Mary and the black & white room

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Re: Mary and the black & white room

#61  Postby DavidMcC » Sep 06, 2012 7:03 am

Also, ramseyoptom, I do not challenge the visual acuity research, but that is not the issue. Colour perception is the issue.

EDIT: Maybe we've had 50 years of "infancy" on that, because we can't interview a baby, or get it to be interested in exactly what we want it to be.
Last edited by DavidMcC on Sep 06, 2012 7:10 am, edited 1 time in total.
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Re: Mary and the black & white room

#62  Postby DavidMcC » Sep 06, 2012 7:08 am

SOS, on the issue of consciousness, it is you that has a problem (still, it seems) with that, not I. We discussed this in detail, months ago (the role of the TC loops).
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Re: Mary and the black & white room

#63  Postby DavidMcC » Sep 06, 2012 7:27 am

SOS, concerning the Himba's perception of subtle hues of green, I would like confirmation that the experiment takes into account the known genetic variants of the MW (and even LW) opsin genes. If the Himba happen to have a different allele than the control group, then this might have more impact than cultural differences, and should certainly be taken into account.
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Re: Mary and the black & white room

#64  Postby ughaibu » Sep 06, 2012 7:34 am

DavidMcC wrote:SOS, concerning the Himba's perception of subtle hues of green, I would like confirmation that the experiment takes into account the known genetic variants of the MW (and even LW) opsin genes. If the Himba happen to have a different allele than the control group, then this might have more impact than cultural differences, and should certainly be taken into account.
Quite. The possibility that their language reflects what they see, rather than what they see reflecting their language, seems to have been neglected.
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Re: Mary and the black & white room

#65  Postby DavidMcC » Sep 06, 2012 7:35 am

ramseyoptom wrote:They work by employing the observation that a infant would rather look at a pattern than a blank stimulus ( Fantz RL, Ordy JM and Udelf MS (1962) Maturation of pattern vision in infants during the first six months Child Dev 46 3-18)

But can they distinguish between not perceiving colour and not being interested in it (relative to shade contrast)?
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Re: Mary and the black & white room

#66  Postby DavidMcC » Sep 06, 2012 7:40 am

ughaibu wrote:
DavidMcC wrote:SOS, concerning the Himba's perception of subtle hues of green, I would like confirmation that the experiment takes into account the known genetic variants of the MW (and even LW) opsin genes. If the Himba happen to have a different allele than the control group, then this might have more impact than cultural differences, and should certainly be taken into account.
Quite. The possibility that their language reflects what they see, rather than what they see reflecting their language, seems to have been neglected.


Yes, and probably what they see is more dependent on their opsin genes than on their language/culture, even though their attention to specific details in what they see may be strongly influenced by culture.
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Re: Mary and the black & white room

#67  Postby DavidMcC » Sep 06, 2012 7:52 am

One more shot at getting through to SOS about time to develop colour perception. I never said this is only a matter of retinal development. Of course it also requires VC development, which can only start after the retina starts sending signals to the brain. I am not making any particular claim about how long that takes, except that it is not years, and that babies' gaze experiments can give an exaggerated idea of that time, by playing down the role of preference of shade contrast.
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Re: Mary and the black & white room

#68  Postby DavidMcC » Sep 06, 2012 8:11 am

Another point w/r to the Himba "green hues" experiment is that it should be extended to other colour regions for a better understanding of the origin of any detected differences. Then the results can be correlated with differences in the opsin variants' peak response wavelengths, if such variants are found in the subject groups.
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Re: Mary and the black & white room

#69  Postby SpeedOfSound » Sep 06, 2012 12:37 pm

DavidMcC wrote:
ramseyoptom wrote:Preferential Looking Techniques (aka baby's gaze) have been shown to be robust and repeatable, even though they are dependent on the examiner's ability and the child's attention.

Repeatable, sure, but that only means that the possible misinterpretation is repeating.

SpeedOfSound wrote:So you think you are in a position to peer review and reject all of the cognitive studies on infants based on your thinking that baby-gaze is unreliable. Huh. As a a photobiology kind of guy you believe that it all ends after the retina develops. Where is that? 1 month? 3?

Gross misunderstanding. I am claiming that there has not been adequate peer review of those studies, except by non-skeptics of the method and assumptions of the baby's gaze method. Basically, that is becasuse there are no alternatives avaliable.
Correct me if I am wrong. You are saying that you know better than the researchers in the field of child development and the peer review process because you are a skeptic. What are your credentials here? I don't mean degrees, I mean knowledge.


The exact period of time is beside the point, except that it is not years. Any VC changes over such a period are surely about visual memory formation, not the details of perception.

I am having a lot of trouble understanding you so forgive me. I have to ask you some questions. It seems clear to me that you are saying that the only changes to the VC are memories of visual images being recorded? During the early postnatal and on up? No changes in how they perceive?


You are also continuing to make the gross error of assuming that I claim no development after the retina has formed. I never said such nonsense. What does occur is that the the thing to which the VC adapts is determined wthin a few weeks of birth.

Okay. So this says somewhat the opposite but you believe visual perception of say the color blue is fully developed after two weeks and unchanging after that?


Also, regarding the video, I think there was a misunderstanding between us over the issue of whether we were talking about major or minor differences in colour perception. I was talking about the subtle differences between different groups of adults, but you were obviously talking about the major changes that occur in a baby's visual system after birth.


Slight correction. I am talking about the major changes that occur in a baby's visual perception after birth.
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Re: Mary and the black & white room

#70  Postby DavidMcC » Sep 06, 2012 2:17 pm

SpeedOfSound wrote:
DavidMcC wrote:
ramseyoptom wrote:Preferential Looking Techniques (aka baby's gaze) have been shown to be robust and repeatable, even though they are dependent on the examiner's ability and the child's attention.

Repeatable, sure, but that only means that the possible misinterpretation is repeating.

SpeedOfSound wrote:So you think you are in a position to peer review and reject all of the cognitive studies on infants based on your thinking that baby-gaze is unreliable. Huh. As a a photobiology kind of guy you believe that it all ends after the retina develops. Where is that? 1 month? 3?

Gross misunderstanding. I am claiming that there has not been adequate peer review of those studies, except by non-skeptics of the method and assumptions of the baby's gaze method. Basically, that is becasuse there are no alternatives avaliable.
Correct me if I am wrong. You are saying that you know better than the researchers in the field of child development and the peer review process because you are a skeptic.

No, I am saying that I am skeptical of the soundness of the conclusions. I argue only that they may be making logical errors, due to filling in the gap of baby data with (albeit widely accepted) assumptions about the meaning of a baby's gaze.
The exact period of time is beside the point, except that it is not years. Any VC changes over such a period are surely about visual memory formation, not the details of perception.

I am having a lot of trouble understanding you so forgive me. I have to ask you some questions. It seems clear to me that you are saying that the only changes to the VC are memories of visual images being recorded? During the early postnatal and on up? No changes in how they perceive?


You are also continuing to make the gross error of assuming that I claim no development after the retina has formed. I never said such nonsense. What does occur is that the the thing to which the VC adapts is determined wthin a few weeks of birth.

Okay. So this says somewhat the opposite but you believe visual perception of say the color blue is fully developed after two weeks and unchanging after that?


Also, regarding the video, I think there was a misunderstanding between us over the issue of whether we were talking about major or minor differences in colour perception. I was talking about the subtle differences between different groups of adults, but you were obviously talking about the major changes that occur in a baby's visual system after birth.


Slight correction. I am talking about the major changes that occur in a baby's visual perception after birth.


Exactly. I wouldn't think of denying that the VC changes dramatically soon afer birth, only that it continues to do so for many months.
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Re: Mary and the black & white room

#71  Postby DavidMcC » Sep 06, 2012 2:21 pm

Technical aside: It is technically difficult to give a detailed response to a multi-section post, so I recommend splitting long posts into separate, single-issue ones, as I often do.
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Re: Mary and the black & white room

#72  Postby DavidMcC » Sep 06, 2012 2:28 pm

SpeedOfSound wrote:Okay. So this says somewhat the opposite but you believe visual perception of say the color blue is fully developed after two weeks and unchanging after that?

No, not at all. I said the retina to which the VC adapts is more or less complete after a couple of weeks. Of course it takes much longer (don't know how long) for the VC to adapt to the retina. However, the end-point of that process is largely determined by the details of the retina. In other words, those who only have two different cone types after a couple of weeks will probably end up with a VC suitable for those two, not three, for example.
EDIT: Also, the overall spectrum of light falling on the retina has to remain as broad as in the first couple of weeks, so that the VC is adapting to the same environment as the retina did.
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Re: Mary and the black & white room

#73  Postby DavidMcC » Sep 06, 2012 2:49 pm

My knowledge of brain development comes from papers and articles on the adaptation of the VC to the retina. Unfortunately, a key paper is lost to me, as I have said a couple of times before, to GrahamH, about the nature of the output of cone cells. The model I think makes most sense requires that different cone cell types differ by more than just the actual opsin type.
Rodents have two opsins in each of their cone cells, and are therfore considered to be monochromats with a broad wavelength sensitivity, rather than dichromats with the same overall bandwidth. If our opsins were split between identical cone cells, that would be similar to rodents, except with three opsins. In fact, the SW cones (blue) are distinct from the MW and LW cones, with even the opsin being coded for on a different chromosome from the other two - the SW cones must have evolved much earlier, in deep water, where any light is strongly biassed to the blue.
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Re: Mary and the black & white room

#74  Postby SpeedOfSound » Sep 06, 2012 3:05 pm

DavidMcC wrote:Technical aside: It is technically difficult to give a detailed response to a multi-section post, so I recommend splitting long posts into separate, single-issue ones, as I often do.


good. I like that too. A lot of people hate that so occasionally I will comply.

answer this:
... I just saw your post.
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Re: Mary and the black & white room

#75  Postby SpeedOfSound » Sep 06, 2012 3:08 pm

DavidMcC wrote:
SpeedOfSound wrote:Okay. So this says somewhat the opposite but you believe visual perception of say the color blue is fully developed after two weeks and unchanging after that?

No, not at all. I said the retina to which the VC adapts is more or less complete after a couple of weeks. Of course it takes much longer (don't know how long) for the VC to adapt to the retina. However, the end-point of that process is largely determined by the details of the retina. In other words, those who only have two different cone types after a couple of weeks will probably end up with a VC suitable for those two, not three, for example.
EDIT: Also, the overall spectrum of light falling on the retina has to remain as broad as in the first couple of weeks, so that the VC is adapting to the same environment as the retina did.


So you are saying that the perception is fully formed in V1 and there is no downstream changes affecting perception after that? It's all the retina and the landing in V1? You do allow for signal being causal in this V1 formation though?
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Re: Mary and the black & white room

#76  Postby SpeedOfSound » Sep 06, 2012 3:09 pm

You didn't answer this one.

I am having a lot of trouble understanding you so forgive me. I have to ask you some questions. It seems clear to me that you are saying that the only changes to the VC are memories of visual images being recorded? During the early postnatal and on up? No changes in how they perceive?

You are saying images are stored in the VC?
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Re: Mary and the black & white room

#77  Postby SpeedOfSound » Sep 06, 2012 3:10 pm

DavidMcC wrote:My knowledge of brain development comes from papers and articles on the adaptation of the VC to the retina. Unfortunately, a key paper is lost to me, as I have said a couple of times before, to GrahamH, about the nature of the output of cone cells. The model I think makes most sense requires that different cone cell types differ by more than just the actual opsin type.
Rodents have two opsins in each of their cone cells, and are therfore considered to be monochromats with a broad wavelength sensitivity, rather than dichromats with the same overall bandwidth. If our opsins were split between identical cone cells, that would be similar to rodents, except with three opsins. In fact, the SW cones (blue) are distinct from the MW and LW cones, with even the opsin being coded for on a different chromosome from the other two - the SW cones must have evolved much earlier, in deep water, where any light is strongly biassed to the blue.


So you admit to no knowledge about what happens after the LGN? Or V1?
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Re: Mary and the black & white room

#78  Postby DavidMcC » Sep 07, 2012 1:32 pm

SpeedOfSound wrote:
DavidMcC wrote:My knowledge of brain development comes from papers and articles on the adaptation of the VC to the retina. Unfortunately, a key paper is lost to me, as I have said a couple of times before, to GrahamH, about the nature of the output of cone cells. The model I think makes most sense requires that different cone cell types differ by more than just the actual opsin type.
Rodents have two opsins in each of their cone cells, and are therfore considered to be monochromats with a broad wavelength sensitivity, rather than dichromats with the same overall bandwidth. If our opsins were split between identical cone cells, that would be similar to rodents, except with three opsins. In fact, the SW cones (blue) are distinct from the MW and LW cones, with even the opsin being coded for on a different chromosome from the other two - the SW cones must have evolved much earlier, in deep water, where any light is strongly biassed to the blue.


So you admit to no knowledge about what happens after the LGN? Or V1?


I would say no detailed knowledge, but I can make reasonable inferences from what I do know, including that the basis of human vision is evolutionarily much older than humans, conscious thought or culture. VCs were adapting to retinae long before us.
Having said that, I am not arguing that there has been no evolution of VC development (because it clearly slowed down in mammals relative to reptiles, due to parental care), only that it should not be assumed to be profoundly affected by such add-ons as culture.
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Re: Mary and the black & white room

#79  Postby DavidMcC » Sep 08, 2012 10:13 am

More on the Himba:
http://www.bbc.co.uk/blogs/tv/2011/08/horizon.shtml
The Himba of northern Namibia ... call the sky black and water white, and for them, blue and green share the same word.

I almost wonder whether this means that they either have even fewer SW (blue) cones cells than we do (and we have far fewer SW than MW or LW cones, ourselves), or the compensatory amplification of the SW output is reduced relative to us. Either way, they would be relatively colour blind to blue. This might leave more "room" for good colour discrimination in the green, especially if the shorter wavelength MW cone opsin has been selected for in them.
This is speculative, but, as Africans generally are more genetically diverse than alll the non-Africans put together, it may even be that they have their own version of the MW opsin, with an even shorter wavelength peak, as a knock-on effect of having no SW cones. Unless someone has studied in detail the Himba X chromosome (where the MW opsin gene lies), we do not know for sure.
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Re: Mary and the black & white room

#80  Postby DavidMcC » Sep 08, 2012 12:22 pm

It has just occurred to me that a simple question to a Himba about how he/she sees a rainbow would be useful to help us understand colour perception in the rest of us. That question is: "When you see a rainbow, do you see a second, dim red band on the inside of the curve?" If they do see that (where we see violet), it would show that the LW opsin does, indeed have a second, weak peak at the short wavelength end of the spectrum. If they do not see it, then that is not the explanation of violet. There are, of course, three possible answers to the more general question of what they see where we would see violet - nothing at all, dim red, or a different colour altogether. The third option seems unlikely, given the small number of words they have for colours.
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