How easily can ones brain be fooled?

How easily can ones brain be fooled? It turns out that pretty easily (at least when it comes to recognizing colors, distances etc...). Look at the two squares marked A and B and compare their color.





Square A seems significantly darker, doesn't it? It turns out, both are the same color... I think the perceived color difference is even bigger in the second case: Compare the color of the little squares that are in the middle of sides of the cube. (I marked these squares with a little tick).



The one on the upper side is dark brown, the other one is orange! There seems to be no question about that. Again, both have the exact same dark brown color. Here are the relevant squares (everything around them was deleted).





The question is, can our brain be fooled so easily in different situations? For instance when one assesses probabilities and uncertainty. I think so (I would recommend the Kahneman, Tversky:Judgement Under Uncertainty: Heuristics and Biases).
The real question is whether the "enlighten" policy maker can do anything about it (maybe he suffers from the same bias-VS comment about casinos banning Martingale strategy players on prev. post) and whether he should do anything about it (maybe people are perfectly happy thinking that the little square is orange rather than brown)...