Detection apprehension, or the fear of being caught lying, is a common emotion felt when lying. When mild, it may actually help the liar avoid mistakes by keeping them alert.
A moderate to strong level of fear can produce behavioral signs producing just what the liar fears- getting them caught! If a liar could estimate how much detection apprehension they would feel if they were to embark on a lie, they could better decide whether it is worth the likely risk.
Even if they already committed, an estimate of how much detection apprehension they are likely to feel could help them to plan countermeasures to reduce or conceal their fear.
A lie catcher could also be helped by this information. They could be alerted to search for signs of fear if they expect a suspect would be very fearful of being caught.