Cialdini argues there are two different norms at work: an “injunctive norm,” or the idea of what people should do (the “ought” norm), and a “descriptive norm,” or what people actually do (the “is” norm). While injunctive norms can have an impact, it was the descriptive norm that was clearly guiding behavior here: People littered if it seemed like most other people did. If only one person was seen littering in a clean garage, people were less likely to litter—perhaps because the other’s act was so clearly violating the injunctive norm.
