Cognitive Biases

Twenty-six mental shortcuts that lead good thinkers astray, each with an everyday example.

A bias is easier to catch in yourself once you can name it. Each card describes one, such as anchoring, the sunk cost fallacy or survivorship bias, and asks you to pick its name from four. The answer adds an everyday example of it at work: at the shops, in meetings, with money.

All 26 cards

  1. Favouring information that supports what you already believe, and discounting what doesn’t.

    Confirmation bias

    Example: Reading only reviews that agree with the purchase you already made.

  2. Leaning too heavily on the first number or fact you hear when making a judgment.

    Anchoring

    Example: A “was $200, now $120” tag makes $120 feel cheap, whatever the item is worth.

  3. Judging how likely something is by how easily examples come to mind.

    Availability heuristic

    Example: Fearing plane crashes more than car crashes after seeing one on the news.

  4. People with little skill at something overrating their ability at it.

    Dunning–Kruger effect

    Example: Someone who has read one article on vaccines feeling more certain than an immunologist.

  5. Sticking with something because of what you’ve already put in, rather than what it will give you from here.

    Sunk cost fallacy

    Example: Finishing a bad film because you paid for the ticket.

  6. Seeing past events as having been more predictable than they were.

    Hindsight bias

    Example: “I knew that stock would crash.”

  7. Adopting beliefs or behaviour because many other people have.

    Bandwagon effect

    Example: Buying a coin because everyone at work is talking about it.

  8. Drawing conclusions from the successes you can see while missing the failures you can’t.

    Survivorship bias

    Example: “Dropouts become billionaires” ignores the far larger number of dropouts who didn’t.

  9. Giving bad experiences more weight than equally good ones.

    Negativity bias

    Example: Remembering one critical comment over ten compliments.

  10. Losing something feeling worse than gaining the same thing feels good.

    Loss aversion

    Example: Refusing a coin flip that wins $110 or loses $100.

  11. Letting one good trait colour your view of everything else about a person or thing.

    Halo effect

    Example: Assuming an attractive candidate is also more competent.

  12. Blaming other people’s actions on their character, but your own on circumstances.

    Fundamental attribution error

    Example: The driver who cut you off is a jerk; when you do it, you’re late for something important.

  13. Believing bad things are less likely to happen to you than to others.

    Optimism bias

    Example: Skipping insurance because accidents happen to other people.

  14. Underestimating how long a task will take, even when similar tasks have run over before.

    Planning fallacy

    Example: Expecting the kitchen renovation to take two weeks, again.

  15. Preferring things to stay as they are, even when a change would be better.

    Status quo bias

    Example: Staying on a pricier phone plan because switching feels like a hassle.

  16. Reacting differently to the same facts depending on how they are presented.

    Framing effect

    Example: A surgery with a “90% survival rate” sounds safer than one with a “10% death rate”.

  17. Believing past random events change the odds of future ones.

    Gambler's fallacy

    Example: “Red has come up five times, so black is due.”

  18. Overestimating how much other people notice your appearance and behaviour.

    Spotlight effect

    Example: Worrying all evening about a small stain nobody else saw.

  19. Forgetting what it’s like not to know something, which makes it hard to explain.

    Curse of knowledge

    Example: An expert using jargon without realising the audience is lost.

  20. Valuing something more just because you own it.

    Endowment effect

    Example: Asking far more for your used car than you would pay for the same one.

  21. Giving more weight to recent events than older ones.

    Recency bias

    Example: Judging a whole year’s performance by the last month.

  22. Ignoring how common something is in general when judging a specific case.

    Base rate neglect

    Example: Assuming a quiet, bookish person is more likely a librarian than a salesperson, though salespeople vastly outnumber librarians.

  23. Valuing things more because you made or assembled them yourself.

    IKEA effect

    Example: Loving your wobbly self-built shelf more than a better one from the store.

  24. People being less likely to help someone when others are around.

    Bystander effect

    Example: A crowd walking past someone who has collapsed, each assuming someone else will act.

  25. Judging an experience mostly by its most intense moment and how it ended.

    Peak–end rule

    Example: A holiday remembered as bad because of a miserable flight home.

  26. Liking things more simply because they are familiar.

    Mere exposure effect

    Example: A song you disliked growing on you after hearing it everywhere.