Rubber Edges

I spent some time today playing with the iPhone and there's one interaction I just love. It's that when you scroll to the edge of the web page, the iPhone allows you to drag/scroll as far as you like past the edge. It just lets you stretch right past the edge into the "grayness", but when you do let go it pulls back to the end/edge of the data being displayed. It's like the iPhone is saying, "You're in control, but there's no more data over there. Honest, but if you want to go there, sure, you can. But I'm telling you there's nothing there. See, I told you, nothing there. It really is the end." This is very clever. It gives you both a sense of control, but also a sense of boundary. It's like the difference between a corral with split pole fences and one with electric fences. Both define the boundary, but with one, finding the edge is much more unpleasant.