I keep having this argument with family who keep trying to get my grandmother to move to a smart-phone or tablet.
It's the whole mental model of mapping down all the various functionality that makes this impossible for her.
Just some of the issues that we encountered:
- Holding this small thin device means touching at least part of the glass front. This registers as a touch, and/or activates some kind of other unintended functionality when shifting grips.
- Inconsistent UI - things appear and disappear depending on context. 'Pull down from the top/bottom/etc' just makes no sense.
- Inconsistent response times - a variety of applications require polling some server on the internet, which means waiting for dodgy wifi on crummy DSL to then connect to a server that's the best part of 16,000KM away (Sydney to US-East coast). Too many app developers test only against a server that's either on their machine, or on some close-by staging environment and never bother to see how their app responds (or doesn't) on anything less than an ideal connection.
- Single tap vs long tap vs double tap... They all do different things, and because not every application responds at a consistent rate, she gets frustrated and presses it again, harder (not knowing if it just failed to register the previous touch). Worse, because some apps now 'play' the second tap once the new screen has finished rendering ... well we've now clicked in some other random part of the application.
- Often things are delivered as webpages (or partly so) - and again, with content being loaded asynchronously, the page jumps around, often for quite a while.
- Two fingers pressing against the screen / palm rejection... she'll be tapping with the pointer finger, but the knuckles of another finger, or the palm or wrist will touch the screen... causing all sorts of bizzare behavior. Leads to frustration, leads to tapping repeatedly, see above.
Then there's the issue that every 12-18 months, the UI changes, functionality moves, changes, etc.
At least with some devices, you have a home button that's easily locatable, but then that seems to be dying in favour of soft buttons everywhere too, which means that it's yet another thing that you just have to know it's there, and when it's not.
All these smart devices that only have a touch-screen are a major usability problem.