We love a good optical illusion, and this one shows just how much our brains can be fooled when it comes to distinguishing colour – and how doggedly we cling on to our initial belief about what we're seeing. Created by Japanese psychology professor Akiyoshi Kitaoka, the image shows six squares on a rectangle that grades left to right from orange to yellow.
Chances are that you'll see the squares on the right are a darker shade of orange than those on the left. But your brain's been tricked. Placing the squares on a white background – or indeed checking the RGB values in a programme like Photoshop – shows that they're all exactly the same. (See our guide to how to download Photoshop if you need the software.)
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Are the six squares different shades of orange? Click right for a different perspective(Image credit: Akiyoshi Kitaoka)
Here are those six squares again, but on a white background(Image credit: Akiyoshi Kitaoka/Future)
The optical illusion appears to work because of our tendency to judge the colour and brightness of an object by comparison with the other colours or lighting that surround it. You can learn more about this in our guide to colour theory.
Kitaoka has made the short video below, demonstrating just how powerful the illusion is. In the video, he moves one of the coloured squares from left to right across the rectangle. The square appears to change colour and brightness as they move across the background.
Of course, the square has a horizontal gradient, from dark orange on the left to lighter orange on the right. This helps to trick our eyes since a solid shaded colour would be easier to distinguish against the background. The square is also cut from the very centre of the rectangle background, which is why it seems to disappear when it reaches the centre – another factor that makes it more difficult for the brain to correctly interpret what's happening.
