Watch the Teja's online guitar lesson by TrueFire from 50 Licks Greatest Hits Vol. 1
This is one of the coolest little moves, I never get tired of playing it or hearing it. I first heard it from Eric Johnson as many of us did I believe, then after hearing more Austin based players it seems it's in the water down there. The 3rd of a chord is really the most important, it tells us if the chord is major or minor. In the blues, we want the sound in between those two. Not quite the flat 3rd not quite the natural 3rd. That ambiguity is at the core of the blues. Here we are playing the b3rd and bending it up slightly almost to the natural 3rd while laying on the root an octave below.