For more detail (and to correct my previous post a bit), in materials with low electron mobility (aka insulators), what happens isn't so much the movement of ch

For more detail (and to correct my previous post a bit), in materials with low electron mobility (aka insulators), what happens isn't so much the movement of charge carriers, but rather the orientation of each atom's electron field. Basically, by imposing a strong gradient, it will cause each individual atom's electron cloud to reorient/shift, which causes each atom to set up it's own little gradient which points in the opposite direction. You sum up those little reorientations amongst all particles in the material, and you end up with a net electric field that points in the opposite direction, which then becomes attractive. The above is a bit more accurate description of what happens in insulators (which accurately models some parts of our skin), while a-priori's description fits the conductor parts (most of the wet bits) of the human finger better. And obviously, this is just an approximation/model of what's going on.