Anti-litter Behavior Spurred by Modeling

I'm trying to find a specific study illustrating that motivation alone does not yield behavioral buy-in. As I recall, community members self-selected to attend a public lecture on conservation/neatness. Upon exit, they found parking lot strewn with litter. Despite their interest/concern/motivation, they did not pick up unless behavior was modeled. Also interested in any other study (regardless of subject) demonstrating insufficiency of motivation.

Robert Rowell
educator
United States