14 · Deciding
Cognitive Bias
Everyone takes mental shortcuts. They're fast, and they're often wrong.
Evidence: Holds, with limitsWhat we do with it
- 01
People skim for what they already believe. Put the fact that might change their mind where they'll see it.
- 02
Defaults carry a lot of weight. Most people keep whatever is already selected, so pick defaults that serve them.
- 03
Your team has shortcuts too, and knowing about them doesn't switch them off. Read your numbers looking for what would prove the design wrong, and test with people who didn't build it.
- 04
We never use these shortcuts against people. No decoy prices, no guilt-trip buttons, no add-ons ticked in advance.
Examples
Getting it wrong, getting it right.
Don't
A checkout with insurance ticked in advance, so people pay for it without deciding to.
Do
Insurance offered, unticked, with the price shown. The default is the choice most people would make for themselves.
Don't
A crossed-out “was” price that was never charged, put there to anchor.
Do
One honest price. If there's a discount, it's off a price people actually paid.
The evidence
What the research says.
Psychology's replication projects sorted these out. Some held up firmly: anchoring repeated across 36 separate samples in the 2014 Many Labs project, and a 2019 meta-analysis of 58 studies found defaults have a medium-to-large effect on what people choose (d = 0.68), though it varies a lot from study to study. Other famous results, especially subtle priming effects, didn't survive.
How our view changed
We design around the biases that held: defaults, anchoring, framing. We're skeptical of any design trick that leans on a single striking study.
Sources
- Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185(4157).
- Klein, R. A., et al. (2014). Investigating variation in replicability: A “Many Labs” replication project. Social Psychology, 45(3).
- Johnson, E. J., & Goldstein, D. (2003). Do defaults save lives? Science, 302(5649).
- Jachimowicz, J. M., Duncan, S., Weber, E. U., & Johnson, E. J. (2019). When and why defaults influence decisions: A meta-analysis of default effects. Behavioural Public Policy, 3(2).
Last reviewed November 7, 2026. How we keep this current