The Flash 9.0.0 plugin or higher is required to view content on this page, but was not detected on your browser.
My idea is that a person as s/he moves around the mouse, moves around four mouse pointers simultaneously and thus moves the mouse around less and has it therefore easier and is therefore less receptive to RSI.
The pointers move at the same time, in the same direction and at the same speed.
Imagine four 'squares' dividing up the screen. And each pointer is centered as it is placed in the center of such a 'square'.
Now which pointer is active? The latest direction of the pointers determines that.
Happy pointing and clicking!