In extreme forms of psychosis, the person has difficulty in distinguishing between what’s real and what’s imaginary. This situation raises an interesting philosophical question. Can a person who believes his neighbours are reading his thoughts and poisoning his cat and complains about this to the police be regarded as a liar? This poses a challenge for investigators if they have no understanding of psychosis. It can also make legal proceedings fraught, because the defence could challenge anything the person claims even though some of it may be genuine.
An adult with a learning or mental disability, or a young child, may not be able to tell the difference between the actual facts and what they want the facts to be. Also, as any parent can tell you, a child from a remarkably young age is quite clever at deceiving you if it serves their purpose or they thinks it’s fun. Because of this problem, it’s possible that such individuals may not be allowed to give evidence in court.
Before my grandson was even a year old, he liked to play a game of putting out his hand to me and pretending he was giving me a present, and then pulling his hand away, giggling furiously as I tried to get hold of it. An example of deception being practised from a very early age?
In certain social groups, there’s a deep-seated fear of figures of authority. Therefore, a suspect may agree to having been in a particular place simply because a police officer is telling him that’s the case. This tendency raises issues about more forceful techniques of discovering lying and deceit that I discuss later in this chapter in ‘Interrogating suspects’.
Discovering the difficulties of successful deception
You may be surprised to find that being a successful liar isn’t all that easy. This fact becomes clear when you think about the emotional and intellectual demands that people who are lying place upon themselves:
A liar has to create a lie, requiring imagination.
A liar has to hold the untruth together with the known facts.
A liar has to develop the untruth around plausible possibilities.
A liar has to think through how to make the deception plausible, which can be intellectually challenging.
A liar has to be careful not to give himself away when he’s believed, by some response, such as smirking, that may seem inappropriate to the interviewer.
Sticking fast to the lie is the most difficult aspect of lying. For example, if someone offers you a vast sum of money in exchange for doing nothing, you don’t need any sophisticated lie-detecting equipment to know there’s a catch. You simply know that the world doesn’t work like that, providing free lunches willy-nilly!
Experienced fraudsters know that people may be suspicious of what they’re offering, which is why the fraudster couches his claims in plausible scenarios (such as, ‘Your address came up in a lottery that you didn’t know about’). In the later section ‘Plausibility’ I describe the procedures you can follow for testing the truth and reliability of a statement being given in court.