Create with Context did some research recently into how people use the iPhone, with the sample including both experienced and novice users. They’ve released their presentation slides which I found very interesting because they have a bunch of insights that you can apply in your own interface design, not just for the iPhone. Here’s a list of their main findings:
- Take advantage of learned behaviors. "Oh, this works just like the calendar"
- Avoid interaction inconsistencies. "This is weird, cancel is usually over there"
- Provide clear conceptual link across widgets. "This button must be related to that box, they're next to each other"
- Put space between action widgets. "Oh man, I didn't mean to send that SMS!"
- Plan for accidental overswiping. "I keep accidentally changing to a different screen"
- Don't rely exclusively on multi-touch. "It's hard to do this while I'm holding something in the other hand"
- Provide visual feedback for taps. "Did I hit that button? I'm not sure"
- Provide interaction affordances. "It's obvious that you're supposed to swipe left-and-right"
Check out the full presentation slides here.