First off, I apologize if this isn't the right stackexchange sub-site for asking thsi question. I was torn as to where I should post this question: it could plausibly belong in Biology, User Experience or even Arqade. However, given the root of my question has to do with the "wiring" of the human hand, I elected to post it here.
Let's assume that wrist adduction/abduction is responsible for horizontal movement of the mouse cursor and that finger extension/flexion is responsible for vertical movement of the mouse cursor. (I am, of course, willing to revisit this assumption, if necessary.) Would it be accurate to say that we are "hard-wired" to be capable of higher precision in vertical movement of the mouse cursor than in horizontal movement?
Description of mouse grip:
In making the above assumptions, I assume a fingertip-grip style of the mouse (as opposed to the claw and palm grips). The (corner of the) wrist rests on the table and acts as a pivot for allowing side-to-side motion (i.e., horizontal motion of the mouse cursor). Meanwhile, flexing/extending the fingers allows for pulling/pushing the mouse away from us, (i.e., vertical motion of the cursor). The main (admittedly unscientific) reason behind my hypothesis is that vertical movement of the mouse cursor uses similar finger motions as those used for hand-writing (which is, after all, a highly precise activity).
(I understand that my question makes the assumption that we are capable of more precise movement with certain muscles of our body than we are with others - please let me know if that's a flawed assumption.)
Why do I care about this?:
If my hypothesis is correct, there would be implications on mouse settings (namely, horizontal and vertical DPI*) that are conducive to both high accuracy and speed. The key issue is that if we keep our wrist in place (i.e., no sliding/lifting of our pivot point) - then we're able to move the mouse a greater distance side-to-side (i.e., horizontal motion of cursor) than we're able to move it toward/away from us (i.e., vertical motion of cursor). However, if there is evidence to support my hypothesis, than an appropriate adjustment (which wouldn't result in a loss of accuracy) would be to have a slightly higher vertical DPI than horizontal DPI.
*DPI = dots (i.e., pixels per inch). For example, I have a resolution of 1366x768 (which is in units of dots or pixels) and a 600 dpi mouse, which means that my (physical) mouse needs to be moved ~2.3 inches (1366 divided by 600) in order for the mouse cursor to move the full horizontal distance of my monitor. To put it simply, lower DPI results in higher accuracy but it is preferable for our wrist to remain in-place in the interest of speed.