Push or pull?

  Think of the last time you opened a door in an unfamiliar place. Did you pull? Push? Did you feel like the kid in the cartoon? If a door is not a swing door, you can either try to tell people what to do, or design the door so that the only option available is the right one. If you see a smooth brass plate with nothing to grab on to, the only thing you can do is push. If you see an inviting handle, you will probably pull. People in the know tell me this is called affordance, although I can never remember the word when I need it.

When I picked up an iPod for the first time, I put the earphones in my ears and started looking for a volume control of some kind, a little wheel maybe, or a slider. For a few seconds I was stumped -- nothing I saw looked like a volume control. Accidentally I brushed my thumb across the front of the iPod. The screen lit up and I saw the familiar volume bar. I had a cool feeling of being surprised. I started playing with the scroll wheel to see what else was there. This is a different kind of affordance, it seems. The interface kept you in suspense for a moment by removing the familiar, and then pleasantly surprised you, in a kind of way that made you want to discover more.

As we're rethinking the design of Swivel, this concept is one of the things on our minds. Can you remember situations, in the physical world or on the web, where affordance was just right -- or completely wrong?