Designed for Use, 2nd Edition

Behavioral Consistency

Being good at recognizing user interface elements for what they are can cause a bit of a problem for people: they tend to apply their existing mental models liberally. The more a user interface element looks like something users already know, the more they will expect it to work like the thing they already know.

This problem often arises with custom versions of common user interface elements, which you may sometimes need to create. Because people will apply their existing mental models to your custom elements, you need to ensure that these elements behave exactly like the commonly used elements. If you violate their expectations, ...