Home > Cognitive Bias, Education > When you read this, you will only look out for what confirms your prior beliefs

When you read this, you will only look out for what confirms your prior beliefs

Or not. But probably not. Science has demonstrated that we have a natural tendency to search for and interpret information in a way that only confirms our prior beliefs or values. Ever been doing research for a paper in a class and only searched for information and evidence that supports your argument? Now answer this. While doing that, have you ever just let yourself skip by that evidence and those examples that went against your paper thesis? I know I have. What you probably didn’t realize, though, is that what you’re doing is exhibiting what is known as confirmation bias. And you might think big deal, right? Well, it kind of is. When you ignored those counterarguments and that contradictory evidence, you were arguing through a lens that only took into account one side of the story and one version of the truth. In order to make a complete and impartial argument we must consider all of the evidence and all of the facts. Confirmation bias hinders our ability to do this. And unfortunately, we have no defense to confirmation bias–it’s an automatic process that occurs without us even being aware of it happening. Understanding the nature of confirmation bias and its effects, however, can help reduce the detrimental effects it is known to have on us and society. 

This is what confirmation bias turns our research process into without us even realizing it!

To prove just how susceptible we are to the effects of confirmation bias, Peter Wason (1960) conducted a simple numbers task study. In the task, participants were asked to guess what the rule was for groups of three numbers. They were presented with “2-4-6” and then asked to give sets of three numbers that satisfy the rule. Each time the participants reported a group of three, they were told if they had gotten a correct sequence or not. The participants were also instructed to stop when they believed they figured out what the rule was. In the study, participants reported number sets of “4-8-10,” “6-8-12”, “20-22-24,” which were all correct number sets. Since they were told that these were correct, the participants believed they had figured out the rule and thus stopped trying out different number sets. However, they hadn’t gotten the rule correct because the rule was actually all sets of increasing numbers. The participants didn’t allow themselves a chance to figure this out, though, because they only tested sets that confirmed their belief of what the rule was and didn’t try out any other options. Thus, their error was in not testing sets that did not correspond to what they assumed the rule was. This simple study exposed the unintentional but meaningful impact confirmation bias has. Implicitly, these students were trying to confirm their hypothesis of what the rule was rather than falsify it, which caused them to generate a false and ineffective means to figure out what the rule was. The results of this study prove that even in the smallest and most ordinary tasks we have a tendency to follow all and only what falls under our beliefs as well as discount what could be contrary to them.

While this numbers task may seem like a meaningless case, the principle of confirmation bias is what counts. In other words, the danger lies in the fact that when we confirm our own beliefs we are also partaking in an ignoring and disregarding of contradictory evidence, data or ideas. This impairs our ability to make true and fair judgements because we do not give ourselves the opportunity to evaluate all the evidence and then make a proper decision. And this is where confirmation is most dangerous: in its ability to significantly harm society by distorting evidence based decision making. 

Consider for example, a police detective who potentially wrongfully identifies a guilty suspect early in an investigation and seeks only evidence that confirms that that person is responsible for the crime. Factor in the phenomena that people are more convinced when they see others are presenting evidence with high confidence rather than low confidence and it becomes believable that jury decisions can be compromised. If an eye witness is confident he or she saw someone commit a crime, the jury is more likely to treat this evidence as valid even if it is not! Think about that for a second. Justice is served in our country on the basis of potentially flawed and incomplete processes. 

The outcomes of numerous court cases have shown that juries still exhibit confirmation bias in their conviction decisions by serving “justice” on the basis of only a small portion of the evidence and ignoring evidence that supports what is contrary to what the jury believes happened.

Throughout history, African Americans have been marginalized and falsely convicted of crimes they did not commit. In these cases, confirmation bias has played a critical role in convincing the jury to interpret the evidence in a biased and subjective manner that is nowhere near true. The prosecutors were very methodical in how they manipulated the evidence to paint the picture that the defendant was guilty, even though this was completely false! They did this by solely emphasizing the evidence that supports a guilty claim while completely disregarding any evidence that would indicate the opposite.

Portrayals of black Americans as violent, ruthless savages in the media has contributed to stereotypes and confirmation bias because upon meeting and judging black Americans, those in charge of enforcing justice will hold those expectations and stereotypes in mind—limiting their ability to judge impartially. 

The Central Park Jogger case made national headlines and not for the right reasons. Titles like these contributed to the false impression that these boys were not only guilty, but animal like savages who viciously attacked a defenseless jogger.


One prime example of the criticality of confirmation bias fueling false testimony is the Central Park jogger case in which five African American and latino teenagers were falsely accused and convicted of assaulting and raping a female jogger. The prosecution team focused solely on evidence that supported the boys being guilty while completely ignoring any evidence that proved their innocence. Well known newspapers in New York and across the country published articles that described the boys as “wolves” who viciously attacked the girl in a pack–contributing to an assumption of guilty before the trial had even begun! And when the investigation did actually commence, police officers, investigators and detectives were told by the District Attorney that the boys were indeed guilty prior to even speaking with or interrogating the boys. By planting this assumption of guilty, guilty, guilty to all those who were supposed to view the case impartially, it became impossible for this to be viewed with an open mind. Most importantly, the investigators who met with and interrogated the boys did so with the sole intention of hearing what they wanted to hear: confessions from the boys that admitted they committed this crime—rather than the boys account of what actually happened. Using stress, fear and intimidation the investigators did not accept the boys testimony and continued to demand that the boys confess. They kept the boys there for many long hours and also gave the boys false promises such as if you confess we will let you go home. Finally, the boys gave in and admitted to some extent that they had committed the crime. However, they had fabricated these confessions out of the pressure the interrogators, media and society were placing on them by forcing them to believe they were guilty of this crime they did not commit! When their DNA and blood tests came back and proved to have no connection with the crime scene, you would think it would be concluded there was no way the boys could have committed this crime, right? Wrong! Despite this, the jury based their conviction solely on the shaky and unreliable confessions of the boys while completely discrediting the concrete evidence that proved the boys innocence. Without a doubt, confirmation bias completely distorted and destroyed justice in this case. The prosecution team only used evidence that supported their initial belief that the boys were guilty without even considering the possibility that they weren’t. Any evidence that indicated otherwise was suppressed because they simply couldn’t and wouldn’t consider anything that diverged from their belief that the boys were guilty of a crime they clearly did not commit.

Confirmation bias has also proven to be a factor in medical practices and emergency care. This is because due to the increased volume and severity of emergency care, medical professionals must rely on heuristics (mental shortcuts) as their guide to diagnose and treat their patients. This reliance on heuristics in decision making has led medical professionals to give more value to confirmatory data and disregard to disconfirmatory data. As you can imagine, giving a faulty treatment to a patient in emergency care can have the most severe consequences. Thus, it is vital that medical professionals recognize confirmation bias as a shortcoming in medical decision making. To improve accuracy, medical professionals must rely on the completeness of the scientific method, metacognition and cognitive forcing strategies to ensure they are considering and valuing all of the data equally to arrive at the appropriate conclusion. 

We’ve seen the damaging effect of confirmation bias now, right?

Now consider this.

As kids, we are taught to listen to and believe what we are taught. We commonly form our own beliefs and values based on what we hear from family, close friends and other individuals that we respect and look up to. And we’ve obeyed…most of the time. How many of us could say that we openly rejected our parents and role models beliefs and values at a young age? Not many, right? Absorbing for such a prolonged period of time, we have internalized these beliefs and values–they have become implicitly ingrained in us. But have you ever considered if you see the world through a lens in which you see the world as you choose to see it rather than how it actually is? In other words, is everything we look for and perceive implicitly done in a way that proves our core values and beliefs? Perhaps yes, perhaps no. What we know without a doubt, though, is that confirmation bias is something that harms us all. We must be aware of it and its potential to push us to biased and false conclusions. We must force ourselves to view every side of every argument with an open mind. And lastly, we must understand that even though we will never completely eliminate confirmation bias, we can certainly take the necessary steps to ensure that we minimize its harmful effects that don’t just affect us but the well being and purity of society as a whole.

Works Cited/References

Pines, J. (2008, June 28). Profiles in Patient Safety: Confirmation Bias in Emergency Medicine. Retrieved November 27, 2020, from https://onlinelibrary.wiley.com/doi/abs/10.1197/j.aem.2005.07.028

Kappes, A., Harvey, A.H., Lohrenz, T. et al. Confirmation bias in the utilization of others’ opinion strength. Nat Neurosci 23, 130–137 (2020). https://doi.org/10.1038/s41593-019-0549-2

Miglani, A. (2020, August 27). Confirmation Bias in the Central Park Jogger Case. Retrieved November 27, 2020, from https://medium.com/@aadimiglani/confirmation-bias-in-the-central-park-jogger-case-a411164e8a22

Pohl, R. F. (2004). Cognitive Illusions: A Handbook on Fallacies and Biases in Thinking, Judgement and Memory. Retrieved November 27, 2020, from https://www.google.com/books/edition/Cognitive_Illusions/MS5Fr8safgEC?hl=en

Nickerson, R. (n.d.). Confirmation Bias: A Ubiquitous Phenomenon in Many Guises – Raymond S. Nickerson, 1998. Retrieved November 02, 2020, from https://journals.sagepub.com/doi/abs/10.1037/1089-2680.2.2.175 http://pages.ucsd.edu/~mckenzie/nickersonConfirmationBias.pdf

Bogert, C. (2019, May 31). Op-Ed: How the media help drive harsh criminal justice policies. Retrieved November 27, 2020, from https://www.latimes.com/opinion/op-ed/la-oe-bogert-central-park-jogger-media-20190531-story.html

Schwind, C., Buder, J., Cress, U., & Hesse, F. (2011, October 13). Preference-inconsistent recommendations: An effective approach for reducing confirmation bias and stimulating divergent thinking? Retrieved November 27, 2020, from https://www.sciencedirect.com/science/article/pii/S0360131511002478

Dwyer, Jim. “The True Story of How a City in Fear Brutalized the Central Park Five.” The New York Times, The New York Times, 30 May 2019, www.nytimes.com/2019/05/30/arts/television/when-they-see-us-real-story.html.

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