In this technique the right hand thumb (left for left-handed) is supposed to “pick” the string in both direction down and up. In traditional slap technique, the thumb hits the strings with only one movement (down), bouncing to load next stroke and the wrist is the fulcrum. Using double thumbing, introduced by Larry Graham and developed by Victor Wooten, we can, on the contrary, not bouncing but using an opposite motion to produce another sound (up).