Evaluation and analysis of testimony in psychology: methods and uses.

An overview of the evaluation and analysis of testimony in forensic psychology.

One of the most important parts of forensic psychology is the study of the credibility of testimony..

We will discover how this task is performed, what tools are used and how to achieve the highest possible reliability.

What does the evaluation and analysis of testimony consist of?

The psychology has a great protagonism in the judicial scope for many reasons.However, 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 account of the witness or victim of a crime is the only evidence, or one of the few that there is, to reach the truth of the event, so it would be key when making a decision and sentencing.

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

The psychology of testimony, therefore, aims to verify the degree of veracity of a statement on a given subject.. And on many occasions it is not easy to reach a conclusion. Let us pause to look in depth at two issues that are fundamental in the evaluation and analysis of testimony: accuracy and credibility.

Accuracy of testimony

The first problem we face is that of assessing the accuracy of the testimony, because human memory is not as reliable as we would like it to be, and there can be significant differences between the memory capacity of one person and another. Our memory does not work like a video camera in which we press the record or play button, saving and retrieving the images.and then saving and retrieving the images as they have occurred - far from it!

The problems begin at the very moment of experiencing the event in question, since depending on the person's capacities, the attention he/she is paying, the stress he/she is experiencing, and many other variables, the subject will encode the information in his/her brain in a more or less reliable and lasting way.

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

That is why it is tremendously important that the interview is conducted by an expert psychologist in testimony.It is therefore extremely important that the interview is conducted by a psychologist expert in testimony, to guide and obtain the information always through neutral questions, which do not contaminate the story or do so as little as possible.

Credibility of testimony

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 only inaccurate, but not even true? There are several situations in which a person may give false testimony.

In the first place, he may be lying, plainly and simply, because he is making a profit.In the first place, he may be lying, simply and plainly, because he is getting a benefit from it, either to exonerate himself of a crime or to achieve a profit by incriminating another person (or by not incriminating him), or a person around him.

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

Finally, it is possible that the subject may have been suggestible, especially if his or her cognitive abilities have been impaired.especially if their cognitive abilities are not fully developed, either because of age or disability. In these cases, such individuals would be elaborating a more or less implausible account of events that did not actually occur.

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

Tools to evaluate the testimony

We have already seen the importance of studying the testimony and the need to do it in a rigorous and reliable way, since the stakes are often very high. what is at stake is often a sentence with legal implications of tremendous importance.. Therefore, it is necessary to be able to count on 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 pass sentence in one direction or another, having all the data on the table.

Psychophysiological techniques

On the one hand, there are the psychophysiological measurement techniques, the famous polygraph. There is a great popular legend surrounding this technique, so much so that it is popularly called the "polygraph detector". popularly called "lie detector", but we must be very cautious in its use.. The principle on which it is based is that a person, when lying, tends to show a series of physiological signals that, although imperceptible to the eye, can be measured and checked with the appropriate instruments.

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

This instrument has many limitationsIt has been widely criticized in the scientific community. The physiological response patterns can vary greatly between individuals, and we can obtain false negatives, because the individual is able to control his bodily responses while exposing a lie, but also false positives, by other subjects who, even telling the truth, are too nervous because they feel intimidated by being evaluated with this device.

2. Behavioral indicators

On the other hand, it is as important to pay attention to what a person says as to how he says it.Behavioral indicators can be key in estimating the quality and veracity of a testimony. This includes both verbal and nonverbal language.

The psychologist must pay attention to the subject's gestures, posture, where he/she is looking, whether he/she is hesitant, if he/she is hesitant or not.whether he/she is hesitant at key moments, whether he/she takes detours 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. Furthermore, 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 these behaviors as indicators that increase or decrease the probability of truthfulness, never as an absolute of truth or falsehood.

3. SVA, assessment of statement validity

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

The key on which the VAS is based is Undeutsch's hypothesis, which maintains that a testimony based on a real event has different criteria of richness in its content than those that come from an invented event.

The VAS system is divided into three parts.

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

The CBCA is a list of 19 criteria to be evaluated through the content should be evaluated through the content obtained in the transcription of the interview, checking whether and to what extent they are present.. The first three are the fundamental ones, and must be given to be able to continue performing the analysis, or else the testimony is given as unbelievable. They are these:

• To have a logical structure.
• To have been elaborated 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 facts and finally, the key elements of the criminal act.

Therefore, to date, the tool that offers most guarantees in the evaluation and analysis of the testimony is the CBCA, within the SVA system, although we have already seen that it is used for a very specific casuistry.

Bibliographical references:

• López, L. (2016). Evaluation of the credibility of testimony through criteria-based content analysis and the measurement of psychophysiological variables. Institutional repository University of Extremadura.
• Arce, R., Fariña, F. (2005). Psychological assessment of the credibility of testimony, psychic imprint and simulation: the global evaluation system. Papers of the psychologist.
• Arce, R., Fariña, F., Buela-Casal, G. (2006). Psychology of testimony and cognitive assessment of the veracity of testimony and statements. Forensic psychology: Manual of techniques and applications. Madrid. Biblioteca Nueva.
• Manzanero, A.L., Muñoz, J.M.. (2011). La prueba pericial psicológica sobre la credibilidad del testimonio: Reflexiones psico-legales. Madrid. SEPIN.