Confirmation Bias: Why We Make Poor Judgment & Bad Decision

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In an experiment published in 1960, English psychologist Peter Wason challenged participants to identify a rule applying to triples of numbers. In the experiment, the participants were told that – 2, 4, 6 – fits the rule. Participants then could generate their own triples and the experimenter told them whether or not each triple conformed to the rule.

English psychologist Peter Cathcart Wason

English psychologist Peter Cathcart Wason

When the participant came up with 3, 5, 7, the experimenter then told the triples to fit the rule. Then, the participants would need to come up with the rule of the triples.

So, the rule is “numbers with an increment of 2”? No, that’s not the rule.

It didn’t matter if the rule was wrong, the participants were free to come up with another triple to collect more information in assisting them to identify the rule.

While the actual rule was simply “any ascending sequence”, the participants are facing great difficulty in identifying it. Often, the participants came up with rules that were far more specific, such as “The last number is the multiple of the first two numbers”.

The participants seemed to test only positive examples – triples that obeyed their hypothesized rule. For example, if they thought the rule was, “Each number is four greater than its predecessor”, they would offer a triple that fit this rule, such as (11,15,19) rather than a triple that violates it, such as (11,12,17).

That’s what Peter Wason coined this finding with the term – Confirmation Bias.

We Believe What We Want to Believe

Imagine you call your spouse up after an argument, and he never picks up the call, nor leaving you a text message or calling you back after some time. It’s easy for you to jump to the conclusion that he is trying to avoid you, or having fun with someone else out there. You then start to seek for more evidence – calling his friends, texting him non-stop – to find out if he is really avoiding you.

Have you seen the problem yet? The danger is that, in fact, you leave this belief – your spouse is avoiding you – unchecked, and then act as if it’s true.

Confirmation bias is a common mental error occur when a pre-existing belief interferes the way we think, make decisions, and take actions. When we have a belief or hypothesis in mind that we think it’s true, consciously or unconsciously, we are more likely to seek more evidence to prove it right.

We open our eyes to more positive examples that strengthen the belief but tend to ignore everything else that disprove and violate it. We no longer perceive the circumstances objectively. In fact, we pick only a part of the data that make us feel good because it supports our prejudices.

In sum, people (read: we) are prone to believe what they want to believe. Seeking to confirm our beliefs comes naturally. This becomes even stronger when the beliefs are emotionally connected to us for the longer period of time.

It happens all the time in our day to day life without our awareness. For example:

  • When we are in an argument, we filter our every information that prove our opposition right and prove us wrong. Sometimes, we even went to the extent of being irrational on cool hard facts.
  • After we face multiple rejections in business (or anything else), we start to find evidence that we can never get approve or succeed on our pursue. We create stories before we validate our ideas that make us feel better, either by ignoring the calculated risks or back up in the face of fear.
  • We even go to the extent of destroying ourselves by pre-confirmed beliefs passed down by others – parents, teachers, friends, employers, etc. – without any validation, when it shapes your identity with certain limitation.

Better Decision Making

While it may look counterintuitive and contradict, the best way to really prove our belief and hypothesis are right is to seek for evidence that disproves them. This is where disconfirmation comes in handy and much more useful when come to making important decisions.

There is no easy step to break free from the confirmation bias because it’s here to aid us in making fast decisions and learning in the first place. Instead of letting this interfere the ability of you making better decisions, use these thinking models to make really filter our confirmation bias in your decision-making process.

. . .

Scientific Thinking. When scientist and researcher want to prove their observation, they make a hypothesis and carry out both positive experiment – set out to prove them right, and negative experiment – set out to prove them wrong. Although there are cases that some scientists and researchers did fall into the trap of confirmation bias to carry out only positive experiments, but more and more scientists aware of this psychology bias and start to adopt the new way to prove (and disprove) their finding.

Data Centric Thinking. This works extremely well for businesses, especially startup. Smart entrepreneur set up key measurable metric to filter out the involvement of emotions when coming to important decision making. It’s clear that “gut feeling” is somehow critical in business, so the collected data is there really just to aid the decision-making process, rather than making important decisions fully faced on “gut feeling”. It also acts as a piece of data to keep track the progress of the business.

Feedback Thinking. Validate the pre-existing beliefs or concepts before making any conclusion. In fact, avoid making a conclusion in the beginning stage, set out to test your ideas or decisions. Then, gain feedback to adjust along the progress. With this thinking model, we will be able to remove the fear of making mistakes because it’s just a form of feedback.

. . .

These thinking models will aid you to make better decisions in many areas of your life. It could improve your relationship by stopping you to judge people without a full understanding of that person. Besides, it also helps you to question your own beliefs and ideas to make a better decision without attached to your prejudices.

Put Confirmation Bias Into Good Use

Confirmation bias is being coined as an error of our decision-making process, but the psychology model has its purpose. Framing certain facts in your daily life will help you learn and make decision faster such as you shouldn’t jump off a tall building and expecting yourself to survive uninjured.

Besides, mental framing also works well in building up a peak emotional state early in the morning. Frame your mind to focus how lucky you are and appreciate all the little things help you do better throughout the day. It does no harm to start a day with a positive emotional state.


  1. I was inspired to dig into the research of the Confirmation Bias by this video by Veritasium. You should watch it if you want to see how people react with the exact experiment carried out by psychologist Peter Watson.
  2. As I write, I thought of these critical thinking models that help to break us out from confirmation bias. Yes, I create and made up those words and strategies. But then I found that those terms and critical thinking models actually exist before I invented them. My point is, I might not be 100% accurate with those terms since I come up with them (with my own definition) before I do serious research on them.
  3. The interesting point is, I’m going to dig into those critical thinking models and write about them pretty soon. Will update these article that time.

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  • Aravind Balla

    A great read I say!