When you look at the blue and yellow lines in the image, are they straight or crooked?
Certain colours are used to confuse our brains, because we are trying to focus on one colour at a time and therefore we see the horizontal lines as crooked, not straight. They seem to narrow distinctly at one end, but if we keep staring at the image for just a few seconds, our brains work out the puzzle and visually adjust the lines. When the vertical lines meet their appropriate colours, it is clear that all the lines in the illusion are straight.
Are these lines straight?
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