19 November 2011

Optical illusion Saturday

I haven't written about optical illusions in ages but a website, Mighty Optical Illusions, popped onto my radar this week and I can't get enough of this guy's site. He has thousands of illusions; visual, audio and video. Check out that site but I have to warn you, it won't be a quick visit.

Click on any of the illusions that follow and they will open in a larger size.

Mighty Optical Illusions is great at not only presenting these illusions, but explaining why and how they work. Here's a great example. Stare at this image for around a half a minute without blinking and it will disappear.

It disappears due to a phenomenon called the Troxler Effect. The Troxler Effect describes visual fatigue. Stimulus that isn't moving eventually disappears from human perception. The Troxler Effect isn't reserved for visual stimulus either. If you take a small piece of paper and set in on your forearm, you'll stop feeling it after the same half a minute, provided neither the paper nor your arm is moving. Pretty slick.

This animated .gif is beyond cool. Let it load and start its animation. Notice the speed of the dots. Then, take your hand, hold it up to your monitor and cover the center of the image. Notice how the dots speed up?

That's an amazing effect and it illustrates very clearly that human brains are utterly dependent on context and previous experiences to make sense of the world.

This one's called Dancing stars. When you get to this illusion, scroll your sceen up and down and the center star field seems to move. Not only that, the sides of the inner square seem to slant a bit, even though they're perfectly straight.

This is the illusion of the running faucets. Stare at this one for a moment or two and the taps will appear to be running.

If you look at this for long enough, it's actually, physically fatiguing. That's from your brain trying desperately to make sense out of this apparent movement.

I love illusions that appear to be animated even though they're not. Here's a really great one.

The illusion of movement is caused by something called saccadic movement. It's an evolutionary adaptation that allows eyes to focus. It's a bit of a paradox, but when an object isn't moving, it fades from view. Having eyes that move back and forth rapidly and involuntarily keeps stationary objects visible.

Speaking of illustrations that appear to be animated even though they're not, check out this one.

That's absolutely amazing.

Again, spend some time over at Mighty Optical Illusions, the guy pulls together some of the most mind-bending stuff I've ever seen.

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