There's a door on the 10th floor of the Vox Media office I hate so much. I can never remember which way it opens, and I get it wrong every single time. You probably know one of these terror doors too. But it's not our fault. Roman Mars of the podcast 99% Invisible magically arrived in my cellphone to send me on a cross-country journey to find out the incredible story behind this common complaint:

Don Norman's seminal book on design, The Design of Everyday Things, was motivated by the same issue. Published 25 years ago, it remains just as relevant today. Doors shouldn't need instructions like this:

The shape of them, if made well, could guide you through just fine.

When most people complain about something, nothing happens. But Norman is not most people — he's a psychologist and cognitive scientist. So his writing about his complaints is so incredibly thorough that he changed the way design works.

And the "human-centered design" revolution he sparked changed not only how designers work, but also how people in fields like public health work to make the world a better place. This is why Melinda Gates believes human-centered design is one change that could save the world. To find out what all this has to do with crappy doors, watch the video above.