While catching up on Twitter this morning I came across a blog post by David Cushman on the simplicity of riding a bicycle compared to using ebay or iTunes.
I kinda see what he's saying, but as he points out I think it has more to do with what people are used to. His daughter has almost certainly seen people riding bikes so I would suggest she picked up the general idea through observation rather than it being particularly intuitive. While it's not likely to happen I'd love to see how someone who's never seen a bike would go about working out how to ride it.
On the most basic level there is also a fundamental difference in complexity between riding a bike and using things like ebay and iTunes, but I'm certain that if someone new to them were to watch someone else use them for a short period of time they'll pick it up quickly enough.
On his point about successful copies needing to work in the same way as existing products I agree to a certain extent, but mainly from a commercial point of view. It's pretty safe to say that the user-friendliness of any product can be improved, but radical departures from well-known interaction are very difficult to sell so improvements tend to be incremental.
I personally think that designing great user experiences in the digital world is harder than it is in the physical world, but purely because it's a new world to the vast majority of people. In the digital world I think one of the main problems is that most systems (both hardware and software) are designed by technical people who are far more interested in solving the technical problems than concerning themselves with the user experience. I get the impression this is changing slowly but I wouldn't hold my breath.
For me the key thing to do when designing a software feature is to forget as much of what you know about software as possible and approach the problem as if you rarely go near a computer. The other day my mother managed to accidentally lock her Vista laptop (presumably with WinKey+L) and the screen it presented her with was one she'd never seen before so she started to panic thinking she'd lost a whole load of work. While this accidental locking may be an edge case for a developer it's one that I'm sure more than a few people have triggered and paniced over. A little more thought about how the locked screen looks could have eased the panic without compromising the purpose of the feature.
Unless you're developing an IDE or other development related software just remember.... you are not your user. Keep that in mind at all times and it will hopefully make you think about what reaction a particular interface will evoke in the average housewife. Will it scare them? Is it similar to something they've seen before? Is it overly scary (big yellow triangles containing black exclamation marks for example)?
Does anyone else have tips for developing software and websites for "everyone else"?