Applications
Make system behavior match user expectations rather than forcing users to learn arbitrary rules. When designing anything people interact with, start by understanding what mental models they already have. Fight the urge to design for how you think things should work—design for how users already think they work. Every deviation from expected behavior creates friction.
Provide clear conceptual models through metaphor and consistent mapping. If your system operates on principles users understand from other domains, make those analogies explicit. Desktop metaphors work because people understand physical desktops. When you must introduce new concepts, invest heavily in teaching the right mental model rather than assuming users will figure it out.
Design for error as the default, not edge case. Build in confirmations, undo capabilities, and clear feedback. Make destructive actions hard to trigger accidentally. Create systems where errors are easily detected, have minimal consequences, and can be reversed. This philosophy transforms user experience from anxiety about mistakes to confidence in experimentation.
Test your designs with people who don't share your mental model. Designers suffer from the curse of knowledge—you can't unsee how the system works internally. The only way to know if your conceptual model is clear is watching people who don't have your expertise try to use what you've built. Their confusion reveals where your model fails.