Any time you see signs or labels added to a device, it is an indication of bad design: a simple lock should not require instructions.

What makes something simple or complex? It's not the number of dials or controls or how many features it has: It is whether the person using the device has a good conceptual model of how it operates.

Also note that invariably when we design something that can be used by those with disabilities, we often make it better for everyone

The hardest part of design ... is keeping features out.

It is not enough that we build products that function, that are understandable and usable, we also need to build products that bring joy and excitement, pleasure and fun, and, yes, beauty to people's lives.

Learning should take place when it is needed, when the learner is interested, not according to some arbitrary, fixed schedule

To me, error analysis is the sweet spot for improvement.