Optical Illusion

Sometime I wonder about the difference between what I think we see and what we do see.

I know that these three vans are of exactly the same size (the one at the front and the one at the back are a copy and paste of the one in the middle) but I can't see it :





what do you see ?

(not my illusion).

I see manipulation....and not necessarily all that great. Ha ha, shadows don't line up or reflections are weirdly same, bla bla bla.

FrancoD said:

I know that these three vans are of exactly the same size (the one at the front and the one at the back are a copy and paste of the one in the middle) but I can't see it :

Click to expand...

Yes the three vans are images of the same van however there is no "optical illusion" as the two pasted images have been resized larger and smaller.

It's not as if the van image in the front will exactly overlay the image in the middle nor will the one in the back overlay the one in the middle.

grsnovi said:

FrancoD said:

I know that these three vans are of exactly the same size (the one at the front and the one at the back are a copy and paste of the one in the middle) but I can't see it :

Click to expand...

Yes the three vans are images of the same van however there is no "optical illusion" as the two pasted images have been resized larger and smaller.

It's not as if the van image in the front will exactly overlay the image in the middle nor will the one in the back overlay the one in the middle.

Click to expand...

You are mistaken. Here's a copy of the front van pasted directly over the second van and another copy pasted directly under the third van. They're all the same:



The fact that you thought they're different sizes is what makes it an illusion.

grsnovi said:

FrancoD said:

I know that these three vans are of exactly the same size (the one at the front and the one at the back are a copy and paste of the one in the middle) but I can't see it :

Click to expand...

Yes the three vans are images of the same van however there is no "optical illusion" as the two pasted images have been resized larger and smaller.

It's not as if the van image in the front will exactly overlay the image in the middle nor will the one in the back overlay the one in the middle.

Click to expand...

That is exactly the illusion. They appear to me (and obviously to you...) to be of a different size but they are all three of exactly the same size.

so ,thank you for confirming the illusion.

Leswick II said:

I see manipulation....and not necessarily all that great. Ha ha, shadows don't line up or reflections are weirdly same, bla bla bla.

Click to expand...

that was not the point .

Do those vans look to be of a different size or do they all look to be the same size but at a different distance ?

(in case this is still not clear, get the ruler out and mesure them. You might be surprised. I was and still am).

See the Sybersitizen post for a visual demo.

thats cool, i measured the vans and they are the same size.

NIce one, not seen that before. The way that we see and perceive is most clearly demonstrated in optical illusions, or what happens when you present the eye with information that conflicts with our experience and memory.

It works something like this:

You clearly read the vans as being one behind the other (overlapping) on a road that recedes into the distance (perspective consistent with experience).

Yet they are the same van at exactly the same size. This creates a conflict because it goes against your experience and memory of perspective.

For it to be consistent with your experience and memory then the van must increase in size as it appears to get further away (it can't be the same van at the same size) and this is what your brain sees (not the eye).

For you to believe that your vision is absolute then what you see around you must remain consistent because if it varied then you would question what you see.

So in situations where you have information that conflicts with your memory then the brain modifies that information to remove that conflict and preserve our belief that our vision is absolute. The belief or trust that what we see is absolute and true is more important to our survival than an eye that has absolute vision simply because we need that consistent understanding to react with confidence rather than stand scratching our heads while we try to figure out exactly what we are seeing.

That is a very effective illusion.

It illustrates the effects of perspective and how we judge distance (depth perception).

In this illusion, there are two different depth cues working against each other.

Usually, on seeing three identical vans we would assume that they are all the same size (in reality) and so we use the visual size of the vans in the picture to perceive their real distance away from us. The picture is flat, so our brains construct an 3-D perception of the scene in our imagination.

However, in this picture, the perspective of the background (the road, the avenue of trees, etc.) is very strong and so we judge distance based on the perspective present in the background. The third van consequently appears about twice as far away as the first simply because it appears to be twice as far down the road (using the width of the road in the image to judge how far away it is).

The only way to reconcile this fact with the size of the vans in the image being the same is to assume that the third van is, in reality, about twice as big as the first, so that is what our brains do.

Our depth perception is remarkably sophisticated, although most people are not consciously aware of how it works.

Ha ha! Well done.

Beauty is in the eye of the beholder, as the saying goes... but our brains can easily be fooled.

Tom Axford said:

That is a very effective illusion.

It illustrates the effects of perspective and how we judge distance (depth perception).

In this illusion, there are two different depth cues working against each other.

Usually, on seeing three identical vans we would assume that they are all the same size (in reality) and so we use the visual size of the vans in the picture to perceive their real distance away from us. The picture is flat, so our brains construct an 3-D perception of the scene in our imagination.

However, in this picture, the perspective of the background (the road, the avenue of trees, etc.) is very strong and so we judge distance based on the perspective present in the background. The third van consequently appears about twice as far away as the first simply because it appears to be twice as far down the road (using the width of the road in the image to judge how far away it is).

The only way to reconcile this fact with the size of the vans in the image being the same is to assume that the third van is, in reality, about twice as big as the first, so that is what our brains do.

Our depth perception is remarkably sophisticated, although most people are not consciously aware of how it works.

Click to expand...

I think you also miss an important point here.

We do not see the vans as being the same size and assume that they get bigger with distance, our understanding that the last van in line is further away and therefore bigger even though it appears the same size... This would be the more absolute explanation consistent with perspective and geometry.

We actually see the further away van as being considerably bigger than the nearest and the only way that can happen is if the brain modifies the information it receives.

Optical illusions are not about how we interpret perspective but are a window to how the brain deals with the conflicts and information that run counter to our understanding of perspective. They are generally contrived (as in not something you see every day... ) and demonstrably false as in you can readily prove what you see is false.

And fact still remains that what you see is demonstrably false and not consistent with the information or perspective presented in the image.

Andrew564 said:

Optical illusions are not about how we interpret perspective but are a window to how the brain deals with the conflicts and information that run counter to our understanding of perspective. They are generally contrived (as in not something you see every day... ) and demonstrably false as in you can readily prove what you see is false.

Click to expand...

How do you prove that the picture does not show three vans of different sizes but otherwise identical?

FrancoD said:

Sometime I wonder about the difference between what I think we see and what we do see.

I know that these three vans are of exactly the same size (the one at the front and the one at the back are a copy and paste of the one in the middle) but I can't see it :



what do you see ?

(not my illusion).

Click to expand...

I see three vans of very different size, and only when I measure their size does my brain concede it's beeing fooled.

Thank you for sharing.

Of course it's an optical illusion. It goes to show that much of what we think we see is not what's there but what our brain thinks is there. Our brains are easily fooled.

Tom Axford said:

Andrew564 said:

Optical illusions are not about how we interpret perspective but are a window to how the brain deals with the conflicts and information that run counter to our understanding of perspective. They are generally contrived (as in not something you see every day... ) and demonstrably false as in you can readily prove what you see is false.

Click to expand...

How do you prove that the picture does not show three vans of different sizes but otherwise identical?

Click to expand...

The question you ask is convoluted and misdirects. On an image that has three vans that have the same absolute measurement you ask how do I prove that the image doesn't show three vans of the same absolute measurement? ( your bold... )

You should be asking how you prove that absolute truth of the image is different to what you perceive it to be.

And the obvious answer is:

You measure them with a ruler.

But unless you have someone telling you that they are the same relative size your automatic assumption is that if you put a ruler on the page and the first van is 6mm high then you would expect the last one to be 9mm (for example).

And the other obvious question is: "If I took this image in isolation, and only this image, what could I learn about how we see perspective?"

And the only answer you can extrapolate would be that we don't see perspective correctly.

But we both know that is not the case so I would say that we can't really use this image to show how we interpret perspective but must look again and ask what it actually does show us.

I didn't even think to do a cut/paste because I just assumed they had been resized.

My bad!

I was certainly fooled.

Possibly one of the best optical illusions that I've ever seen.

When the moon is low in the sky, near the horizon, it looks bigger. Much the same illusion.

So, at what point does the front vehicle disappear?

grsnovi said:

So, at what point does the front vehicle disappear?

Click to expand...

It will get to a minimum perceptual size, but not disappear. That will occur when the road is right alongside the camera position. At that point it stops getting closer to the camera, so the van will stop appearing to get smaller.