very interesting!

what is a good source of  information regarding this kinds of illusion? is it http://en.wikipedia.org/wiki/Illusion ?

i need to understand why the human brains works that way?
as in why did i find the AC a straight line i mean :)

it is because of my prior knowledge in life (looking at physics phenomena of refractive index of glass)?

by the way, there is an optical illusion that i could not believe.
very interesting too
http://en.wikipedia.org/wiki/Same_color_illusion
[img]http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Grey_square_optical_illusion.PNG/360px-Grey_square_optical_illusion.PNG[/img]
Areas of the image A and B are the same color.

[img]http://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Same_color_illusion_proof2.png/360px-Same_color_illusion_proof2.png[/img]
A rectangle of the same color has been drawn connecting the two areas of the image