If you've ever heard a keyboard player using a guitar patch so well that you really thought it was a guitar being played, know that part of the trick is voicing chords as a guitarist would. Electric bassists often learn to develop walking lines without using open strings frequently, unless in the lower positions.

The leaps and arpeggios used by upright players often include open strings, even when the player is playing far up the neck. By using this technique, the electric player will "voice" lines as an upright player does, making for a more authentic sound.

Note example 1. This walking line overdoes the technique; in most situations you wouldn't want to use this device as much as it is used here over an F Blues.