jazz bassists to add depth of tone. Axial pitch-shifting Axial vibrato is produced by moving a stopped (held-down) string with the left hand in a direction parallel to its axis, which increases or reduces the tension on the string and thereby alters the pitch. This type of vibrato is typically used by classical guitarists (see Classical guitar technique), but can be performed on any kind of guitar, and is frequently used on steel string and electric guitars. When a classical guitarist sees the term vibrato written in a score, this is generally the first effect that comes to mind. Radial pitch-shifting (string bending) Radial pitch-shifting (also referred to as "string bending" or "bending") is produced by moving the stopped (held-down) string with the fretting hand in a direction perpendicular to its axis and parallel to the frets. This type of pitch-shifting is associated with blues, rock, country and pop music. The effect generally shifts the pitch over a wider range than axial pitch-shifting. It can produce vibrato as a cyclic variation in pitch, a single up-and-down swoop, or as a shift from one pitch to another that is then held. If the strings and action of the guitar are light enough, a player can bend notes by a semitone or more—so string bending can be a way of making a portamento transition between notes, and not just as a decoration on a note. String bends are one of the few ways to achieve microtonality, especially blue notes, on the guitar. Basic technique To produce a bend, the guitarist puts a finger on the string and then, while pressing the string down to the fingerboard, strikes a tone, and pushes or pulls the string to the side. This has the effect of stretching the string and thus makes its pitch higher. Generally a bend on the lower (6th–4th) strings moves them down vertically, as seen from the guitarist's point of view, and a bend on the higher (3rd–1st) strings moves them up. The technique can also be used with pinch harmonics. A backward, reverse or release bend involves pressing the string to the fingerboard, pulling or pushing it up to stretch the string first, then striking the string and relaxing the string to normal position. This causes the note to go flat, the reverse direction of straight bend. Sometimes a guitarist bends a note on a certain string up, while playing