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    Thinking Dictionary

    Cognitive shortcuts

    What it is

    Cognitive shortcuts, also called heuristics, are rules of thumb the brain uses to make quick judgements. They ignore some of the available information so we can decide fast. Most of the time they work well enough. Sometimes they work even better than slow, complicated methods.¹ But they also go wrong in ways that are predictable.²

    These shortcuts are typical errors of fast thinking. The Fast and slow thinking entry explains the two modes. This entry looks at four specific shortcuts.

    Four common shortcuts

    Anchoring. The first number you see pulls your estimate towards it, even when that number is irrelevant. In one set of experiments, experienced judges and lawyers were given a sentencing demand before deciding on a sentence. Their decisions moved towards that number, even when it was clearly irrelevant, said to be chosen at random, or set by dice they had rolled themselves. Their experience did not protect them.³

    Availability. Things that come to mind easily seem more common than they are. In a classic study, people judged how often different causes of death happen. They overestimated rare causes and underestimated common ones. This was partly because of how often people hear about each cause and how memorable it is. Telling people about the bias in advance didn't help.⁴

    Representativeness. We judge how likely something is by how well it fits our mental picture of a typical case. In doing so, we tend to ignore how common it is in the first place.² The Probabilistic reasoning entry explains why how common something is, called the base rate, matters so much.

    The halo effect. One good trait colours how we judge everything else about a person. In one experiment, students watched the same instructor in two versions. When he acted warm, students rated his appearance, manner, and accent as appealing. When he acted cold, they rated the very same things as irritating. And they didn't realise that his warmth had affected their judgements.⁵ A large review found that attractive people are judged and treated more positively, even by people who know them.⁶

    Why it matters

    These shortcuts are not signs of stupidity. They affect experts too, as the judges show.³ And because they happen automatically, simply knowing about them helps little.⁴˒⁵

    They also share a common root. In each case, the mind quietly swaps a hard question for an easier one. "How common is this?" becomes "How easily can I think of an example?" "Is this person competent?" becomes "Do I like them?"

    A note on famous findings that didn't hold up

    Some effects often listed alongside these shortcuts have not held up. A large project repeated 13 classic findings across many labs. Most of them replicated consistently, but some priming effects did not, including "flag priming" and "currency priming."⁷ Priming is the idea that brief exposure to a word or image changes later behaviour. The Fast and slow thinking entry has more on this.

    In everyday life

    • Prices. A shop shows a "recommended price" of 200 next to a sale price of 120. The first number is an anchor that makes 120 feel cheap.
    • Fear of flying. Plane crashes get huge news coverage, so they come to mind easily. That can make flying feel riskier than everyday dangers that rarely make the news.
    • Job interviews. A confident, likeable candidate may be rated as more competent across the board. That is the halo effect at work.

    The common trap

    The trap is thinking "smart people don't fall for these." Experts do, too.³

    The second trap is thinking "now that I know about them, I'm safe." Awareness alone helps little.⁴ Simple procedures help more.

    Some ways out:

    • Look up the real figures. Check official statistics instead of relying on what comes to mind.
    • Make your own anchor. Before seeing someone else's number, write down your own estimate.
    • Separate traits. Judge competence on evidence of competence, not on how likeable someone is.
    • Ask for the base rate. How common is this in general?

    Try it

    Ask two friends to guess the population of Copenhagen, separately. Ask the first: "Is it more or less than 50,000? What's your best guess?" Ask the second: "Is it more or less than 5 million? What's your best guess?" Compare their guesses. Then look up the real figure.

    Next, write down what you think are the three most common causes of death in your country. Then check the official statistics. Were any of your picks things that often make the news?

    Related concepts

    Fast and slow thinking · Confirmation bias · Probabilistic reasoning · Sample size · Credible sources · Regression to the mean

    Sources

    1. Gigerenzer, G., & Gaissmaier, W. (2011). Heuristic decision making. Annual Review of Psychology, 62, 451–482. https://doi.org/10.1146/annurev-psych-120709-145346

    2. Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185(4157), 1124–1131. https://doi.org/10.1126/science.185.4157.1124

    3. Englich, B., Mussweiler, T., & Strack, F. (2006). Playing dice with criminal sentences: The influence of irrelevant anchors on experts' judicial decision making. Personality and Social Psychology Bulletin, 32(2), 188–200. https://doi.org/10.1177/0146167205282152

    4. Lichtenstein, S., Slovic, P., Fischhoff, B., Layman, M., & Combs, B. (1978). Judged frequency of lethal events. Journal of Experimental Psychology: Human Learning and Memory, 4(6), 551–578. https://doi.org/10.1037/0278-7393.4.6.551

    5. Nisbett, R. E., & Wilson, T. D. (1977). The halo effect: Evidence for unconscious alteration of judgments. Journal of Personality and Social Psychology, 35(4), 250–256. https://doi.org/10.1037/0022-3514.35.4.250

    6. Langlois, J. H., Kalakanis, L., Rubenstein, A. J., Larson, A., Hallam, M., & Smoot, M. (2000). Maxims or myths of beauty? A meta-analytic and theoretical review. Psychological Bulletin, 126(3), 390–423. https://doi.org/10.1037/0033-2909.126.3.390

    7. Klein, R. A., Ratliff, K. A., Vianello, M., Adams, R. B., Jr., Bahník, Š., Bernstein, M. J., Bocian, K., Brandt, M. J., et al. (2014). Investigating variation in replicability: A "Many Labs" replication project. Social Psychology, 45(3), 142–152. https://doi.org/10.1027/1864-9335/a000178