How we change what others think, feel, believe and do
How do you stop a person from telling lies? Whilst it is not always possible to do this, there are a number of ways you can help keep the person on the straight and narrow way.
Fear is applicable in two ways when encouraging truth. If a person is to tell the truth, then they should not be fearful in a way that would encourage lying in any way. This may be connected with the setting in which they are questioned, the way you question them and the general trust they have in you.
Fear is applicable if they are thinking of lying, where they should be fearful of being caught out. You can encourage this with how you talk with them. Be careful, however, of making them fearful of you and so becoming so stressed they are unwilling to say anything of substance. They should be afraid of not telling the truth far more than being afraid of the consequences of telling the truth.
Although fear of consequences can be effective, fear of punishment for lying is a terrible way to teach children to tell the truth. Studies of this have shown that it just makes them better liars.
When there are other people present, a liar knows that these may act later as witnesses, making it more difficult to deny they said something. Just having a witness present is often enough to keep the person truthful. The witness may also engage in the discussion, asking questions and pointing out inconsistencies.
Just one witness makes a difference. There can actually be a problem with multiple witnesses in a legal setting as the defending lawyer can often show that memories differ in critical detail.
When you ask for details, you make it harder for liars, who have to make new things up. They also have to put effort into checking that what they say is consistent with what they have said before. You can often see this in pauses and concentration where things should be relatively easy for them to remember.
If you tell the person beforehand that you are going to be asking for detail and also going back over various points, they may conclude that it is simpler just to tell the unvarnished truth from the beginning.
It has been found that when people are reminded of their values, for example when they have recently discussed something of moral importance and where they have had to assert their values, then they are likely to be more honest in subsequent discussions.
An approach used in interviews is to ask the person first 'Would you say you are an honest person?' This is something of a double bind as they have to say 'yes'. Having been reminded and then having asserted their honesty, then in order to sustain internal consistency, they have to be honest in the other things they say.
Police in many countries record all interviews with suspects. This not only helps keep the police from using leading statements and other suspect methods -- it also puts pressures on the suspects to tell the truth.
Whilst electronic recording in ordinary conversation can be problematic, records can be made from what the person says and most will be aware of the permanence of such statements. For example many organizations keep minutes of meetings.
People are also more reluctant to lie in emails, which makes asking 'Could you email me the details?' a powerful way of encouraging truth.
So in order to encourage truth-telling, use the above methods to create the conditions.