Lie scales are a type of "truthfulness indicators" that are built into some psychological inventories. These types of scales use utilize redundant questions which are questions that seek to elicit the same information but use varied question formats to check consistency of answers.
For example, "I never regret my actions" and "Sometimes I feel bad about things I've done." These two answers cannot both be answered positive or negative if the subject is being truthful. If the subject's answers are not consistent then it indicates that they are being deceitful. This can be the result of a person trying to present themselves in a more positive light than they really are which is known is research as "faking good."