Why is it, in the study by Cialdini and his colleagues (1990), that a single piece of trash is more effective at reducing litter than a perfectly clean landscape?

Question

Quizplus · Accepted Answer

The presence of a single piece of trash in an otherwise clean area creates a contrast effect that draws attention to the act of littering and reminds people of the norm against it. This contrasts with an area that is already littered, where the presence of additional trash may simply blend in and not be as noticeable.

Why Is It, in the Study by Cialdini and His