object recognition theory
1/2 and 3/4 : one 2d view can be illusion, but if several say the same thing, you got the 3d right
5 : dunno. maybe "are the blocks with which you take the pictures the same blocks as those you can identify once you have the picture figured out ?"
6 : dunno. sthing about visual noise ? or that in a complex environnement we dont necessarily distinguish between all the objects separately ????? this is the most mysterious to me !!
7 : object recognition theory of geons (wiki thanks) which kinda answer question 5 and solve the 1-4 problem (property of the geons)
i like the picture number 5 - whatever the meaning intended was lol :)
Visual depth perception has something to do with it.....
Your conclusion: People should wear more hats? 42?