While the height of finger lift and drop depends on tempo and musical context, some general principles are useful for good articulation.
In this lift-and-drop exercise you lift the 2nd finger up as far as the nail joint of the 1st finger (which is held down on the string). Repeat with the 3rd finger, lifting it to the nail joint of the 2nd finger.
To help develop the 4th finger action, lift it higher, that is as far as halfway between the nail joint and the middle joint of the 3rd finger.
Resources - Bibliography
- for The Art of Tone Production by Sherman Pitluck, p.7