What if I told you that even the colours that we see are made up by our brain? Just look at this short video made by the Brain Games crew at National Geographic Channel and see it yourself:
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Our perception is kind of tricky: we often reconstruct the information gathered. There are certain distortions that are logical: we tend to filter and re-interpret information according to our needs and/or expectations. Some distortions (like the one in the experiment above) are purely biological: there is a certain capacity of our senses, and when for example the colour receptors in our eyes get tired, they simply "take a break". Also, the information already stored in our brain tends to distort the "facts" we perceive, just look at this short episode from the movie "Interstate 60" to see what I am talking about:
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So what you see is often what you want to see... beware of your judgements! LOL