There is a good list on Wikipedia. I did a course on them in my first semester of my psychology degree. On this page I want to list each cognitive bias or illusion (I’m going to use those interchangeably) and provide two examples.

Anchoring bias

Anchoring bias is the tendency to overly rely on the first piece of information we encounter (the ‘anchor’) when making decisions.

  1. A shopper sees a shirt originally priced at €50, but now on sale for €30. The shopper feels like they are getting a good deal because they are anchored to the original price of €50.

  2. In a negotiation, the person who makes the first offer often has an advantage because that number sets the anchor for the rest of the negotiation.

Confirmation bias

Confirmation bias is our tendency to selectively search for and consider information that confirms our existing beliefs.

  1. A person who believes in astrology may pay more attention to instances where their horoscope accurately predicted an event, and ignore instances where it did not.

  2. A political enthusiast may only read news from sources that align with their own political beliefs and dismiss any contradicting views as misinformation or propaganda.

Hindsight bias

Hindsight bias involves seeing past events as being more predictable than they were before they occurred. This cognitive illusion can lead to overconfidence in one’s ability to predict outcomes, and may result in poor decision-making. It is often referred to as the “knew-it-all-along effect.”

  1. After a sports game, a fan might claim they “knew all along” that their team would win, even though the outcome was uncertain before the game.

  2. Following a stock market crash, people often believe they could have predicted the crash, when in reality such financial events are highly unpredictable and complex.

Self-serving bias

Self-serving bias is our tendency to attribute positive outcomes to our own skills and abilities while blaming negative outcomes on external factors or bad luck.

  1. A student who does well on a test might attribute their success to their intelligence and hard work, but if they fail, they might blame it on the test being too hard or not having enough time to study.

  2. An employee who receives praise for a project might credit their own skills and dedication, but if the project fails, they might blame it on insufficient resources or lack of support from colleagues.

Availability heuristic

The availability heuristic involves making judgments about the probability of events based on how easy it is to think of examples. Our minds tend to focus on information that is easily accessible and immediate.

  1. When people overestimate the likelihood of plane crashes because these tragic events are widely covered in the media, despite the fact that statistically, air travel is much safer than car travel.

  2. After watching a news report about a house fire, a person might suddenly feel the need to check their smoke detectors more frequently, perceiving the risk of a house fire to be much higher than it actually is.