Full transcript of experimental psychologist Daniel Simons’ TEDx Talk: Seeing The World as It Isn’t at TEDxUIUC conference.
Daniel Simons – Psychologist
I’d like you to take a look around you, take in all the sights, the sounds, if you’re unlucky, the smells. You feel like you’re seeing the world in all its completeness and detail, you feel like you’re experiencing the world as it is. But that experience, as it turns out, is an illusion. What you actually experience is what your mind and your brain give you, it’s an alternate reality.
Take a look at this image. This is by Julian Beever who is a British artist. Now, this is an illusion, this is a nice painting of a swimming pool, it looks like it has depth, looks like there’s a woman sitting in the pool, looks like Julian Beever up on the upper right is dipping his foot into the pool. And as he’s doing this, you feel like you are seeing the world as it is. But of course, it’s not, it’s chalk-art on a sidewalk, it just gives the impression of depth. And this is a double illusion. Because as you’re looking at this, you feel like, “Okay, yes, I’m seeing a painting of chalk-art on a sidewalk.”
But what you’re actually seeing is a really weird view of a chalk painting on a sidewalk. You’re seeing a chalk painting on a sidewalk from the one view that gives you the impression of depth, that gives you the impression that you’re looking at a swimming pool. And from any other perspective it looks much more like this. It’s really substantially distorted. The key is that we feel that we’re seeing it as it is, but we’re actually not.
Let me give you another example: this is from my colleague Burt Anderson. What you see here are two sets of chess pieces; the ones on the top look dark, the ones of the bottom look light — I’m sorry, the ones on the top look light, the ones on the bottom look dark. And you can’t help but see them that way even though that’s not at all what you’re actually seeing.
Here is what you’re actually seeing: I’m just removing the background, and when I remove the background, you can see that both sets of pieces are the same kind of mottled gray, and every piece on the top is exactly the same as the one directly below it. Now that you know that, of course, you’ll be able to see them as they are, when I show you the same image again, right? Nope.
Once you go back to the background you can’t help but see it as it isn’t. Your visual system is giving you the impression that you’re seeing light pieces and dark pieces when you’re actually seeing the same thing in both cases. What’s happening here is that your visual system is taking into account not just the brightness of those individual pieces, but the brightness of the surfaces immediately around those pieces. And it takes that into account in a way that’s actually really useful for us most of the time. It gives us the ability to see a piece of paper with black ink on it, the same inside in a dark room and outside in a really bright light. But it’s not giving us the world exactly as it is it’s using a bag of tricks, it’s using a set of shortcuts, to give us the world as we need it.
Now, what makes visual illusions like this so cool? Well, there are two reasons. One is that it’s surprising, but that’s not terribly satisfying, the more interesting reason is that it’s giving us the impression that we’re seeing the world as it is. And it’s violating that impression, it’s breaking our intuition, it’s forcing us to confront the fact that we aren’t seeing the world as it actually is.
I’ll give you another example of this: this is from Bill Geisler and Jeffrey Perry. This is a nice picture of flowers — pleasant for today. And I’ll show you a bee, and I want you to follow that bee around this image with your eyes, so track the bee as it moves through the image. It’s supposed to kind of wonder around the image here, and you’re able to follow it just fine, and eventually it’s going to end up back where it started. And, we’re back.
OK, now I want to show you exactly the same sequence, except, this time, instead of tracking that bee with your eyes, I want you to maintain your focus, maintain your gaze right on the bright yellow flower. And notice what happens to that flower as the bee gets farther and farther away; it gets blurrier and blurrier. It’s exactly the same sequence, you’re seeing exactly the same thing you did the first time, except that this time you probably noticed that it’s getting blurry, whereas the first time you didn’t notice that anything was changing about the image at all. Why is that? The reason is that you’re actually only taking in detail from a tiny, tiny subset of your visual world at any instant. In fact, you’re taking in detail from a subset about the size of that bee. You’re taking in, if you stick your arm out and put your thumb up, you´re taking in high resolution information only from the information about the width of your thumb. Beyond that, it becomes progressively blurrier, but we don’t notice this at all.