transcript: Our perception of the world around us is
strongly linked to our vision. But how do you know what you're seeing
is real? Can you really trust your eyes? Take for example these two grey
rectangular columns, both of which are different shades of
grey. Or are they? It turns out that they're the exact same. And yet, even after knowing the illusion is there your eyes refused to see them as the
same. Introducing colors produces the same result. I promise no trick photography or
editing effects have been applied. In fact, if you look up the Munker-White
illusion, you'll come across many more examples. Examine them in Photoshop and you can
see that the colors are the exact same. A similar effect can be seen with this
checkerboard illusion. Tile A clearly seems darker than tile B.
But you know better by now, right? Even though your eyes can't see it, you
know when I removed the surrounding imagery the tiles will be the same color. So
what's going on here? The truth is that scientists don't fully
understand this phenomenon, and there are many complex biological
and neurological factors taking place. Ultimately, our brains judge color and
brightness in context. In other words, our brains compare the
surrounding environment in order to create our perception. The purpose of our senses or eyes in this case, is not to provide us with an absolute
color or physical property of our external reality, but to interpret what we see as
efficiently as possible in order to interact with the
environment most appropriately. The tile illusion takes advantage of this
phenomenon. Our brains know that shadows make
objects look darker, as a result the brain compensates by
interpreting the tile as being lighter than it appears until we take the shadow away. Perhaps, the most blatant example is this gradient. The middle bar is simply one color. Remove the background gradient and it
becomes obvious. Once again, the darkness of the background has
affected our perception of the bar's color. Our perception is relative. So do you still trust your eyes? Got a burning question you want answered? Ask it in the comments, or on Facebook and Twitter and subscribe for more weekly science
videos.
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