Self-determination theory is the most replicated motivational framework in psychology. When I stopped guessing what keeps users engaged and started designing for these three needs, retention stopped being a mystery.
Don Norman's three levels of emotional design—visceral, behavioral, reflective—explain why beautiful, usable, and meaningful are not luxuries. They are how humans actually evaluate things.
Kahneman and colleagues showed that people remember experiences by peaks and endings, not averages. That single finding reshaped how I close projects and onboard clients.
Ebbinghaus discovered in the 1880s that people remember beginnings and endings. Over a century later, most homepages still bury the important things in the middle.
Reaction-time research and uncertainty reduction theory explain why endless menus and vague promises hurt conversion. Here is the framework I use with clients.
Decades of research on working memory and instructional design explain why cluttered sites exhaust visitors. Here is how I apply that evidence when I build products.