Cognitive Biases: Why We Make Irrational Decisions

Explore some classic biases in everyday thinking—and how to avoid them.


Over the decades psychologists have discovered all kinds of biases in how we think.


Some tell us why the incompetent don’t know they’re incompetent, others why it’s difficult to estimate our future emotions and some why we feel more transparent to others than we really appear.


Many of these biases result from our minds using little short-cuts to help us navigate through a complicated world. Unfortunately the result can be that we reach irrational decisions.

Understanding how these biases operate may help you make better decisions in all sorts of situations, both at home and work. More than that, though, it will help you understand your own mind.

• The Dunning-Kruger Effect: Why The Incompetent Don’t Know They’re Incompetent – The Dunning-Kruger effect is the finding that the poorest performers are the least aware of their own incompetence.
• The Worse-Than-Average Effect: When You’re Better Than You Think – People underestimate their ability at stereotypically difficult tasks like playing chess, telling jokes, juggling or computer programming.
• Why You’re a Sucker for the Impact Bias – Why we are often poor at predicting how future events will affect us emotionally.
• The Hindsight Bias: I Knew It All Along! – How to correct for a bias that stops us learning from our mistakes.
• How to Overcome the Egocentric Bias – Perspective-taking offers a way around the egocentric bias.
• See How Easily You Can Avoid The Memory Bias – The type of memories we retrieve to make decisions are often biased to unusual examples that are either very positive or very negative.
• Why Your Future Self is an Emotional Mystery: The Projection Bias – People directly project their current emotional state into the future, forgetting their current feelings will likely change.
• How To Avoid Choosing the Wrong Job or House: Fight the Distinction Bias – There are reliable biases in the way we make comparisons that mean we don’t always choose what maximises our future happiness.
• 4 Belief Biases That Can Reduce Pleasure – How beliefs can bias our decisions.
• Does Delaying Decisions Lead to Better Outcomes? – Decision-makers move away from the default after a delay.
• The Belief in a Just World: A Fundamental Delusion – Does what goes around come around? Do you get what’s coming to you? Do you reap what you sow?
• Why Society Doesn’t Change: The System Justification Bias – Have you ever wondered why society hardly ever changes?
• The Availability Bias: Why People Buy Lottery Tickets – Shark attacks, murders and lottery wins: vivid events are more likely to affect judgement.
• The Illusion of Transparency – Other people can’t read your mental state as well as you think.
• The Illusion of Control: Are There Benefits to Being Self-Deluded? – Do people always overestimate how much they control their lives?
• The Endowment Effect: Why It’s Easy to Overvalue Your Stuff – A strange thing happens in the mind when you buy something.
• Illusory Correlations: When The Mind Makes Connections That Don’t Exist – Why do CEOs who excel at golf get paid more, despite poorer stock market performance?
• The Anchoring Effect: How The Mind is Biased by First Impressions – A psychological bias that illuminates how we negotiate, predict our emotions, agree a price and much more…
• The Confirmation Bias: Why It’s Hard to Change Your Mind – People search for information that confirms their view of the world and ignore what doesn’t fit.
• The Well-Travelled Road Effect: Why Familiar Routes Fly By – What a simple cognitive bias teaches about how to live our lives.
• The Sobering Up Effect: Why People Get More Pessimistic As The Moment of Truth Gets Closer – When the chips are about to fall, mentally we brace ourselves.

About the author


Psychologist, Jeremy Dean, PhD is the founder and author of PsyBlog. He holds a doctorate in psychology from University College London and two other advanced degrees in psychology.


He has been writing about scientific research on PsyBlog since 2004. He is also the author of the book “Making Habits, Breaking Habits” (Da Capo, 2003) and several ebooks