Political debates, public interest issues, medical diagnosis, conspiracy theories, entrepreneurship: these are just a few of the areas affected by our tendency to preserve personal identity by confirming existing prior ideas that reflect our social group or personal beliefs (Brain Week, 2018).
This phenomenon describes people’s tendency to favor information that validates preconceptions, assumptions, and personal beliefs, regardless of the veracity of such information. Confirmation bias was first acknowledged and named in the 1960s by Peter Wason, a cognitive psychologist at University College London and a pioneer in the psychology of reasoning (The Decision Lab, 2020).
The reasons behind this bias can be linked to the need to avoid cognitive dissonance and help maintain and confirm our sense of self-identity (Festinger, 1957). Confirmation bias is nothing more than a cognitive shortcut we resort to when gathering and interpreting information. Since evaluating evidence takes time and energy, our brains automatically look for such mental shortcuts to make the process more efficient.
What we do actually makes a lot of sense. People need to process information quickly but incorporating new information and forming new explanations or beliefs takes a longer time. That is the reason why we have adapted to prefer the option that requires the least effort, often out of necessity.
This phenomenon might seem more evident and widespread today, as we are exposed to a substantial amount of information online. We are also adapting to this information splurge – as algorithms are trained to selectively guess what information we would like to see based, among other things, on past click-behavior or search history So, we become separated from information that disagrees with our viewpoints. But the truth is that the phenomenon has always existed.
Confirmation bias was already known back in Ancient Greece. Thucydides (460 B.C. – 395 B.C.), historian and among the leading exponents of Greek literature, remarked that ” […] it is a habit of [hu]mankind to entrust to careless hope what they long for, and to use sovereign reason to thrust aside what they do not fancy.”
In 1620, the English philosopher Francis Bacon, in his book Novum Organum Scientiarum, stated that “human understanding, when it has once adopted an opinion draws all things … to support and agree with it. And though there be a greater number and weight of instances to be found on the other side, yet these it either neglects and despises or … sets aside and rejects in order that by this great and pernicious predetermination, the authority of its former conclusions may remain inviolate.“
There is plenty of further literary evidence regarding the fact that the concept of confirmation bias has always existed, such as that of Marcel Proust, author of In Search of Lost Time, who suggested that jealousy itself is a consequence of confirmation bias: “It is astonishing how jealousy, which spends its time inventing so many petty but false suppositions, lacks imagination when it comes to discovering the truth.“
Confirmation bias can help us explain several phenomena, such as why racist or sexist stereotypes endure over time. A sexist person may overlook all kinds of empirical evidence about different genders being equally good at math or equally able to take care of their children, as it is much quicker to recognize more isolated or uncommon cases that confirm their stereotyped, prior ideas.
Similarly, a racist person may not notice all the people of different ethnicity who work hard to support their families, pay taxes and behave as honest citizens: they will be paying much more attention to isolated cases of misconduct in general, when performed by a minority, while overlooking the same misconduct performed by people who belong to their own ethnic group.
This bias also explains why some conspiracy theories are successful even when they are proven to be based on falsehoods and absurdities. The typical proponent of a conspiracy thesis will spend time defending and disseminating crumbs of empirical evidence in support of their theory, while leaving out all the evidence that disproves it (Angner, 2017).
Scientific research in the field of psychology suggests that this cognitive distortion is due to several factors. First, people often tend not to see empirical evidence that contradicts their ideas, while they are much more likely to find evidence that confirms them. Second, when the evidence is not as clear or is ambiguous, and lends itself to dual interpretations, people naturally tend to prefer interpretations that are in line with their own thinking. Finally, people are stricter about the criteria by which they accept evidence that can refute their ideas than they are when faced with evidence that can confirm them (Angner, 2017).
A study conducted using magnetoencephalography (MEG) and recently published in Nature Communications found that ignoring evidence against one’s position is a process particularly evident when subjects are extremely confident in their decisions. According to the research, high levels of confidence lead to a striking modulation of post-decision neural processing, such that the processing of evidence confirming one’s hypothesis is amplified, while the processing of disconfirming evidence is greatly reduced, if not abolished.
If the study identifies overconfidence as a facilitator of the cognitive distortion caused by confirmation bias, it is equally true that metacognitive processes, i.e., the ability to be aware of and able to control cognitive processes, are the weapons we can and should equip ourselves with to counter and limit the effects of this cognitive distortion of which we are often victims without realizing it (Rollwage et al., 2020).
