Thursday, November 26, 2009

Look again!

Over the past couple of weeks, Matt and Morgan have upped the anti with blog posts with pretty pictures. Matt shared some of his visit with a couple of stars of psychology, while Morgan gave us a nice summary of a well established illusion. So, now I have to try a bit harder. For this post, I want to show everyone one of my favourite visual illusions, and give you a quick run down on how it works.

I think the illusion, below, is the most compelling illusion ever, and you probably wouldn’t even believe what the illusion is without the additional pictures (I certainly wouldn’t). Seemingly, it’s just a swirl of pink, green and blue, right? WRONG! Actually, what seems like green and blue, are exactly the same colour!!!

Now, you probably don’t believe me, so in the version below, I edited in an aqua-coloured bar that is the same colour as both swirls and zoomed in.

So why does this happen? Why would our brain tell us so convincingly that two colours are different when they’re not? Have another close look at the purple and orange spirals that seem to run continuously around - the orange lines stop before the “blue” stripes, while the purple lines stop before the “green” looking stripes. Our brains like to fill in visual information, so at first glance we see the purple and orange loops as continuous. Then, without us realising, our brains contrast the darker colour of purple to the aqua, making it seem greener, and then contrast the the lighter colour of orange to the same aqua, making it seem darker. That is a simplified explanation, but, wow, what an illusion.

I saw this illusion posted in an online forum, one poster said in reply to the picture, "If we all get tricked by the illusion, then we are all seeing the same thing." This is an interesting sentiment - if everyone's brains process the image as being two different colours, does it matter that there is only one colour when we look at it closely? Maybe not, but it's still cool.

This illusion was created by an illusion legend, Akiyoshi. Be sure to check out all of his other very impressive colour illusions here: - you might soon find out that your brain is tricking you more often than you realised!

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