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Optical illusions creating color

Before colour TV I remember seeing a B&W image on Tomorrow's World, IIRC, that produced a colour effect. It was a sort of reddish brown, but quite noticeable. I think it was Benham's disk.

Another interesting illusion I saw on TV a few years ago was 3D. I can't remember how they did that either (something to do with camera movement?) but it worked very well. It was the last few minutes of an Eastenders episode.

Leon
 
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Olowkow said:
Actually, the original spinning stuff does not work for me at all. I tried it several times, and I just can't see the colors.
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I think I can see yellow.

The reason I'm interested in this is because of the Knowledge Argument.

~~ Paul
 
Paul C. Anagnostopoulos said:
I think I can see yellow.

The reason I'm interested in this is because of the Knowledge Argument.

~~ Paul
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As in:
http://plato.stanford.edu/entries/qualia-knowledge/
I take it. I started reading and my eyes glazed over. I'll leave this one to the smart guys. Just curious though how it relates to the illusion.

The knowledge argument aims to establish that conscious experience involves non-physical properties. It rests on the idea that someone who has complete physical knowledge about another conscious being might yet lack knowledge about how it feels to have the experiences of that being. It is one of the most discussed arguments against physicalism. [sic]
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For a fun book covering these topics amongst others, read "Mind Hacks": http://safari.oreilly.com/0596007795

I remember a discussion I had with a friend a late night after way too much head-to-head Tetris: Is our perception of colors alike. Would I, if I could somehow borrow his vision, perceive "red" as "red" or would his "red" be my "blue" (or some other color)?

If I remember, we discussed this for a good while before our heads started to hurt too much.. :blush:
 
In Australia, well before colour TV, one of the petrol companies ran this commercial, by flickering various parts of the image at different rates that managed to fool the eye it was seeing colour

Was always impressed by that lol
 
erlando said:
For a fun book covering these topics amongst others, read "Mind Hacks": http://safari.oreilly.com/0596007795

I remember a discussion I had with a friend a late night after way too much head-to-head Tetris: Is our perception of colors alike. Would I, if I could somehow borrow his vision, perceive "red" as "red" or would his "red" be my "blue" (or some other color)?

If I remember, we discussed this for a good while before our heads started to hurt too much.. :blush:
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I've smoked way too much head-to-head Tetris on occasion myself. The end result is that it does not matter, or three is a shift. An EM shift could be easily detected. Otherwise, it is a matter of description. They could be different but describe the same by some miracle of chance. But it is more likely they are the same because they use the same functions for interpretation. In the unlikely event they do not, there would be no noticeable difference. So who, other than philosophers, would care?
 
I don't think Benham's disk has anything to do with the Knowledge Argument. In the Knowledge Argument, the question is asked if it is possible to explain the sensation of seeing a certain colour to somebody who has never seen colours. The phenomenon of Benham's disk is that somebody with normal colour vision will see colours produced from the movement of a black and white pattern.

The Benham's disk effect is a special case of the Fechner colour effect. I don't know what the explanation for this effect is - I don't think there is a generally accepted explanation, just a few conjectures. I looked at the page you linked to and was surprised to be able to see the effect on a computer screen. I think it's stronger with a real top.
 
Michael C said:
I don't think Benham's disk has anything to do with the Knowledge Argument. In the Knowledge Argument, the question is asked if it is possible to explain the sensation of seeing a certain colour to somebody who has never seen colours. The phenomenon of Benham's disk is that somebody with normal colour vision will see colours produced from the movement of a black and white pattern.
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Ah, but doesn't this open up the possibility that with her complete knowledge of physics, Mary could create black-and-white optical devices that would enable her to learn to see color?

The operative phrase is "complete knowledge of physics." That's a helluva lot of information.

~~ Paul
 
Paul C. Anagnostopoulos said:
Ah, but doesn't this open up the possibility that with her complete knowledge of physics, Mary could create black-and-white optical devices that would enable her to learn to see color?
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The essential point of the Knowledge Argument thought experiment is not that Mary only has black and white things at her disposal. The point is that all her life, she has been prevented from seeing any colours.

She has the knowledge, for instance, that colours can be made by passing white light through a prism. Therefore she would not have access to prisms, or any other devices with which she could refract light. Since she also has the knowledge that Benham's top produces sensations of seeing colours, she would be prevented from making such a top.

She'd also need to be prevented from seeing her own body. In fact the best method for the evil experimenters would be to find a way to induce total monochromatic colour-blindness in the brain. But there's no point in going on into more details: this is a thought experiment where the only important point is that Mary has never seen a colour.
 
Michael said:
The essential point of the Knowledge Argument thought experiment is not that Mary only has black and white things at her disposal. The point is that all her life, she has been prevented from seeing any colours.
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Fair enough, but then if the argument refutes anything, it refutes some sort of physicalism-prime, not the physicalism that describes our world, nor any sort of generic physicalism. In particular, what if it is possible for Mary to know what it's like to see color once she learns everything about the physical world, but only if her brain is intact?

It doesn't matter all that much, since physicalism doesn't require that I be able to establish arbitrary brain state by reading books. But it's still a great source of discussion.

From http://plato.stanford.edu/entries/qualia-knowledge/:

Some authors have raised doubts about the thought experiment itself. It is sometimes pointed out, for example, that merely confining Mary to a monochromatic environment would not prevent her from having color experiences (see Thompson (1995), p. 264) or that, after release, she would not be able to see colors. But the example can be refined to meet these objections. Mary might be monochromatic from birth and changed into a normal perceiver by some medical procedure. It is sometimes objected that already accepted or future results of visual science are or might be incompatible with the existence of a Mary-case (a person with monochromatic experience who becomes a normal color perceiver later) or that such results might require (to preserve consistence with visual science) the introduction of so many additional assumptions that the conceivability of the example becomes doubtful. To this one might reply that the thought experiment need not be compatible with visual science. If the case of a person with monochromatic vision who turns into a normal perceiver really does involve serious difficulties for materialism, then the mere fact (if it were one) that our visual apparatus excludes the actual existence of such a case does not seem to provide a convincing reply for the materialist. But this point (the relevance or irrelevance of visual science in this context) has not received much discussion in the literature. It has, however, been pointed out (see Graham and Horgan, 2000, footnote 4 with its reference to Shepard (1993)) that at least presently available results of color vision science do not exclude a Mary-case. (The psychologist Knut Nordby is a real life case of a color vision specialist who is also a complete achromat. See his paper ‘Vision in a Complete Achromat: A Personal Account’, linked into in the Other Internet Resources section.)
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Emphasis mine.

~~ Paul
 
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