I actually adapted to most of the day to day optical illusions, because i have seen them numerous times before.
Seriously, most of the optical illusions i see are not fooling my brain at all!!!
If you dont see a straight hand, that means you have vision problems!!!
Follow the paths of the lines using your hand, you can see this is actually straight.
Actually, these lines are straight.
ID:2088642 here is proof of my statement. the lines should appear somewhat straighter. (they will still look a little like they're zig-zagging between each individual square, but that's because the mix tool doesn't blur as well as the deco tool would.
the only way to see straight lines in this illusion is to have imperfect vision. blurring the edges of the shapes will break down the sharp corners and straight edges that confuse your brain into imagining perspective and allow you to see the image as it really is. TL;DR if you see straight lines you need glasses.
Shywha: While I cannot judge Szymciu's statement, other than being disrespectful, I have to disagree with yours. I myself used to see this illusion, but it stopped after I saw it often enough. I cannot precisely describe how I do it, but I can make myself see the lines straight.