One of the most important parts of forensic psychology is that charged with studying the credibility of testimony..
We will find out how this task is performed, what tools are used and how the maximum possible reliability is achieved.
What is the assessment and analysis of the testimony?
Psychology plays a major role in the judiciary for many reasonsBut one of the most important is to be in charge of the evaluation and analysis of the testimony, a fundamental task in the multitude of casuistry in which the same story of the witness or the victim of a crime is the only proof, or one of the few that there is, to be able to arrive at the truth of success, reason why that would be the key when it comes to making a decision and dictating the sentence.
Within forensic psychology, witness psychology would be the branch of this science that would conduct research and develop the methodologies necessary to conduct the most rigorous and reliable narrative analysis, within the limits of the possibilities offered by the situation. .
Witness psychology therefore seeks to verify the degree of veracity of a statement on a particular subject.. And in many cases, it is not easy to come to a conclusion. Let us stop to take a deeper look at two fundamental questions for the evaluation and analysis of testimony: accuracy and credibility.
Accuracy of testimony
The first problem we face is assessing the accuracy of the testimony, and that is that human memory is not as reliable as we would like, and there can be very significant differences between the ability memory of one person and another. Our memory does not work like a video camera in which we press the record or play button, Backup and recovery of images as you go, much less!
The problems begin at the same time to live the fact which occupies us, since according to the capacities of the person, the attention which is paid, the stress which is lived, and many other variables, the subject which it encodes the information in your brain in a more or less reliable and lasting way.
Then comes the problem of retrieving the recording. Likewise, the characteristics of the person himself and his memory will make data recovery more or less easy, but also other factors come into play such as the time elapsed between the event and the recovery, and another which is fundamental in this discipline. : suggestibility.
This is why it is extremely important that the interview be conducted by an expert witness psychologist., Guide and obtain information always through neutral questions, which do not contaminate the story or make it as minimal as possible.
Credibility of the testimony
But there’s another issue that’s just as important as accuracy, and that’s credibility. Because, what if what the subject tells us is not that it is not correct, but that it is not even true? There are several situations in which a person can give false testimony.
First, you might just be lyingBecause in doing so, he makes a profit, either by exculpating himself from a crime, or by obtaining that person by incriminating another person (or by making him not incriminate him) a profit, or by a person of his entourage .
Second, the person may have made interpretations of what happened that do not correspond to reality, and therefore relate facts that did not really happen, or at least not in the way they relate them, of so that his testimony would have no credibility.
To finish, the situation in which the topic was suggested can be given, Especially if their cognitive abilities are not fully developed, either because of age or because of a disability. In these cases, these people would be developing a more or less improbable account of events that did not actually happen.
Specifically, children and people with intellectual disabilities are two of the groups on which the evaluation and analysis of testimonies are the most studied, because they have much more limited tools to expose their history and also, as we l ‘already mentioned, are particularly sensitive to suggestibility. This is particularly relevant in cases of sexual abuse, as every word must be measured with absolute rigor during the interview to obtain a quality testimony that allows us to draw well-founded conclusions. Later we will see the technique used for this.
Witness assessment tools
We have already seen the relevance of the study of the witness and the need to do so rigorously and reliably, because what is often at stake is a sentence with crucial legal implications. Therefore, it is necessary to have tools available to ensure that the process is as objective and standardized as possible.
Below we will compare different techniques and tools that can be used and even combine them, if necessary, to achieve the best possible result and thus offer the judge the most reliable information so that he can rule one way or another. ., Have all the data. on the table.
1. Psychophysiological techniques
On the one hand, there are the techniques of psychophysiological measurements, the famous polygraph. There is a great popular legend around this technique, to such an extent it is commonly called the “lie detector”, but you have to be very careful in its use. The principle on which it is based is that a person, by lying, tends to show a series of physiological signals which, although imperceptible to the eye, can be measured and verified with the appropriate instrumentation.
In this way, the polygraph would detect changes in a person’s heart rate, sweating, breathing, or blood pressure while exhibiting their testimony, so that the researcher could check these physiological patterns and estimate how well they might. be consistent with a true or false statement.
This instrument has many limitationsIt has therefore received a lot of criticism from the scientific community. Physiological response patterns can vary widely between people, and we can get false negatives, so that the individual is able to control their bodily responses while exposing a lie, but also false positives, by other subjects. who, while telling the truth, are too nervous to feel intimidated about being evaluated with this artifact.
2. Behavioral indicators
On another side, it is as important to pay attention to what a person says as it is to how they say it, And can behavioral indicators be essential in estimating the quality and veracity of a witness. This includes both verbal and non-verbal language.
The psychologist must pay attention to the subject’s gesture, his posture, where he directs his gaze, If you hesitate at key moments, if you turn around to express an idea …
The problem with this technique is that it requires a lot of practice and experience on the part of the researcher to know how to interpret the subject’s response patterns. In addition, although there are behaviors that are repeated in certain situations and which can therefore be extrapolated, there can be large differences between different individuals, and it is therefore important to be careful and to view these behaviors as indicators that increase or decrease the likelihood of. veracity, never as an absolute truth or lie.
3. SVA, assessment of the validity of the declaration
The tool par excellence in witness psychology is the SVA, or Statement Validity Assessment. It is an assessment method created to assess the credibility of testimony in cases of allegations of child sexual abuse.
The key on which the SVA is based is the Undeutsch hypothesis, which holds that a testimony based on a true fact has different criteria of richness in its content than those which come from an invented fact.
The SVA system is divided into three parts.
- Realization of a semi-structured interview for later transcription.
- Analysis of interviews according to CBCA criteria (content analysis based on Criteria).
- Analysis of validity criteria.
The CBCA is a list of 19 criteria that should be assessed through the content obtained in the interview transcript, checking whether they are given and to what extent. The first three are the fundamentals, and they must be given in order to continue doing the analysis, otherwise the testimony is given as incredible. These are:
- Have a logical structure.
- Have been developed in an unstructured way.
- Have enough detail.
The other criteria are grouped by categories, referring to the specific content of the story, its peculiarities, the motivations of the facts and finally, the key elements of the criminal act.
So today the tool that offers the most guarantees in the evaluation and analysis of testimony is the CBCA, Within the SVA system, although we have already seen that it is used for a very specific casuistry.
- Lopez, L. (2016). Assessment of the credibility of the testimony through content analysis based on criteria and the measurement of psychophysiological variables. Institutional directory University of Extremadura.
- Maple, R., Flour, F. (2005). Psychological expertise of the credibility of testimony, psychic imprint and simulation: the global evaluation system. Articles by the psychologist.
- Arce, R., Fariña, F., Buela-Casal, G. (2006). Psychology of witnesses and cognitive assessment of the veracity of testimonies and statements. Forensic Psychology: Manual of Techniques and Applications. Madrid. New library
- Manzanero, A EL, Muñoz, JM (2011). The psychological expert test on the credibility of testimony: Psycho-legal reflections. Madrid. Sepin.