Is the testimony of witnesses and victims of a crime reliable?

In certain countries, such as the United States, the law dictates that the testimony of the victim or a witness is comparable to the weapon of the crime as evidenceto. But, Are witnesses' memories an objective and reliable enough clue to solving a case?

The weapon is a physical and tangible evidence from which very useful information can be obtained: who was its owner or who had wielded it by the prints on it. But the memory of the human being is not something objective and immutable. It does not work like a camera, as various investigations in psychology have shown. In fact, the psychologist Elisabeth loftus proved throughout the 20th century that it is even possible to create autobiographical false memories within people's minds.

Creating false memories

Almost all of our personal memories are modified, disturbed by experience and learning. Our memory does not produce a fixed and detailed memory of an event, on the contrary we only usually remember something that we could call “the essence”. By remembering only the basics, we are able to relate memories to new situations that bear some resemblance to the original circumstances that prompted the memory.

In this way, the memory operation It is one of the pillars that make learning possible, but also one of the causes of the vulnerability of our memories. Our memory is not perfect, and as we have seen many times without being surprised; it is fallible.

Long-term memory and memory retrieval

It should be noted that our memories are stored in what we call the long term memory. Every time we reveal a memory in our daily life, what we are doing is building the memories with pieces that we “bring” from there. The passage of memories from long-term memory to the operating and conscious system is called recovery, and it has a cost: every time we remember something and then take it back to the warehouse long term, memory is slightly altered when mixed with present experience and all its conditioning factors.

Moreover, people do not remember, we rework, we build again the facts every time we we verbalize, always in different ways, always generating different versions of it event. For example, recalling an anecdote among friends can provoke a debate about what clothes one was wearing that day or what exactly when he arrived home, details that may end up being modified when we bring the memory back to the Present. Details that we do not pay attention to because they are not usually significant, but that are key in a trial.

The effect of emotions on memory

Situations of emotional stress they also have a very powerful effect on the memory of witnesses and especially on the memory of victims. In these situations the impact produces more or less permanent damage to memory. The consequences are in the tremendously vivid memory of small details and a deep void about actions and circumstances that may be more important.

Peripheral memories are more likely than central memories when faced with an event with great emotional impact. But, especially, emotions bathe and drench memories with subjectivity. Emotions cause what has hurt us to seem much more negative, perverse, ugly, obscene or macabre than it is objectively; and in return that associated with a positive feeling for us seems more beautiful and ideal. For example, curiously, nobody hates the first song he heard with his partner, even if it was played on the radio or in a disco, because it has been associated with the feeling of love. But we must not lose sight of the fact that for better or for worse, objectivity in a trial is of prime necessity.

A shocking damage, such as a rape or a terrorist attack, can create in a victim the condition of posttraumatic stress, provoke intrusive memories in the victim and also blocks that incapacitate him to recover the memory of it. And pressure from a prosecutor or a police officer can create memories or testimonies that are not true. Imagine that a paternalistic police officer tells you something like "I know it's hard, but you can do it, if you don't confirm it to us that man will go home free and satisfied." An insidious police officer or prosecutor, pushing too hard for answers, will bring up a false memory. Only when the victim is able to emotionally distance himself from the event and downplay it, will she (perhaps) be able to regain the memory.

To trust the memories ...

One technique to avoid post-traumatic stress and blockage is to elaborate or tell someone the facts as soon as they happen. Externalizing the memory in a narrative way helps to make sense of it.

When it comes to witnesses, there are always memories more credible than others. It never hurts a forensic expert to assess the value of the memory before allowing to testify in a trial. The optimal level to which we remember is given when our physiological activation is medium; not so high that we are in a state of anxiety and stress as can occur in an exam; not so low that we are in a state of relaxation that borders on sleep. In such a case, a crime causes a high physiological activation, an emotional stress that is associated with event and that therefore arises every time we try to remember, decreasing the quality of the I remember.

Therefore, the memory of a witness will always be more useful than that of the victim as it is subject to less emotional activation. It should be noted, as a curiosity, that the most credible memory of a victim is the one that focuses on the object of the violence, that is, on the weapon.

Bias in judicial processes

On the other hand, we must bear in mind that, sometimes, recognition wheels and interrogations can be unintentionally biased. It is due to that bias towards injustice, or due to ignorance of the effect of asking a question in a certain way or ordering a set of photographs in a specific way. We cannot forget that policemen are human beings and they feel an aversion towards crime as great as that of the victim, so their objective is to put the culprit behind bars as soon as possible; They biasedly think that if the victim or witness says that one of the suspects looks like the culprit, it must be him and they cannot release him.

There is also this bias in the population that dictates that “if someone is a suspect, they will have done something”, so that there is a general tendency to believe that suspects and accused are blindly guilty. For this reason, when faced with a series of photographs, witnesses often tend to think that if they are presented with these subjects it is because one of them must be the culprit, when sometimes These are random individuals and one or two people who slightly coincide in certain characteristics with those that have been described to them (which in fact do not even have to be truthful). This mix of biases from the police, the prosecutor, the judge, the jury, the witnesses, and the public can result in a combination such that an innocent person is found guilty, a reality that happens occasionally.

Of course I do not mean that any testimony should not be valued, but it must always be done by evaluating its veracity and reliability. It must be borne in mind that the human mind is frequently wrong and that we must emotionally distance ourselves from suspects before trying them to do so objectively, attending not only to reliable witnesses, but also to evidence rigorous.