Can we trust the testimony of witnesses and victims of a crime?
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 crime as provento . But, Are the memories of witnesses a key objective and reliable enough to solve a case?
The weapon is a physical and tangible proof from which very useful information can be obtained: who was its owner or who had taken it by footprints 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, psychologist Elisabeth Loftus proved throughout the 20th century that it is even possible to create false autobiographical memories inside the minds of people.
Creating false memories
Almost all of our personal memories are modified, disturbed by experience and learning . Our memory does not elaborate a fixed and detailed memory of a fact, on the contrary we only remember something that we could call "the essence". By remembering only the basics we are able to relate the memories to new situations that bear some resemblance to the original circumstances that aroused the memory.
In this way, the functioning of memory 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 often seen without surprise; It is fallible.
Long-term memory and recovery of memories
It should be noted that our memories are stored in what we call the long-term memory. Every time we show a memory in our daily life, what we are doing is to build memories with pieces that we "bring" from there. The passage of memories from long-term memory to the operating system and conscious is called recovery, and has a cost: every time we remember something and then we take it back to the long-term warehouse, the memory is slightly altered by mixing with present experience and all its conditioning factors.
What's more, people do not remember, we re-elaborate, we build facts again every time we verbalize them, always in different ways, always generating different versions of the same event. For example, remembering an anecdote among friends can provoke a debate about the clothes one wore that day or at what time exactly it arrived at home, details that can end up being modified when we bring back the memory to the present. Details to which we do not pay attention because they are not usually significant, but which are key in a trial.
The effect of emotions on memory
Situations of emotional stress also have a very powerful effect on the memory of the witnesses and especially on the memory of the victims. In these situations, the impact produces more or less permanent damage to the memory. The consequences are in the tremendously vivid memory of small details and a deep emptiness about actions and circumstances that may be more important.
Peripheral memories are more likely than central ones to an event with great emotional impact . But, in particular, emotions bathe and soak memories of subjectivity. Emotions cause that what has hurt us may seem much more negative, perverse, ugly, obscene or macabre than it is objectively; and in contrast, that associated with a positive feeling for us seems more beautiful and ideal. For example, curiously, no one hates the first song he heard with his partner, even if it played on the radio or in a nightclub, 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 essential.
A shocking damage, such as a rape or a terrorist attack, can create a post-traumatic stress condition in a victim, provoke intrusive memories in the victim and also blockages that make it incapable of recovering the memory. And the pressure of a prosecutor or a policeman can create memories or testimonies that are not true. Imagine that a paternalistic police cop tells you something like "I know it's hard, but you can do it, if you do not confirm it, that man will go home free and satisfied". A policeman or an insidious prosecutor, who presses too hard to get answers, will make a false memory emerge. Only when the victim is able to distance himself emotionally from the fact and downplay it, will he be able (perhaps) to recover the memory.
To trust memories ...
A technique to avoid post-traumatic stress and blockage is to elaborate or tell someone the facts as soon as they have happened. Externalizing the memory in a narrative way helps make sense .
When it comes to witnesses, there are always more credible memories than others. A forensic expert who assesses the value of the memory before allowing testifying in a trial never hurts. The optimal level we remember is when our physiological activation is medium; not so high that we are in a state of anxiety and stress as can be given in an exam; not so low that we are in a state of relaxation that rubs the dream. In such a case a crime causes a high physiological activation, an emotional stress that is associated to the event and that therefore arises every time we try to remember, decreasing the quality of the memory.
So, 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 one that focuses on the object of violence, that is, on the weapon.
The bias in judicial processes
On the other hand we must bear in mind that, sometimes, the reconnaissance wheels and interrogations may be unintentionally biased . It is due to this bias that exists towards injustice, or due to ignorance of the effect of formulating a question in a certain way or ordering in a specific way a set of photographs. We can not forget that the police are human beings and feel an aversion towards crime as great as that of the victim, so their goal is to get the guilty as soon as possible behind bars; They think skeptically that if the victim or the witness says that one of the suspects looks like the guilty party, it is because he must be and they can not let him go.
There is also that bias in the population that says that "if someone is suspicious, something will have done", so that there is a widespread tendency to believe that suspects and defendants are blindly guilty . For this reason, in front of a series of photographs, witnesses often tend to think that if they are presented to those subjects it is because one of them must be the guilty party, when sometimes they are random individuals and one or two people who coincide slightly in certain characteristics with which they have been described (which in fact do not even have to be true). This mixture of biases from the police, the prosecutor, the judge, the jury, the witnesses and the population can result in a combination such that an innocent is found guilty, a reality that happens occasionally.
Of course I do not want to say that any testimony should not be evaluated, but it must always be done evaluating its veracity and reliability. Keep in mind that the human mind is often wrong and that we must distance ourselves emotionally from the suspects before judging them to do so objectively, attending not only to reliable witnesses, but also to rigorous tests.