then you are going to be lied to and you would be none the wiser.
There is also the "lie detector" method that is widely claimed to detect when someone is lying. Liars have also learned how to beat the lie detector which is why lie detector results are no longer admissible as evidence in courts.
However, you can estimate the probability of a statement being a lie or the truth based on some factors.
The following YES/NO questions should help you tell if a person is lying or telling the truth.
1. Does the source stand to gain if you believe the statement?
Remember that people are highly likely to lie if the lie they tell will favor them in some way. Just ask yourself what will the source of the information gain if you believe the statement. A good example is a salesman, who says anything to get you to buy their product, or a politician who promises you(the voter) anything to get you to vote for them.