Yeah - I can cross my eyes on command because I clowned around as a kid. And I can actually get "Magic Eye" stuff to kind of work that way, it's just inverted... What I can't do is spread my eyes wider (I think the insensitive term is "go wall eyed") on command. I'm not cross-eyed at rest or anything like that, but the motor skills to widen the distance between my two pupils (The way you would when you're looking at something far away) just isn't well developed.