Kinda both, would be my guess. The brain reconstructs depth from visual information, so where the visual edge can be interpreted as a depth cue, you're faking

Kinda both, would be my guess. The brain reconstructs depth from visual information, so where the visual edge can be interpreted as a depth cue, you're faking out that mechanism. It also explains why the pure edge detection image just looks noisy, especially in the hair: most of the edges are effectively incidental colour shifts that don't provide depth information.