And how about the error of hitting an adjacent key? Sole and Dole for example. Or hitting in the wrong order. I have a friend who cannot type "that" to save her life, it always comes out has "htat". The nature of the QWERTY keyboard and of the T-9 function on the phone seems to set up a curious gravitational relationship between the letters. Erroring between Sole and Dole is more likely it would seem than between Dole and Mole or Sole and Mole. The M is too far away on the keyboard for that type of error to made without a massive mental lapse.
One more example: we often read "/" at the end of a sentence as "?" because the two share the same key, and to switch from the key's shifted option to the non-shifted option is a common typo on a standard qwerty keyboard.
The T-9 Word function on cellphones is just great fun. To see all these different words (sometimes hilariously different) brought into such close relationship with another by the functionings of the system. Good stuff. I'll have to keep an eye on things the next time I send a text message, I'm sure a funny error will pop up. Lately I've been learning how to build swear words out of fragments. For example, I would type 2, 7 to get "as" then space then 7 to get "s" then space and then 4, 6, 5, 3 for "hole". Then I go back and delete all the spaces and voila! I've spelt "asshole".
I really see this as all tying back to the block metaphor. One thing that it may not account for is how the system of use changes the blocks. For example, in the qwerty keyboard system the / and the ? blocks would be very similar to one another. However, for someone handwriting a letter this almost little to no chance the same error would be made. The blocks are thus easily distinquishable. Maybe this is where I interject color to the equation? Perhaps "?" and "/" have very similar shapes, but different colors. When you use the QWERTY sytem, you put on the QWERTY glasses which blend the colors of the "?" and "/" blocks. I'm beginning to sense a breaking down of the Block Metaphor as this seems a little flaccid. Glasses? What am I thinking? Although, maybe this can be reconciled. How do different systems of using the blocks become accounted for in a system where the blocks are assumed to be constant... WAIT! Maybe there's more than one block for the same thing... No, that doesn't work. What says you? What says you, Laquer?