Social norms are persuasive, but what if a behavior isn't popular?

For example, in the United States, less than 15% of people eat enough fruits and vegetables. Mentioning this small percentage will discourage people from eating fruits and vegetables because it points the social norm in the wrong direction.

A new technique — the uptrend effect — solves this hurdle. Simply mention the relative increase in people following a behavior (Costello, Garvey, Germann, & Wilkie, 2023).

Researchers offered free apples at an outdoor event.

Some participants saw a sign that said: "...the number of Americans eating enough fruit (2 servings/day) has been increasing over time!”

And it worked. People were more likely to take the fruit.

They replicated this effect across 7 studies, including a Facebook ad campaign.

Why does it work? Because people equate a growing trajectory with a large absolute size, even if the true size is small (e.g., 15% of people).

• Costello, J. P., Garvey, A. M., Germann, F., & Wilkie, J. E. (2023). EXPRESS: The Uptrend Effect: Encouraging Healthy Behaviors Through Greater Inferred Normativity. Journal of Marketing Research, 00222437231167832.