How we change what others think, feel, believe and do
Thinking and Lying
The detection of lying is something that is of great concern to many people, from police officers interviewing suspects to parents wondering what their children got up to last night. One of the best ways of detecting lies is to spot the way that liars have to think differently.
When a person is telling a lie, they have to make up the story rather than depend on their memory. This requires effort and if they have had no time to prepare, they may bluster and avoid questions until they have thought up their excuse.
When asked about their story, the person who has fabricated will have to recall it. We tend to remember something fabricated as a sequence, rather than the 'random access' of a real memory. This means the person may have to 'play the movie' inside their head, which can make them appear distracted and lead to delays in 'recall'.
Also, when asked to recall the story on separate occasions, the person may not remember the original story they told, particularly in the finer details, and so may be inconsistent over time.
When inconsistencies are pointed out, a truthful person is a bit baffled and immediately accesses memories to try and figure out what really happened. Those who are lying have to replay the story in their heads to the appropriate places and so are slower to respond.
When manufacturing the story, the person will include the main storyline but is unlikely to include the detail of a real experience. When asked for more details they are hence likely to delay again as they dream up new information. it also causes delay when they need to check for internal consistency. If they are not very careful, the larger the story gets, the less likely it is that they will be able to sustain consistency.
Because they have to think about their story, replaying the details and considering what they have already said, there are likely to be various pauses and delays in the response of a liar, as compared to the more spontaneous detail of a truth-teller.
Recalled memory is full of irrelevant detail and a truth-teller will likely include odd details that are not needed but which happened at the same time. The constructed stories of liars are less likely to include this detail and their responses are consequently shorter and simpler.
Another factor that the liar may consider is that the more they say, the more likely they are to make a mistake, so they may well keep their responses short.
In generalizing, liars may also use 'his' and 'her' more than a truth-teller, who will use the names of people in the story more often.
Liars may well use significant manipulative statements, such as adding phrases such as 'to be perfectly honest' and 'the truth is'.
They may try to take control of the interview, for example by asking questions of the interviewer and trying to change the subject of discussion (such as accusing the interviewer of something).
They may also use other control methods such as dressing unusually tidily, bringing along an influential friend, and so on.
Reduced body language
When a person is explaining something that really happened, they live the memory as they explain it with gestures and other body language. When a person is describing something they made up they are likely to be concentrating so hard on getting it right, they may be significantly less animated.
Liars may seek internally to distance themselves from the lie as their ego and super-ego battle over what is right. As a result, they may use less personal pronouns (I, me, mine, etc.).
When liars distance themselves from the person questioning them or otherwise make less emotional connection, they will show signs of limited rapport, which may be seen for example in a lack of matching body language.
When the liar thinks about the possibility of detection, they may well over-compensate, for example in trying to hide signs of lying or increasing signs of rapport and truthfulness.
It is difficult to consciously replicate unconscious actions, for example in compensating for limited body language they may appear over-animated and over-eager in responses.
So watch the person for signs of the above. Also try asking them questions and making comments that would make a liar have to think more.