Distinguish what people commonly do from what people approve of.
Limited evidenceSupporting studies exist, but they are few and conditions matter.
Example
Editorial example: explicitly welcome questions instead of emphasizing how few people ask them.
Why it works
Cialdini and colleagues distinguish descriptive and injunctive norms in field experiments on littering, examining which norm becomes salient.
On the web
Give denominators and periods for behavioral facts. Label desired behavior as policy rather than implying it is what most people do.
When it backfires
Littering studies do not directly predict posting rates. Advertising unwanted behavior can communicate the wrong norm.
Sources
Field experiments examine two kinds of norms and the role of their salience in behavior.
Cialdini, R. B., Reno, R. R., & Kallgren, C. A. (1990). A focus theory of normative conduct. JPSP, 58, 1015–1026. Open source