Evidence: supported

• Asch conformity experimentstype: effect · evidence: supported

  In Solomon Asch's experiments in the 1950s, people had to say which line was as long as another, after a group had unanimously given an obviously wrong answer.

• Availability heuristictype: effect · evidence: supported

  We judge how often something happens by how easily examples come to mind.

• Bystander effecttype: effect · evidence: supported

  The more witnesses there are to an emergency, the less willing each of them is to help.

• Compoundingtype: mental model · evidence: supported

  When gains are added to the base and go on to earn gains of their own, growth is exponential, not linear.

• Confirmation biastype: effect · evidence: supported

  People tend to seek, choose and interpret evidence in favour of what they already believe.

• Conjunction fallacytype: effect · evidence: supported

  A more detailed story seems more probable than part of it, although every added detail makes it less probable.

• Consider the oppositetype: technique · evidence: supported

  Before drawing a conclusion or judging a piece of evidence, you ask yourself what you would think if things were the other way round.

• Cost of action vs cost of inactiontype: mental model · evidence: supported

  Doing nothing is also a choice, with its own costs.

• Curse of knowledgetype: effect · evidence: supported

  Once you know something, it is hard to imagine how someone who doesn't know it thinks.

• Decoy effecttype: effect · evidence: supported

  A third option, clearly worse than one of the two main options, makes that option look better and get chosen more often.

• Default effecttype: effect · evidence: supported

  A pre-selected option, the one that applies if you do nothing, is chosen far more often than when it has to be chosen actively.

• Diminishing returnstype: mental model · evidence: supported

  Each extra unit of a good thing usually brings less than the one before.

• Dunning-Kruger effecttype: effect · evidence: supported

  People with the weakest scores on a test overestimate their performance the most.

• Facial feedbacktype: effect · evidence: supported

  The idea that your facial expression influences your emotions, for example that smiling makes you a little happier.

• Fundamental attribution errortype: effect · evidence: supported

  When we see someone do something, we tend to explain it by who they are rather than by the situation they are in, even when the situation explains everything.

• Gambler's fallacytype: effect · evidence: supported

  After a run of identical outcomes in a game of chance, we expect the opposite outcome to be "due", although the odds haven't changed.

• Habit formationtype: effect · evidence: supported

  A habit forms by repeating the same behaviour in the same context until it becomes automatic.

• Hindsight biastype: effect · evidence: supported

  Once we learn how something turned out, it seems to have been predictable and we feel "I knew it all along".

• Interleavingtype: technique · evidence: supported

  When you practise, you mix the types of problems instead of taking them one at a time, in blocks.

• Loss aversiontype: effect · evidence: supported

  A loss weighs more than a gain of the same size.

• Mental contrasting (WOOP)type: technique · evidence: supported

  You imagine what you want to achieve, then the obstacle that could stop you, then an "if the obstacle comes up, then I will…" plan.

• Milgram experimenttype: effect · evidence: supported

  In Stanley Milgram's experiments of 1961–1962, many ordinary people kept giving what they believed were painful electric shocks to a stranger because an experimenter asked them to.

• Negativity biastype: effect · evidence: supported

  A loss, a criticism or a bad day counts for more than a gain, a compliment or a good day of the same size.

• Peak-end ruletype: effect · evidence: supported

  When we remember an experience, we judge it mostly by its most intense moment and by how it ended, and its length matters surprisingly little.

• Planning fallacytype: effect · evidence: supported

  People usually underestimate how long their own projects will take, even when they know that similar projects ran late.

• Pygmalion effecttype: effect · evidence: supported

  The Pygmalion effect is the idea that pupils from whom teachers expect more end up actually doing better.

• Sunk costtype: effect · evidence: supported

  Money, time or effort already spent won't come back, whatever you decide now.

• Temptation bundlingtype: technique · evidence: supported

  You allow yourself a treat, such as a TV series, an audiobook or a podcast, only while doing something useful that you keep putting off, such as exercise.

• Via negativatype: mental model · evidence: supported

  Sometimes the best improvement is to take something away, not to add.