Nudge

A behavioral intervention that steers people toward a desired action by changing the way choices are presented, without relying on mandates or financial incentives. Systematized by Richard Thaler and Cass Sunstein in their 2008 book Nudge, the concept became the primary vehicle for applying behavioral economics to public policy and marketing. Common forms include changing defaults, social norm messages, and information framing.

A 2021 meta-analysis by Mertens et al. (PNAS) synthesized over 200 studies and estimated nudging’s average effect at Cohen’s d = 0.43. Nudges are a core tool of Choice Architecture, and their effectiveness varies substantially with context and design quality.