Watch the A minor Blues: 1st Chorus online guitar lesson by Robben Ford from Riff Revolution
So for the next four bars, I play an A minor 7 chord. First of all, I'm playing the simplest thing you can possibly play, which is the arpeggio of the chord. But, the first chord that you hear in the rhythm section is D minor. So what I'm playing is a note that alters the D minor chord to a D minor 11. And it's just a pretty sound, as opposed to real strict blues playing.
That was a very deliberate choice to get a lighter, prettier flavor, as we have those possibilities in this progression. I'm opening up the sound of the harmonic palette by playing a very simple idea. These are things I rely on all the time to change the mood and the feel.