Cognitive biases
A field guide to the mental shortcuts that trip everyone up — one short, practical page each.
Judgement
Anchoring effect
The first number we see tends to drag our later estimates toward it.
Confirmation bias
We tend to look for, and believe, evidence that fits what we already think.
Illusion of control
We often feel we can steer outcomes that are mostly down to luck, especially when we get to make choices.
Negativity bias
Bad experiences and information tend to affect us more strongly than good ones of the same size.
Overconfidence
We often think we know more, or do better, than we actually do.
Planning fallacy
We expect our own tasks to go faster and smoother than similar tasks usually do.
Probability
Base-rate neglect
We focus on vivid details of a case and forget how common the outcome is overall.
Conjunction fallacy
We rate a detailed story as more likely than a simpler one, even though logically it can't be.
Gambler's fallacy
We expect random streaks to 'even out', as if chance had a memory.
Survivorship bias
We study the cases that survived and forget the ones that dropped out, so success looks easier and more predictable.
Decisions and choices
Endowment effect
Owning something can make it seem worth more than we would have paid to get it.
Framing effect
The same facts can lead to different choices depending on how they are worded.
Loss aversion
Losing something tends to feel worse than gaining the same thing feels good.
Present bias
We make patient plans for the future, then choose the easy option when the future becomes now.
Status quo bias
We tend to stick with the current option or the default, simply because it is already there.
Sunk cost fallacy
We keep going with something because of what we've already put in.