Nudges

Cover of Nudges, Evidence Review No. 10

Evidence Review No. 10 · 16 pages · 16 sources

Do nudges work?

Some do. Defaults reliably change behaviour: automatic enrolment raised pension participation from 37 to 86 per cent at one company. But published studies overstate the average. Across 126 trials by two government nudge units, covering more than 23 million people, nudges raised take-up by 1.4 percentage points, against 8.7 in academic journals.

What the report found

  1. Some nudges are powerful. When a US company enrolled new staff in its pension plan automatically, participation rose from 37 per cent to 86 per cent.
  2. Published studies overstate the average. In journals, nudges raised take-up by 8.7 percentage points on average. Across 126 trials run by two government nudge units, covering more than 23 million people, the average was 1.4 points.
  3. Reviews disagree on the overall effect. One review of more than 200 studies found a small to medium average effect; after correcting for publication bias, another found no clear evidence of an overall effect.
  4. Defaults are the strongest. Changes to the structure of a decision, such as defaults, worked better than information or reminders.
  5. Experts cannot tell in advance which will work. In a test of 54 programmes to get gym members to exercise, scientists and others found it hard to predict the winners.

What is inside

  1. The idea and where it came from
  2. The original studies, explained
  3. What happened when others tested it
  4. Where researchers disagree
  5. What we can say with confidence

Plus a timeline of two decades of nudge research and a graded list of claims.

Who it is for

For policymakers, nudge units, marketers, product teams and anyone who has quoted a nudge success story.

How we work

Evidence Reviews follow one well known idea from its origin to today. Every claim is graded Established, Emerging or Untested. Where researchers disagree, as they do sharply on the average effect of nudges, both sides are set out before we say where we stand.

Cite this report

The Why We Project (2026) Nudges: What the large reviews of the evidence say. Evidence Review No. 10. Dubai: Why We Tech Ltd. Available at: thewhyweproject.com