Case Study

How Social Proof Can Drive Action


95% of Americans support organ donation. However, only 48% of Americans are registered organ donors. What can we do to get more Americans to register as organ donors?


We partnered with a company to test whether adding social proof messaging of the injunctive norm (what people think should be done) affects registration rate among their employees. In the control condition, subjects received an email asking them to register as an organ donor. In the treatment condition, subjects received an email with the same language, with an added line mentioning that 95% of Americans support organ donation.


We found that those in the treatment condition were almost four times more likely to register for organ donation than those in the control condition.

Why it matters

Social proof messaging can be an extremely powerful tool, even for important decisions such as whether to become an organ donor or not. This study demonstrated that injunctive norms can work as social proof messaging, which stands in contrast to the more common use of descriptive norms. This study revealed a useful technique to motivate people to not just think something is good to do, but actually take related action.