lower luminosity = appears farther
that is true in most dark environments and in interior scenes. In outdoors, the oposite tends to happen. maynly in landscapes, objects tend to apear blue, because of the "sfumatto" effect.
of corse in such small objects or characters, you gotta reside on shadows to simulate depth. and darkening the back limbs would make it apear that they are in the shade, from the body, thus making you brain percieve that they are behind.
Kaz