There isn’t a scientifically reliable two-question trick that can prove someone is lying. People can contradict themselves because they’re nervous, confused, mistaken, or remembering events imperfectly—not necessarily because they’re deceptive.
If your goal is to spot inconsistencies without assuming guilt, two useful questions are:
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“Can you walk me through exactly what happened, from the beginning?”
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“What details are you least certain about, and what could help verify them?”
Then pay attention to whether the account remains broadly consistent when the person explains it again. More useful than body-language “tells” are specific, independently verifiable details, changes in the story, and evidence from reliable sources.
A useful caution
Techniques such as asking someone to tell a story backward, watching their eye movements, or interpreting nervousness as deception are often presented online as lie detectors, but they aren’t reliable ways to determine whether someone is lying.
If you’re dealing with an important accusation or conflict, separate “their story has inconsistencies” from “therefore they’re lying.” The first can be observed; the second requires stronger evidence.
