Truthfulness bias: what it is and how it affects our perception.

A psychological phenomenon that affects our perception and its relationship to truth.

Have you ever heard of truthfulness bias? It is a phenomenon with two possible meanings: on the one hand, it is the tendency to believe that others are honest and therefore tell the truth, and on the other hand, it is the tendency to remember "false" information as true.

In this article we bring you the findings of scientific research for each of these two meanings, since the phenomenon of truthfulness bias has been studied in both ways. As we will see, it is a concept closely related to criminal investigation and legal psychology. But why? Let's find out.

Truthfulness bias: two meanings

First of all, we should bear in mind that the truthfulness bias has two possible meanings.

Meaning 1: Believing others to be honest

The first meaning of the truthfulness bias, a term introduced by Zuckerman et al. in 1981, is defined as the tendency we have to believe or assume that others are honest. the tendency we have to believe or assume that other people are honest (and tell the truth, that they tell the truth). (and that they tell the truth, that they are sincere).

That is, according to the truthfulness bias, we would assume that others are honest much more than they actually are.

2. Meaning 2: Remembering "false" information as true

The second meaning of the truthfulness bias, which has been recently investigated in a study by Pantazi, Klein & Kissine (2020), refers to the fact that people tend to erroneously recall as true information that has been explicitly explained to us as false.

That is, according to this bias, we tend to remember as true information labeled as "false". Sounds a bit contradictory, doesn't it?

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Scientific research on both phenomena

But what exactly does scientific research say about truthfulness bias? Let's analyze the research that has been done on this phenomenon, differentiating the two meanings attributed to it.

1. Truthfulness bias 1: believing others to be honest

What does the research suggest when analyzing the truthfulness bias, understood as the "excessive" belief in the honesty of others? Are we good at detecting lies?

According to a study by Levine, Park and McCornack (1999), we tend to identify truths more easily than lies..

But why is that? According to the authors, precisely because we manifest this truthfulness bias, and tend to consider that others generally tell us the truth, this would explain why our accuracy in judging truths is good, and in judging lies is a bit poorer (Levine et al., 1999; Masip et al., 2002b).

In subsequent studies, specifically in a meta-analysis by Bond and DePaulo, the mean % of truth judgments was found to be 55% (by chance, this % is expected to be 50%, i.e. the mean was rising). This % made the judges' accuracy in judging statements as true as high as 60%. This last percentage was slightly higher than when judges had to judge false statements (which stood at 48%). (which stood at 48.7%).

Police

We have talked about judges, but what about police officers? According to research by Meissner and Kassin (2002), Bond and DePaulo (2006) and Garrido et al. (2009), in police officers this tendency that we have explained is reversed, and it is observed that in most cases the accuracy for detecting false statements is higher than the accuracy for detecting true statements.

The mendacity bias

One possible explanation for this is that police officers have a greater tendency to make judgments of untruth rather than truth; in other words, they show the mendacity bias.How is this bias defined? It consists of the tendency to make more mendacity judgments than truthful ones (which is true for police officers).

In non-professionals (i.e., neither judges nor police nor those belonging to the legal sector), on the other hand, this bias does not appear, since according to research (Levine, Park and McCornack, 1999) we would tend to be more accurate in judging truth than lies (i.e., the mendacity bias is reversed).

2. Truthfulness bias 2: remembering "false" information as true

Studies prior to that of Pantazi et al. (2020), already mentioned, reveal that people are inherently truth-biased, i.e., we tend to remember "false" information as true.This means that we tend to believe information we receive, even when it is marked or labeled as false information.

According to the study by Pantazi et al. (2020), the truthfulness bias consists of a kind of inefficiency that we present when it comes to gauging the quality of the information provided to us by the media, which also affects when it comes to "correcting" such information.

Development of the Pantazi et al. study (2020)

To demonstrate veracity bias, the experimenters of the study we discuss proceeded as follows: they designed an experimental paradigm where mock jurors (condition or study 1) and professional jurors (condition or study 2) were asked to read two crime reports..

These reports contained aggravating or mitigating information for such crimes, and it was explicitly specified that this information was false.

What they evaluated in the study was: the decisions made by the jurors in relation to the cases presented (i.e., the sentences) including how the false information influenced them, as well as their memory (and, evidently, also how (and, evidently, also how false information affected it).

In short, the aim was to check whether the truthfulness bias appeared in these groups, in the legal context in which the aforementioned study is framed.

Findings

What do the findings of this experiment suggest about truthfulness bias?

Basically, that both the mock jurors and the professional jurors exhibited truthfulness bias; that is, all participants had made case decisions biased by false information.This means that all participants had made case decisions biased by false information, and that their memory was also biased by false information.

Specifically, the results of condition or study 2 (professional jury) indicated that professional judges had been affected (or influenced) by false information in reaching their verdicts, similar to study 1 (mock jury). That is, to a similar degree.

On the other hand, it is also true that there was considerable variability in the judges' decisions, once they had heard the false information, in relation to the years of imprisonment they proposed for the defendants (across the different cases).

In addition, the results of the study reveal that 83% of the time, judges issued longer sentences after having received false information or evidence that aggravated the crimethan when they received false evidence (and not so much information).

Memory

What did you observe in the judges in terms of the memory evaluated? The results show how jurors, both mock and professional, showed a tendency to misremember aggravating and explicitly false information..

A curious fact revealed by the study is that the ability of judges to filter or discriminate false information from false information (whether we analyze their decisions and judgments, or their memory), did not depend on their years of experience.

Bibliographical references:

Garrido, E., Masip, J. and Alonso, H. (2009). The ability of police officers to detect lies. Revista de derecho penal y criminología, 3 (2), pp. 159-196. Levine, T. R., Park, H.. S., & McCornack, S. A. (1999). Accuracy in detecting truths and lies: Documenting the "veracity effect." Communication Monographs, 66, 125-144. Masip, J., Garrido, E. & Herrero, C. (2002). Yearbook of Legal Psychology. McCornack, S.A. & Parks, M.R. (1986) Deception Detection and Relationship Development: The Other Side of Trust. Pantazi, M., Klein, O. & Kissine, M. (2020). Is justice blind or myopic? An examination of the effects of meta-cognitive myopia and truth bias on mock jurors and judges. Judgment and Decision Making, 15(2): 214–229.