Defaults strongly influence choices, because many people accept the preselected outcome rather than actively switching.
Johnson and Goldstein's 2003 online experiment found about 42% donor consent under opt-in against 82% under opt-out. Their much-quoted cross-country figures were effective consent rates rather than a controlled estimate of actual donation, so the experiment carries the causal weight.
In practice
- A pension scheme with automatic enrolment reaches 90% participation; the identical scheme requiring a form reaches a quarter of that.
- A cookie banner where "accept all" is one click and refusal is four determines what most visitors choose.
- Possible explanations
- One explanation is effort, since switching costs attention. Another is implied endorsement, as people read the preselected option as advice. A third is loss aversion, with the default acting as the reference point.
- In its favour
- The experimental evidence is strong and replicates across domains, including pension enrolment, where automatic entry raises participation sharply.
- Against it
- The cross-country organ donation figures usually quoted are effective consent rates rather than a controlled estimate, and actual donation depends on family consent and hospital infrastructure, so defaults do less than the headline suggests.
- Standing
- The experimental evidence is strong; the much-quoted cross-country organ-donation figures are effective consent rates, not a controlled estimate.
- Further reading
- Wikipedia
- Subject
- Decision-making & Reasoning
- Essay
- The catalogue of predictable errors