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- Registered: 18-Nov-2017
- Posts: 67
If by exponential you mean log, then that would be consistent with Fitts' Law. I have used Fitts' Law in my keyboard effort grid calculation. But if doing that, I would definitely suggest accounting for sideways and vertical movements separately, because small vertical movements are simple finger curling motions but sideways movements require whole hand.
I took another look at your page, and then at Wiki for Fitts. I had looked at him before quite a while back, but Den was doing the fiddling with the scoring so I didn't look too deeply.
Log2 is curious ... (my guides in my Giza investigations had me looking for log2 based things there ... didn't find much yet).
It kinda implies the opposite of the "squares" relationship mentioned above.
Regarding horizontal movement ... I always had a problem with Den's penalties on that. I could make a case for the index being able to move 1u sideways, and similarly for the pinky, without the hand having to move. More than that (eg QWERTY J to Y) is a problem.
At the same time, while it is easier to curt a finger, ANSI angle means you can NOT (well, I can't) just curl your index and easily be in or close to the centre of the key below. Middle fingers are worse.
So I think the DIRECTION of finger movement is also a factor. Or consider the attached... how do you type on bottom row without moving everything off Home?
Maybe we need another metric: "hitting this key requires the average person to move their hand x cm, and the penalty for that is ..."