Neat optical illusion

[Paul C. Anagnostopoulos]

In both cases (receptive fields and trichromatic theory), the sensory apparatus mechanisms are part of the illusion (indeed, it would not happen without it); both are part of what Ian's ideal observer must experience. Both, to Ian, are part of the outside-of-observer, seemingly physical (although I think Ian would perhaps argue that we cannot assume they are physical, since the only evidence we have for them is experiential) world. Ian's observer is not dependent on such things, but on the experience itself.

But then why does Ian insist that color is in the sensory apparatus rather than in the image? If both the sensory apparatus and the image are outside-of-observer, why argue so strongly for color being in one as opposed to the other? Neither are in the privileged position of observer, which I believe is where Ian wants color to lie.

Ian has said that the Metamind plays the external world on the senses of the observer. This makes it sound as if the senses are not part of the external world, are not outside-of-observer.

I remain confused.

~~ Paul

 

[Raphael]

Lots of fun- thanks 42

Adelson’s illusion- This really makes you think about how we interpret the outside world based on previous experience. I ended up making a template with the two squares cut out, and moving it about on my monitor trying to find positions where the shades matched and changed.

 

[tsg]

Lots of fun- thanks 42

Adelson’s illusion- This really makes you think about how we interpret the outside world based on previous experience. I ended up making a template with the two squares cut out, and moving it about on my monitor trying to find positions where the shades matched and changed.

This is what convinced me:

The wierd thing is that when you use the color grabber on the B square, it still looks much darker.

 

[CFLarsen]

Did he deny it even after being shown the truth?

Ayup.

Did he try chopping out a bit of square A in a graphics program and dragging it over B? :-D

Nope.

I find the people who most vehemently defend indefensible positions are usually those least willing to try simple experiments for themselves -- experiments that would quickly demonstrate what's going on.

Ayup.

We should cherish Ian.

 

[CFLarsen]

But then why does Ian insist that color is in the sensory apparatus rather than in the image? If both the sensory apparatus and the image are outside-of-observer, why argue so strongly for color being in one as opposed to the other? Neither are in the privileged position of observer, which I believe is where Ian wants color to lie.

Why? Because Ian believes that he creates the world in his mind. We are all figments of his imagination.

Ian has said that the Metamind plays the external world on the senses of the observer. This makes it sound as if the senses are not part of the external world, are not outside-of-observer.

I remain confused.

~~ Paul

That's natural, when you are dealing with Ian.....

 

[Dog Boots]

This is what convinced me:
[qimg]http://www.internationalskeptics.com/forums/imagehost/59414490fc75975c9.jpg[/qimg]

The wierd thing is that when you use the color grabber on the B square, it still looks much darker.

My living room walls are blue, sort of like the forum buttons blue. When I got my video projector, I installed it on a shelf on the wall, projecting on to the opposite wall. I then proceeded to paint the exact area of the projected image white, to function as a screen, but before I did that, I had no trouble convincing my brain, that the white parts of an image were really, completely white - even though they were really baby blue.

It's also amazing to watch something on there when the room is not darkened, and look how black the black parts of the image looks, but when you look at another part of the wall, which is white just like the screen - it looks white - not black.

Btw. that dragon is just creepy! I also made one myself (at 3:30AM over here) when I discovered it - and it's addictive! Highly recommended!

 

[El Greco]

An amazing such illusion appears in a BBC documentary about the brain. It's two girls in the same room, but one appears to be twice as big as the other. When they move next to each other you realize they are of the same height. The furniture and the walls in the room have been scaled so as to create that illusion.

 

[Paul C. Anagnostopoulos]

Why? Because Ian believes that he creates the world in his mind. We are all figments of his imagination.

No, I believe he thinks that the Metamind plays the external world on our senses (or something), so that the external world is a construct of the Metamind.

~~ Paul

 

[I less than three logic]

Did he deny it even after being shown the truth? Did he try chopping out a bit of square A in a graphics program and dragging it over B? :-D

No, no, no. That’s Cheating.

http://www.internationalskeptics.com/forums/showthread.php?postid=1506305#post1506305

 

[ceptimus]

It comes down to whether you think the word 'color' refers to an intrinsic property of an object, or what is perceived by the mind. Ian uses the latter meaning, and his position seems logically consistent to me.

What color is a piece of white paper when there is no light? Ian would say (I think) that it's black - so paper stored in a lightproof box is black, and it only becomes white when you take it out into the daylight. It may seem like a strange way of considering things to most people, but I don't think that makes it wrong necessarily.

Another thing. In the case of the Adelson image, if you say that the image is a representation of a 3D scene, then the original 3D squares are indeed different colors - it is only on the 2D representation that they're the same - as one happens to be in shadow.

In the 2D representation, the 'squares' aren't actually square - so the fact that people refer to them as 'squares' should mean that they are referring to the 3D object represented. If you accept this, then Ian is right.

 

[Mercutio]

An amazing such illusion appears in a BBC documentary about the brain. It's two girls in the same room, but one appears to be twice as big as the other. When they move next to each other you realize they are of the same height. The furniture and the walls in the room have been scaled so as to create that illusion.

That is the classic Ames room.

 

[Tirdun]

It comes down to whether you think the word 'color' refers to an intrinsic property of an object, or what is perceived by the mind. Ian uses the latter meaning, and his position seems logically consistent to me.

The interpretation of color is not the same as the inherent color of an item. A white piece of paper in no light is still white, it is never "black". If I put it under red lights it appears red, but it is still a white piece of paper because it reflects all available visible light in a diffuse pattern equally, which is the definition of white. Color is based on the physics of light, interpretation is based on how our brain works.

In the case of the Adelson image, if you say that the image is a representation of a 3D scene, then the original 3D squares are indeed different colors - it is only on the 2D representation that they're the same - as one happens to be in shadow.

It is a 2D image that we interpret as if it were a 3D scene. The interpretation changes the color in our mind, but nothing changes the fact that the two squares share the same color wavelength. Because it appears to be a 3D scene, our brain makes certain adjustments for the depth of the scene and apparent effect of the cylinder's (or what we perceive to be a cylinder) shadow.

if [...] Ian is right.

I disagree. If you change the visual input, the color interpretation will change, such as by blocking elements of the picture or overlaying a common color. I had to print the picture out to prove it to someone, using a fold. They were mostly convinced, but used the soft copy to check the actual color values in an editing program. Sometimes knowing an illusion is present will ruin the effect, but the cubes are so pervasive that we continue to believe, even if we know otherwise.

Regardless, our interpretation of what color the blocks are doesn't change the fact that they are, by definition, the same color.

 

[Mercutio]

Regardless, our interpretation of what color the blocks are doesn't change the fact that they are, by definition, the same color.

But that is precisely the point. Your (and most others) define "the same color" by reference to the physical properties. Yet one cannot deny that two different "surrounds" can make the same physically defined color appear to be two quite different colors. If our definition has as its bedrock the appearance of the color, then they are, by definition, not the same color, despite having the same physical properties.

The job of perceptual science (explaining the relationship of external stimulus to internal perception) remains the same; we are simply solving for a different variable. Metaphorically, instead of regressing perception onto stimulus, we are regressing stimulus onto perception. What Ian is doing here solves the same problem Fechner did over a century ago when he invented psychophysics.

Indeed, in some visual perception experiments, the task of the subject is to perform "color matching", in which two different mixes of wavelengths are manipulated until they appear to be the same color. This is perfectly good science, it gives us good data on the relative spectral sensitivities of the cone cells, and it does so by treating the perceived color as the standard.

I am not saying Ian's way is superior, merely that it is logically coherent and useful.

 

[tkingdoll]

But that is precisely the point. Your (and most others) define "the same color" by reference to the physical properties. Yet one cannot deny that two different "surrounds" can make the same physically defined color appear to be two quite different colors. If our definition has as its bedrock the appearance of the color, then they are, by definition, not the same color, despite having the same physical properties.

The job of perceptual science (explaining the relationship of external stimulus to internal perception) remains the same; we are simply solving for a different variable. Metaphorically, instead of regressing perception onto stimulus, we are regressing stimulus onto perception. What Ian is doing here solves the same problem Fechner did over a century ago when he invented psychophysics.

Indeed, in some visual perception experiments, the task of the subject is to perform "color matching", in which two different mixes of wavelengths are manipulated until they appear to be the same color. This is perfectly good science, it gives us good data on the relative spectral sensitivities of the cone cells, and it does so by treating the perceived color as the standard.

I am not saying Ian's way is superior, merely that it is logically coherent and useful.

My husband had an interesting response to the checkerboard illusion. I showed it to him, and the question underneath says "Are squares A and B the same shade of grey? "

His answer was no. I laughed, thinking he'd fallen for the obvious, and said "actually, they are the same", and showed him in Photoshop.

He replied "that's not what I meant. The question was are the squares the same shade of grey. They are not. In the checkerboard pattern, one is a light square and the other is a dark square. They have the appearance of being the same shade when you put them together because the B square has a shadow cast over it from the green cylinder. It's artificially the same colour as A but in the reality of the board, it is not".

 

[I less than three logic]

My husband had an interesting response to the checkerboard illusion. I showed it to him, and the question underneath says "Are squares A and B the same shade of grey? "

His answer was no. I laughed, thinking he'd fallen for the obvious, and said "actually, they are the same", and showed him in Photoshop.

He replied "that's not what I meant. The question was are the squares the same shade of grey. They are not. In the checkerboard pattern, one is a light square and the other is a dark square. They have the appearance of being the same shade when you put them together because the B square has a shadow cast over it from the green cylinder. It's artificially the same colour as A but in the reality of the board, it is not".

Yes, but that is the illusion. There never was a real checkerboard, this is not a photograph. It was drawn with the very intention of making square A and square B the exact same shade of gray, and simultaneously fooling the brain into believe they are different colors. You do not need to move the squares to make them appear the same color, only remove the other visual cues your brain is receiving from the picture.

One of the best ways to observer this is to print the picture, then with a separate piece of paper cut out two squares that will allow you to see only square A and B. Place the paper over the picture and the two squares are the same color, remove the paper and they look different again. It is your brain creating the difference in color. The artificial color created is not “a shadow on a light square making it appear as the same color as the dark square”, the artificial color is your brain’s interpretation that “it is a light square within a shadow, and therefore must be a different color from the dark square”. That is the illusion.

 

[tkingdoll]

Yes, but that is the illusion. There never was a real checkerboard, this is not a photograph. It was drawn with the very intention of making square A and square B the exact same shade of gray, and simultaneously fooling the brain into believe they are different colors. You do not need to move the squares to make them appear the same color, only remove the other visual cues your brain is receiving from the picture.

One of the best ways to observer this is to print the picture, then with a separate piece of paper cut out two squares that will allow you to see only square A and B. Place the paper over the picture and the two squares are the same color, remove the paper and they look different again. It is your brain creating the difference in color. The artificial color created is not “a shadow on a light square making it appear as the same color as the dark square”, the artificial color is your brain’s interpretation that “it is a light square within a shadow, and therefore must be a different color from the dark square”. That is the illusion.

Well, not necessarily. As I stated, I showed him the two squares together (I used Photoshop, see my link in an earlier post), but his point was that your brain identifies them as different because of your expection of the pattern of a checkerboard, so the 'reality' of the board is relevant.

What we don't know (yet, it's pretty easy to find out) is what colour square B is without the shadow. If it's the same as the light squares surrounding square A, then his point is valid.

 

[CFLarsen]

Deleted.

 

[Meffy]

[edit] Comments struck to avoid further Ianization of thread.

 

[Upchurch]

Did he deny it even after being shown the truth? Did he try chopping out a bit of square A in a graphics program and dragging it over B? :-D

I find the people who most vehemently defend indefensible positions are usually those least willing to try simple experiments for themselves -- experiments that would quickly demonstrate what's going on.

Some history

 

[Meffy]

Thanks... *reads* *chokes* Just 52 pages? S'arright, I'll take the sampling as reprsentative and hope for the best.