In something as fundamental to our everyday living as a door, you might think that we had nailed their design sufficiently not to misuse them. However, I'm willing to bet that, like me, you have pulled a door when you needed to push it. A common culprit is adding a bar handle to a door on the side you need to push. While a flat plate attached to the door affords only pushing, a bar handle begs you to pull it. Often, a door designed this way gets a sign saying "Push." As Don Norman says, if your design needs a label, consider another design.

The Design of Everyday Things, Don Norman, 9780262525671
Le design des objets du quotidien, Don Norman 9782212678833

via LHV