Documenting what happens, a little.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Updated with additional simulations.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Some comment tweaking.  It may be a while before I am back to this.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>