2. It takes them longer than usual to come up with an answer

When someone’s lying, they are juggling two stories at the same time—what in fact happened and what they want to tell others happened. This thought process takes a lot of brain power, which can lead to long pauses and rambling answers to relatively simple questions.

A liar may add details you didn’t ask for, repeat your question, stammer, pause, or use more filler words like “uh,” “um,” and “ah”.

Research also indicates that people who are telling the truth will often sound more certain, immediate, and involved, and that liars tend to use certain words and language that are open to multiple interpretations.