Assessment and analysis of testimony in psychology: methods and uses

One of the most important parts of forensic psychology is the one in charge of studying the credibility of the testimony.

We are going to discover how this task is carried out, what are the tools that are used and how the maximum possible reliability is achieved.

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What is the evaluation and analysis of the testimony?

Psychology plays a leading role in the judicial field for many reasons, but one of the most relevant is to be in charge of the evaluation and analysis of the testimony, a fundamental task in many cases in which the witness's own account or The victim of a crime is the only evidence, or one of the few that exists, to be able to reach the truth of the event, so it would be key when making a decision and dictating judgment.

Within forensic psychology, the psychology of testimony would be the branch of this science that would carry out the investigations and develop the methodologies necessary to carry out an analysis of the story that is the most rigorous and reliable, within the possibilities offered by the situation.

The psychology of testimony, therefore, seeks to verify the degree of veracity of a statement on a certain matter. And on many occasions it is not easy to reach a conclusion. Let's stop to take a closer look at two issues that are fundamental in the evaluation and analysis of testimony: accuracy and credibility.

Accuracy of the testimony

The first problem we face is that of evaluating the accuracy of the testimony, and that is that human memory is not everything. reliability that we would like, and in addition there can be very significant differences between the memory capacity of a person and other. Our memory does not work like a video camera in which we press the record or play button, saving and recovering the images as they happened, far from it!

The problems begin at the very moment of living the fact that concerns us, since depending on the capabilities of the person, the attention that is putting, of the stress that is experiencing, and many other variables, the subject will encode the information in his brain in a more or less reliable way and durable.

Later comes the problem of the recovery of memory. Likewise, the characteristics of the person himself and his memory will make it more or less easy to recover the data, but they also enter into I play other factors such as the time elapsed between the event and recovery, and another that is fundamental in this discipline: the suggestibility.

That is why it is tremendously important that the interview be conducted by an expert witness psychologist, to guide and obtain the information always through neutral questions, that do not contaminate the story or do so as little as possible.

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Testimony credibility

But there is another issue that is just as important as accuracy, and that is credibility. Because, what happens if what the subject is telling us, is not that it is not exact, but that it is not even true? There are several situations in which a person can make false testimony.

First of all, he may be lying, plain and simple, because with this he makes a profit, either exonerating himself of some crime or getting him to incriminating another person (or causing them not to incriminate him) makes a profit, or does a person of her surroundings.

Second, it may be that the person has made interpretations of what happened that do not correspond to reality, and therefore is recounting events that did not really happen, or at least not in the way he is recounting them, so his testimony would lack credibility.

By last, the situation may occur that the subject has been suggested, especially if his cognitive abilities are not fully developed, either due to age or having a disability. In these cases, these individuals would be developing a more or less implausible story about events that did not actually occur.

Precisely children and people with intellectual disabilities are two of the groups on which the evaluation and analysis of testimony is studied the most, since they have much more limited tools when it comes to presenting their story and also, as we have already mentioned, they are especially susceptible to suggestibility. This is especially relevant in cases of sexual abuse, since each word during the interview to obtain a quality testimony that allows us to draw conclusions well-founded. Later we will see the technique used for this.

Tools to Evaluate Testimony

We have already seen the relevance of the study of testimony and the need to do it in a rigorous and reliable way, since what is at stake is often a sentence with extremely important legal implications. Therefore, it is necessary to be able to have tools that guarantee that the process is as objective and standardized as possible.

Below we will compare different techniques and tools that can be used and even combined, if necessary, in order to achieve the best possible result and thus offer the judge the most reliable information so that he can dictate sentence in one direction or another, having all the data on table.

1. Psychophysiological techniques

On the one hand there are psychophysiological measurement techniques, the famous polygraph. There is a great popular legend around this technique, so much so that It is popularly called a "lie detector", but you have to be very cautious when using it.. The principle on which it is based is that a person, when lying, tends to show a series of signs physiological that, although imperceptible to the eye, can be measured and verified with the instruments suitable.

In this way, the polygraph would detect changes in a person's heart rate, sweating, breathing, or blood pressure while exposing their testimony, so that the investigator can check these physiological patterns and estimate to what extent they might be compatible with a true statement or a false.

This instrument has many limitations, for which it has received many criticisms in the scientific community. Physiological response patterns can vary greatly between people, and we can obtain false negatives, because the individual is able to control her bodily responses while exposes a lie, but also false positives, by other subjects who, even telling the truth, are too nervous to feel intimidated by being evaluated with this contraption.

2. Behavioral indicators

On the other hand, It is just as important to pay attention to what a person says, as to how they say it, and it is that behavioral indicators can be key when it comes to estimating the quality and veracity of a testimony. This includes both verbal and non-verbal language.

The psychologist has to pay attention to the gesture of the subject, his posture, where he directs his gaze, if he is hesitant at key moments, if he goes around to express an idea ...

The problem with this technique is fundamentally that it requires a lot of practice and experience on the part of the researcher to know how to interpret the response patterns of the subject. In addition, although there are behaviors that are repeated in certain situations and therefore can be extrapolated, there may be large differences between different individuals, and therefore it is important to be cautious and take such behaviors as indicators that increase or decrease the probability of truthfulness, never as an absolute of truth or lie.

3. SVA, assessment of the validity of the claim

The quintessential tool in testimony psychology is the SVA, or Statement Validity Assessment. Is about an evaluation method created to assess the credibility of testimony in cases of alleged sexual abuse of minors.

The key on which the SVA is based is the Undeutsch hypothesis, which maintains that a testimony based on a fact that actually occurred has richness criteria in its content different from those that come from an event made up.

The SVA system is divided into three parts.

• Conducting a semi-structured interview for later transcription.
• Analysis of the interview according to the criteria of the CBCA (content analysis based on criteria).
• Analysis of the validity criteria.

The CBCA is a list with 19 criteria that should be evaluated through the content obtained in the transcript of the interview, checking if they are given and to what extent. The first three are the fundamental ones, and must be given in order to continue carrying out the analysis, or else the testimony is considered incredible. Are these:

• Have a logical structure.
• Have been prepared in an unstructured way.
• Have a sufficient amount of detail.

The rest of the criteria are grouped by categories, referring to the specific contents of the story, its peculiarities, the motivations of the events and finally, the key elements of the act criminal.

Therefore, to this day, 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.

Bibliographic references:

• López, L. (2016). Assessment of the credibility of the testimony through content analysis based on criteria and the measurement of psychophysiological variables. Institutional repository University of Extremadura.
• Arce, R., Fariña, F. (2005). Psychological assessment of the credibility of the testimony, the psychic trace and the simulation: the global evaluation system. Roles of the psychologist.
• Arce, R., Fariña, F., Buela-Casal, G. (2006). Psychology of testimony and cognitive evaluation of the veracity of testimonies and statements. Forensic psychology: Manual of techniques and applications. Madrid. New Library
• Manzanero, A.L., Muñoz, J.M. (2011). The psychological expert test on the credibility of the testimony: Psycho-legal reflections. Madrid. SEPIN.