Truth or lies: how do we decide what to believe?

This post is also available in Dutch.

Would you believe that a) an octopus has three hearts, or b) Einstein performed poorly in maths at school? Most people find b more convincing, yet is it false. When we are uncertain, how do we choose what to believe?

Today, we often hear that we are living in a post-truth and fake news era, that is, in a world in which facts can be overshadowed by opinions. However, disinformation and its cousin propaganda are not creations of our times. By far one of the most tragic and relatively recent examples of propaganda is the one spread in Nazi Germany. But even before that, the circulation of falsehoods can be traced back as far as the 16th century when the first newspapers emerged. Even though falsehoods being shared in the media is not a recent phenomenon, we have not yet learned how to tell which information is true or false. What factors contribute to our decisions about what is true or false?

Repetition. Research has shown that when participants are presented with various statements, of which some are repeated and some appear only once, the information that is repeated appears more truthful than the information that is seen for the first time. The likely cause of this effect is that it is easier for us to process information that we have come across before. This ease of processing creates a feeling that the statement that we are seeing is correct.

Photographs. In one experiment, participants read various statements, which tapped general knowledge. For instance, “The first windmills were built in Persia”. Half of all statements in the experiment were presented with a generic photo (a windmill in the middle of nowhere, so that one could not tell where it was located). Despite this, the results revealed that the statements that appeared together with photos were judged more truthful than those without photos. This phenomenon probably occurs because in real life, most things that we see are real and we apply the same principle to statements that appear in the context of photographs.

Print style and sayings. Apart from photos, even the style of print can modulate our decisions regarding what we consider real. Statements presented in high contrast as in The capital of Madagascar is Toamasina appear more truthful than The capital of Madagascar is Toamasina. The influence can also be exerted by sayings that rhyme vs. those that do not. For example, it was found that rhyming statements, such as “What sobriety conceals, alcohol reveals” were judged as more apt compared to “What sobriety conceals, alcohol unmasks”. The effect of rhyming sayings, similarly to repetition, occurs due to enhanced processing fluency.

What conclusions can we draw based on all these experiments? It appears that how we judge truth can be affected by a variety of basic aspects, such as the frequency with which certain information is presented, whether the information is accompanied by visuals, and whether it rhymes. Information that is false but feels intuitive and easy to understand will tend to be perceived as truth.

At last, let’s revisit the two statements, a and b. While Einstein was not an exemplary student, he excelled in maths. The reason why b may feel as a truthful statement is that many of us have heard various stories about Einstein, and this is sufficient to facilitate the acceptance of b.

Original language: English

Author: Julija Vaitonyte
Buddy: Rebecca Calcott
Editor: Ellen Lommerse
Translator: Wessel Hieselaar
Editor translation: Jill Naaijen

Image by Arek Socha via Pixabay

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