sciencedaily.com — First-ever images of living human retinas have yielded a surprise about how we perceive our world. Researchers at the University of Rochester have found that the number of color-sensitive cones in the human retina differs dramatically among people?by up to 40 times?yet people appear to perceive colors the same way.
Oct 26, 2005 View in Crawl 4
nickelsaxOct 27, 2005
krapsystem,Maybe to explain the point alecks was making in a way you may understand better. As Humans we learn to call the colour we see when we see electro-magnetic radiation with a wave length of 700nm as red, and if it has a wave length of 470 as blue (or the equivielt words in one of the many other languages we speak) But how do you know that what I "see" when I look at a wave length of 700nm, is not what you "see" when you look at a wavelength of 470nm? To both of uss 700 is red and 470 is blue, as that is the word we have always associated with what we see even if what we see is different.
alittlemeltyOct 27, 2005
@ MePhelpsRight on, man. That's exactly what I'm thinking. Thanks for putting it into much better words that I could have.
ottoOct 27, 2005
"Think about this. Every tried on someone else's glasses? Everything looks weird, out of focus, or out of perspective... I always wondered if that's how the other person sees (but in opposite of the glasses, since the glasses neutralize the effect...)"Ever gotten an eye exam? They put these drops in your eyes to dialate them, and everything goes all out of focus for several hours. It's rather annoying, actually. But if you try putting some glasses on, you'll find things are much improved (depending on the prescription of the glasses of course)."They did a test once, where they made these gogles that someone wore, but they showed everything upside down. Eventually the person adaps to the upside down vision and performs normally. Now if you ask this person which way is up, they'll point in the same direction as you, but they see everything upside down."You didn't mention the most interesting part of that experiment. While they needed people to lead them around for a few weeks, after that, the subjects reported that everything flipped, that they no longer saw everything upside down, after a few weeks. Literally, their brain "rewired" itself to flip the image back to the way it was supposed to be.Then, after removing the glasses, they saw everything as upside down again and had to be led around until their brain "rewired" once more.
noamsmlOct 27, 2005
First of all, I do think it's possible that we experience colors, reality etc in slightly different ways, but that since we always experience the RELATIONS the same way, it doesn't matter. My yellow may not be your yellow, but my red and my yellow relate the exact same way your red and your yellow do."Down" is also a relation. It is saying which visual direction relates to which "feelable" direction. Therefore, the subjects "knew" that the visual direction we relate with the navigational direction of "up" is now related to the navigational direction of "down". Otto: "Then, after removing the glasses, they saw everything as upside down again and had to be led around until their brain 'rewired' once more."Which leads us back to the original idea: They precieved "down" similarly to the way they did when their eyes precieved things differently, showing that the way "down" is precieved is independent of changes to the nevous system. That is what the experiment is trying to show in relation to color. A better way to do it would be to go through subjects as their age progresses, check the difference in the color cones (considering that some color cells may die as age progresses), record the colors they chose, and then show them what they chose each last time and ask them to say if it looks right.That way, it shows that the same person, with the same experience of "yellow", has or does not have the same experience when the amount of color cones changes.
Closed AccountOct 28, 2005
alecks unlike some of the other posters I know EXACTLY what you are saying and agree 100%It is a concept hard to grasp (I guess) for a lot of people.
mikellyOct 28, 2005
Otto: "In other words there's a continuous change along the color band that we both perceive."Again, I can maintain that the continuity of the color spectrum is an effect of the continuity of physical stimuli. If frequency y is between frequency x and z then we would likely agree that our experience of frequency y, as a color, is closer to frequency x's color than x's is of z's. In other words, the relation of frequencies does correlate to the relation of colors perceived but still does not determine how this color spectrum will be experienced.Otto: "The similarities in our perception shows us that we perceive color, in every measurable aspect, in the same way."Careful, you're begging the question here.Otto: "Now, certainly, you can postulate a completely different type of perception that just happens to have a one-to-one mapping with everybody else's perception on the planet... of course, you have to populate 6 billion different perceptions"Well this is tough because the mapping of physical stimuli to mental experience is a huge mystery. No one knows for certain how this mapping occurs.To push the argument forward, here is what I can't sort out. The article states that we have substantially different hardware in our eyes yet we can all pick out the purest shade of yellow. Conclusion is that our brain does some major calibrating to keep our color perception in line with everyone else's. The question I have then is how does the brain calibrate itself? It seems to me the brain must have a reference point, i.e., be told what the purest shade of white is and shift the spectrum accordingly. Then the worry of course is that the brain must 'know' what yellow is like. The colored contact lens experiment showed that over time the brain can correct an artificial offset in the color spectrum. How? It seems to me that it would only be able to do so based on previous experience. For instance, if I know that the walls in my room are 'white', then when my contact lenses are put in place and I now see the walls as yellow, I know there is a problem. (This is much like the upside down glasses experiment I think.) So my brain will do its best to make those walls white again in turn restoring all color perception to its correct state. However, without this prior experience, I do not see how the brain could know how to correct itself. In my example, my memory of white walls is my means of calibrating. What hope would someone with those lenses in place from birth have?
ottoOct 28, 2005
"Otto I think you may understand what he is saying, but your argument is faulty. Although we may be able to identify the same wavelength of light as a certain color your yellow will match my yellow, there is NO scientific way to determine what color we are actually perceiving (in our minds)."I think we have some kind of fundamental disconnect here. You can not determine what the actual perception would be if there was a "mind switch" or something equally silly like that, certainly. However, from other sorts of measurements, you *can* determine that two people's perceptions are actually identical. So while I can't tell what one person "sees" in his head, I can determine that two people "see" something extremely close to one another. Just because I can't tell what's going on in your skull precisely doesn't mean I cannot use different aspects of color and color perception to compare two people and find any differences between them."In other words, the relation of frequencies does correlate to the relation of colors perceived but still does not determine how this color spectrum will be experienced."No, but simple experiments can be devised for each of the aspects of that experience to determine that two people are experiencing the same thing. Like I said, everybody perceives a pure yellow as a brighter color than a pure blue."The question I have then is how does the brain calibrate itself? It seems to me the brain must have a reference point, i.e., be told what the purest shade of white is and shift the spectrum accordingly. Then the worry of course is that the brain must 'know' what yellow is like....It seems to me that it would only be able to do so based on previous experience."You are basically correct. Experiments with animals and color perception have shown that early development calibrates the system, because interfering with that from birth and then removing the interference results in an inability for the system to cope properly. Like if you raise a rat in a blue glass cage, then take him out, he'll never be able to see the color blue properly. That sort of thing. Google "color percception experiments" for more info on this, there's lots of interesting reading.
chosenone_Oct 28, 2005
Awesome discussion, everyone. I like the fact that Otto is being bombarded but keeps coming back :) Cheers to you, thou art a true educator. Funny thing is, right after reading the article the first thing that crossed my mind was to come here and talk about my "what if my blue is your red" idea. How surprised I was!But people, in order to evaluate the whole colour issue, we need to think about how we perceive the world. Unfortunately in our educational material we often get the notion that our eyes merely capture a flipped version of the external world, much alike to a camera.This is not true. Scientific research (if you're that skeptical I can get the names and titles :) has shown that our eyes do not operate on this level, none of our senses do. Instead, our senses are more akin to pattern recognizers and decipherers. The external world we percieve (as a collective) is constructed by our mind of the abstract mass (quantum probability) into something tangiable.Sounds abstract, I know. But read about it.My stance on the colour issue? We'll never be able to know. And brightness is independent from hues, stop it Otto! :)
noamsmlOct 28, 2005
One thing I think we can all agree on is that asking all people to point to the color "yellow" says nothing about differences in color perception, because of the fact that learned language tells us what to view as yellow regardless of weather we perceive it similarly to other people.Otto:The similarities in our perception shows us that we perceive color, in every measurable aspect, in the same way. Now, certainly, you can postulate a completely different type of perception that just happens to have a one-to-one mapping with everybody else's perception on the planet... of course, you have to populate 6 billion different perceptions... and they all have to map to each other as well... Hmm. The odds start to seem a bit longer, don't they?First of all, your argument is flawed since you are assuming that if two people do not perceive color similarly, *all* 6 billion people must be each perceiving color differently. I would not be surprised if, in the case of differences between perception of colors, it goes along in certain fractions.Secondly, you must remember that it's not about "mapping to other people's perception". There are real relations between colors, and they are inherent to their wavelength. Thus, there is no need to map to someone else's perception, just like our (sligtly different) perceptions of some occurrence don't "map" to each other.Otto:The similarities in our perception shows us that we perceive color, in every measurable aspect, in the same way. Now, certainly, you can postulate a completely different type of perception that just happens to have a one-to-one mapping with everybody else's perception on the planet... of course, you have to populate 6 billion different perceptions... and they all have to map to each other as well... Hmm. The odds start to seem a bit longer, don't they?First of all, your argument is flawed since you are assuming that if two people do not perceive color similarly, *all 6 billion people* must be each perceiving color differently. I would not be surprised if, in the case of differences between perception of colors, it goes along in certain fractions.Secondly, you must remember that it's not about "mapping to one another's perception". There are real relations between colors, and they are inherent to their wavelength. T
izzardOct 28, 2005
Great discussion. And until this point, I thought I was the only person who considered we might not all have the same experience of co lours, as Alecks first tried to point out.