This is just my personal experience with my first capacitive touch mobile device, a Samsung Galaxy Nexus GT-i9250, in response to Ben’s article I hold my phone with hand X, then tap with hand Y.
I’m not trying to point out any flaws in Ben’s survey or diagrams, but just wanted to add my 2 cents. I use my device single-handed most of the time, with my right hand.
This diagram illustrates my personal analysis of the ease of access and interaction with the screen divided into tap zones, like in Ben’s article:
I don’t know if the additional strain of tapping close into the right corner near my grip or on the lower left is due to my wrist injury (for those who don’t know, I fell off a cliff about 10 years ago and am lucky to be alive) or if that’s something other people experience.
Upper-left corner is virtually impossible and requires an awkward shift in grip to reach or resorting to two-handed. My hand is 19cm long.
What do you feel are the hard-to-reach or awkward regions of your mobile device to interact with? Do you ever type on the soft keyboard single-handed?
Microsoft’s Windows 8 design guidance includes a section on common grips/postures for tablets; what are your thoughts on tablet tap zones?