Sunday, July 29, 2007

Why Are We So Easily Fooled?

Yep... there's a bit of a common theme running through the last few posts, the ease with which the mind can be fooled. Here's another one for you. Take a good look at this image...

The squares marked A & B are the same shade of grey.

Absurd, ridiculous, I hear you say. I thought so too until I checked by opening the image with gpaint (The Linux equivalent of MS Paint, although it's a misnomer to call it an equivalent when its clearly superior).

Yes, this is simply an optical illusion but think about it. If we can be so easily fooled by something so simple, what does that say about other judgements we make in life? A bit too sobering or negative? Perhaps. But the most astounding thing about this is the mind's stubborn refusal to see things as they actually are. Even though I can logically convince myself that these too shades are identical, I can't see it. Try as I may, I can see the shades are the same when they're put next to each other, but as soon as I look up again, B is clearly lighter than A, even though I know it's not.

So why is the mind so easily fooled? I'd like to hear what you think? For my part, I think it comes down to the fact that perception is a mental action, not a function of the eyes. Think back to your high school biology class and how the lens in the eye inverts everything, making everything upside down. The mind then has to process that image, turn it right way up so it reflects reality. So everything we see has been processed to one degree or another. It's all be tampered with subconsciously.

In short, we see what we are supposed to see...


Onyx Stone said...

If we perceived what we literally see with our vision, it would be too hard to make judgements necessary to life. I don't have time to process everything I see. If I did, I couldn't even cross the street.

I have to assume that roads and cars and legs still work the way my internal mental model generalises. A new set of photons hitting my eyeballs as never before may not act the same way as other cars, but I'm counting on the laws of momentum, etc, being the same as all the other cars.

Think of Wayne Rooney kicking a volley into the top right corner at full sprint. All of NASA couldn't describe the physics (the angles, the spin, the wind, the stride, the fatigue) of what Rooney just 'feels' and does in a split-second in the heat of the contest with 80,000 eyes on him.

If we can make assumptions, we can do brilliant things. Most of the time, we are not fooled, we are capable of high-level processing, because we are not constantly re-visiting the low-level processing.

But you are carefully selecting examples where the lower-level processing makes errors. But notice that your last two illusions were 2-D computer generated images, not real life. The human eye-brain combination does better in real life.

"Are you stuck?" asked Rabbit. "No," said Pooh, "I'm just resting and thinking and humming to myself." said...

I don't know that optical illusions are the result of assumptions in the classic sense of the word. You can change your assumptions. The thing with optical illusions is, even though you know they're not accurate, you still see them the wrong way. In other words, the eyes are still "fooled" even though the mind knows different.

Yes, the examples I gave a computer generated. But there are equally valid natural illusions. Have you ever noticed how the moon looks larger when it's lower in the sky, closer to the horizon. It's tempting to think that this is due to some physical reason, like the atmosphere distorting and magnifying the image, but it's not. Take a photo of the moon when it's low on the horizon and when it's at it's zenith and compare them. You'll find they're the same size. It's all in the mind.

In the case of the moon, your eye "enlarges" the view relative to the other items you can see on the horizon. Once the moon is high in the sky, there's no longer a point of reference for the eye to cling to.

Up for a natural test? Take a sheet of paper with a pin prick outside when the full moon is low on the horizon. The moon looks big, right. Look at the moon through the hole in the paper and it looks small. Open both eyes and the effect is even weirder. One eye sees a large moon, the other a small moon.

Bizarre, but there you have it.

Onyx Stone said...

My point is that we make complex judgement quickly by not re-visiting all the lower level judgements.

I can recognise a chess board almost instantly. I don't check the colour of each of the 64 squares. Even if the chess board is partly in shade making the silver squares reflect only as much light as charcoal squares in bright light.

I would say that is a strength. My perception is so sophistocated that a partial shadow doesn't even slow me down in recognision of a chess board!

I understand the expected effect of the cylinder shadow. So I could happily call square A black and square B white. And that's also why your illusion fools me. I'm optimised for the big picture. - the chess board in partial shadow. You're pointing out the actual squares are the same colour without reference to the shadow.

And literally, they are not squares either. Put your protractor on the screen and check! Only our minds are sophisticated enough to interpret squares viewed at an angle and not even trouble us by acknowledging the feat! Pretty smart, huh!

"Are you stuck?" asked Rabbit. "No," said Pooh, "I'm just resting and thinking and humming to myself." said...

It's not that we make complex judgement quickly by not re-visiting all the lower level judgements, it's that we cannot re-visit any of the lower level judgements.

My point is that the brain is hardwired to see things a certain way and, even though we know something mentally to be true, we can't see it.

You know the checkers are the same colour at a conceptual level, but you can't see it in that picture, no matter how hard you try.

The same is true of the moon. You can switch the moon illusion on and off by blocking out the horizon (either with some paper or by making a funnel with your hand and peering through that). But you cannot switch off the illusion mentally. You cannot control the way your mind interprets reality so as to not fall for the illusion. You cannot refocus so the illusion does not exist without some kind of physical intervention (like the paper or your hand).

It's part of the autonomous functions of the mind. Neither of us have any more control over it than we do over our own heart beating. There's indirect control, to a degree, but no direct control at all.

Yes, our eyes allow us to process visual information at a remarkable rate so we can kick a Wayne Rooney goal. But that same process has some fundamental flaws, for all the benefits, there are definite drawbacks.

Ultimately, it's the mind, not the eye, that is playing tricks on us. And I don't think it stops with optical illusions. The same autonomous rapid interpretation of reality comes at us conceptually as well and, if we're not prepared for it, we will fall for mental illusions just as easily as we fall for visual illusions.

I don't profess to understand half of these... but I have seen them at work time and time again and have fallen for plenty myself...

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Lord Trafalgar Rock Pigeon said...

You're on to something here but I have a theory. Just as when we look out of our right eye only, it's inefficient and the same for the left but when we combine different angles, we have stereoscopic, so perhaps the combintion of all the senses would produce a result in every day living approaching efficiency.

Pooh's Corner said...

Good point... for the sake of analysis we often separate out one sense over the other, like sight, but in reality, all the senses work together to allow the brain to interpret the world around it.

How interesting, then, that optical illusions specifically exclude all other senses...

Phil A said...

That is so weird. I just couln't see it - Still cant.

I loaded it into Paint Shop and verified it though - weird!