In many criminal cases, the prosecution uses witness statements that incriminate a defendant. For a lawyer, this is often a reason to question the witness in question. If the lying witness can be unmasked or if the statement proves to be unreliable, sometimes the supporting evidence under a criminal case can be knocked out resulting, for example, in an acquittal.

While it is not always easy to overturn witness evidence, there are options. Judges are aware that there are lying witnesses, but also that the statements of honest and sincere witnesses, may nevertheless be unreliable. For example, because their memories are coloured in one way or another, so their possible observations cannot be precisely established. To properly value witness statements, courts themselves have sought the help of (neuro)psychologists, leading to suggestions and recommendations made in July this year public have been made.

The basic premise is that you cannot tell a witness see Whether he is lying. 'Looking to one side, squirming nervously, looking away, stuttering, talking fast, dropping long silences - it doesn't have to indicate lying. It could be a reaction to stress, or just belong to the person. Nor does a facial expression give accurate information. After all, that is easy to manipulate.'

However, it can be assumed that lying takes more effort than telling the truth. A liar often watches the interlocutor, looking for signs that his story is believed. Furthermore, he sometimes has to think carefully about exactly what he has told to whom and prefers to stay away from verifiable details. After all, these could expose him. Sometimes a witness is easily caught in a lie after being asked about verifiable details such as the weather or a location. Even an unexpected question, such as a request to put the story backwards, can put a lying witness through the roof.

But even an honest and sincere witness can incorrectly recall them memories. Even if he is so convinced that his memories are correct. Stubbornness says more about the character of the witness himself than about his testimony. That has to do with how human memory works, which is not made to, as if it were a computer, storing events permanently and truthfully. A memory can undergo constant changes due to the neuroplasticity of the brain. An experience can also be coloured by the significance of that experience in a person's life. If a witness was on his way to a job interview, for example, and wanted to arrive on time, this may affect the memory in a different way than a witness who happened to be walking the dog at that moment.

This can involve all kinds of biases. For example, people often attach more value to information that corresponds to their existing conceptions and more quickly discard information that does not correspond to these conceptions. People are also more likely to think of vivid, emotional information. This is why more people fear sharks while more people die from ingesting cleaning products. Example is the so-called weapon focus. When people see a gun, they will usually pay less attention to what else is going on around them.

There may also be of collaborative storytelling, where memory is affected by outside information, such as seeing pictures, reading media reports, suggestive questions or comments from others. Differences in interpretation about a conversation, for example, can also lead to misses.

The lawyer who wants to undermine an incriminating testimony about his client would do well to take into account the workings of human memory when preparing for the interrogation. The recommendations adopted by the courts of appeal on this point may serve the legal profession well in this regard.

 Mr D.M Penn