#6 Ask them to tell their story in reverse

According to some studies, asking people to tell their stories in reverse instead of chronological order can enhance the precision of lie detection. As cognitive load rises, it may become easier to recognize verbal and nonverbal clues that differentiate between lying and telling the truth.

In addition to being more cognitively demanding, lying also requires a lot more mental effort on the part of the liar as they constantly watch their actions and evaluate how others are reacting. Being believed by others is important to them, as does maintaining their credibility.

All of this requires a lot of work, so if you add a challenging task (like telling their story backwards), it might be easier to notice narrative flaws and other behavioral red flags.