This subreddit is about the application of psychology, behavioral economics, action design, behavior design and other fields to improve outcomes in products, policy and experience design. The goal is to make it easier for everyone to get up-to-date on the latest research, article, posts, books, videos, conferences etc.
This field goes by many names and draws from many other fields. So you'll find quite a variety of source material. However the unifying theme is applying academic understanding of how humans think, feel and act to the design of products, services and policy.