Your brain is a great modeler, but sometimes it gets confused. When lighting, shading, or movement combine in just the right way, mental models break down and produce an optical illusion. Showing you this break down is the whole point of OK Go’s latest music video “The Writing’s On The Wall.” Take a look:

I called the brain a modeler because what we perceive as the world around us is our brain’s best guess at the inputs it gets from the real world. Of course the light reflecting off the screen in front of you is really hitting your eyes, but the brain has to then interpret that information before you “see” anything. If you mess with the underlying assumptions of those interpretations, you can distort your final perception of the world. For example, take a look at the two blocks below:

Two differently colored blocks, appearing somewhat in 3D, sitting on top of each other right? Now, cover the separating line between the two blocks so that it looks like there is only one block. Suddenly, your brain interprets the blocks as the same exact color, and they always were!

Why the dramatic difference? In short, the human brain evolved under certain lighting conditions. In our ancestor’s early history, the only light source was the Sun, and it always remained above them. This lighting scheme illuminated things in a certain way, and we evolved to recognize and interpret that scheme. Mess with this basic lighting model and the brain makes an assumption about the colors you see, actually changing your perceptions!

This modeling “software” in the brain is so absolute that even when you know how the illusion works, you simply cannot avoid making the same mistake.

Being able to see just what causes our brain to make a mistake is why OK Go’s new video is so fun. Not only do they produce a ton of illusions (some not actual optical illusions in the strict sense), they do it by showing and then breaking each one, and all in a single take. (You can see an exclusive behind the scenes look at their process here.)

Optical illusions aren’t the only brain breakers. Auditory illusions can be downright bizarre too, and are the reason why those “bad lip-syncing” videos are so darn funny. Who knows, considering that one of their last videos was one giant Rube Goldberg machine, maybe OK Go is working on a full song illusion right now…

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Kyle Hill is the Chief Science Officer of the Nerdist enterprise. Follow the geekery on Twitter @Sci_Phile.

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