But what about when I cover all 3 borders?

#1. You will see only one color shade only. try it.

#2 don't know about you but i don't have a third arm to hold that extra pencil up to the monitor.

Seriously though #2 is correct and you'll only see one shade of blue.

Here's another similar effect i saw yesterday: http://antwrp.gsfc.nasa.gov/apod/ap091004.html

whats with the thumbs down on #2? It DOES appear to be one sahde of blue if you cover all 3 transitions. (I managed to hold up 2 pencils and just me right hand for the 3rd transition..... improvise dude.)

Wow! i guess the only reason we see the pieces as different shades is by looking at the borders

In the same idea as #5, that's also why we see people from another country as being ''different'' from us... because there's a border!

Try putting the pencil in the middle of the shade, between borders.It looks like sides have different shades.

Or
It's a piece of one colour blue paper with 3 folds.

I paused at 0:20 exactly when the pencil was between the two borders. I took a screenshot and went to paint. It is a lot lighter blue on the right side of the pencil than it is on the left. Try it yourself.

#9 Great work! I think it's safe to say we've rigorously tested this one team.

#7
You are right
The brain follows logic... but not always correct logic
and #8...
I thought that too at first glance ...
Very logical .. just faulty logic