Norman Door—Design Problems
Don Norman, author of The Design of Everyday Things, believes there are two critical pieces of a design: discoverability and feedback. With poor discoverability or feedback, we've failed the people that are ultimately using what we're creating.
I recently came across a great Vox Media video that will haunt you once you watch it. It's crushing because you will start to see these design problems with objects/interfaces that you use every day. If we can start to think through both cognition (how we understand the world) and emotion (how we interpret the world) we'll start to see fresh solutions to past problems.
You can watch the full talk here.