The lens of our eyes projects the image to the retina at the back of our eyes upside-down, so why don’t we see everything upside-down?
By far the most common explanation is that the brain at some point turns the image back the right way up before we perceive it.
But this is a common fallacy (even amongst some of the most intelligent people) !
-for it is “unnecessary” for the brain to turn the image the other way up.
But, if that is true, what is so erroneous about the concept that it is necessary for it to be turned the right way up for us to see it the right way up?
-I am sure there are many ways of explaining this but I hope somebody a lot smarter with words than I am can explain it in such clear and simple terms that the vast majority of laypeople can understand it and without much chance of misunderstanding it.
I have, so far, failed to find a “good” way of wording the explanation for this even though I do very clearly “know” the answer to this.
Once saw a documentary on tv where volunteers had goggles on which inverted everything they saw ... took them 1-2 days to adjust. (Walking was a problem at first but finally they could ride a bike and catch a ball etc).
Interesting thing was when they took goggles off... It took the same amount of time to readjust!
Mysterious thing the brain
Originally posted by Andrew HamiltonI suppose the easiest way to explain is to separate "sensing" from "perception". The retina "senses" the inverted image coming through the lens, but the brain "perceives" the image as the end result of information processing designed to take inverted images as an input.
The lens of our eyes projects the image to the retina at the back of our eyes upside-down, so why don’t we see everything upside-down?
By far the most common explanation is that the brain at some point turns the image back the right way up before we perceive it.
But this is a common fallacy (even amongst some of the most intelligent people) !
...[text shortened]... way of wording the explanation for this even though I do very clearly “know” the answer to this.
I think it's similar to using an ATM. Some machines take your card face down, some face up, some require a swipe with the stripe on the left, some require a swipe with the stripe to the right, but the information from your card always gets read.
Here's the way I understand it..
The brain functions to take the image as it occurs on the back of the retina and determine the frame of reference. This includes things like figuring out which way is up, as well as correlating the two (slightly different) versions of what is being "seen". After some time, we take this information on how to interpret what we see for granted.
With the "upside-down-vision" goggles, we suddenly find ourselves in a place we are not accustomed to, a place where up is in the opposite direction. Our brains must therefore "unlearn" how to interpret what the eyes see in order to determine the new rules on reading the retinal maps.
This same process occurs whenever the goggles are removed after sufficient time to get used to the upside-down vision, because the frame of reference once again reverses on us.
I suspect that if you repeated the process enough times, the required time to adjust would reduce, as our minds would get used to the flip-flopping process.
Now, as for why we don't see things as "upside-down" whenever the physics of the eyes would dictate that is the way it is mapped onto the retina, I don't know.
It may be that the map is "flipped" in transit, or it may simply be that our minds "flip" it in the manner in which they translate the upside-down image to our thoughts. However the process occurs, what we see moreorless matches what is before us.
I think that Bananarama was close to giving the kind of carefully worded explanation I wanted.
I think I should ask a similar question:
Suppose a layperson stubbornly insisted and with overconfidence that the brain MUST physically flip the image the other way else we WILL all see the image upside-down;
What carefully worded argument could you give such a person that would almost guarantee that he would see error in his reasoning?
This is so far my best take on it so far:
I would explain to such a person that I think what he thinks is that, when we “see” something, there is an image in the brain that corresponds to the image on the retina (no problem there) but, and I think this is where such a persons reasoning is going wrong, that this image in the brain is there in a similar physical sense that the image on the retina in the sense that its physical orientation makes a difference!
I would then explain to him that the physical orientation makes no difference using the following Reductio ad absurdum argument:
Lets say, for the sake of argument, that the physical orientation of the image in the brain makes a difference. Now lets suppose a drunk brain surgeon opens up your skull to examine your brain, sees that nothing is wrong with it, and then clumsy puts it back into your skull upside-down and without breaking any brain or optic nerve connections (the optic nerves will have to be stretched and twisted a bit but otherwise left undamaged and fully functional and able to transmit signals through their entire length) and the retinas and your eyes both stay the same way up as before the operation.
After such an operation, would you see everything upside-down?
-if you think the answer is no, then surely you would now intuitively see that the physical orientation makes no difference.
-but if you think the answer is yes, then consider this:
every connection between any two given brain cell is exactly the same as it was before the brain was turned upside down except they are now physically upside-down but that has no effect on their behaviour and thus there cannot be any difference to the behaviour or processes in the brain and therefore there should be absolutely no difference in the perception of what is seen (including which way up it is perceived) because perception consists of certain processes in the brain and those certain processes, just like all of the processes in the brain, are unaffected by their physical orientation.
I am not sure if such a layperson would necessarily fully understand or be convinced of this explanation;
can anyone make a more convincing argument to such a layperson?
Originally posted by Andrew HamiltonMy guess is that a layperson is most likely imagining a tiny homunculus inside their head, watching a screen with the inverted image on it. Any homunculus argument is fallacious, because it begs the question of "well, what's happening inside the homunculus as it performs said task?" which leads to an infinite regress.
I think that Bananarama was close to giving the kind of carefully worded explanation I wanted.
I think I should ask a similar question:
Suppose a layperson stubbornly insisted and with overconfidence that the brain MUST physically flip the image the other way else we WILL all see the image upside-down;
What carefully worded argument could yo ...[text shortened]... convinced of this explanation;
can anyone make a more convincing argument to such a layperson?
The best way to break this belief? Show them this picture, and ask them if they really believe this is going on inside their head:
http://upload.wikimedia.org/wikipedia/commons/6/65/Cartesian_Theater.jpg
Originally posted by PBE6that stove is old school
My guess is that a layperson is most likely imagining a tiny homunculus inside their head, watching a screen with the inverted image on it. Any homunculus argument is fallacious, because it begs the question of "well, what's happening inside the homunculus as it performs said task?" which leads to an infinite regress.
The best way to break this belief? Sho ...[text shortened]... nside their head:
http://upload.wikimedia.org/wikipedia/commons/6/65/Cartesian_Theater.jpg
Originally posted by Andrew Hamiltonwhy overcomplicate something to a layperson. they are a layperson for a reason after all.....
I think that Bananarama was close to giving the kind of carefully worded explanation I wanted.
I think I should ask a similar question:
Suppose a layperson stubbornly insisted and with overconfidence that the brain MUST physically flip the image the other way else we WILL all see the image upside-down;
What carefully worded argument could yo ...[text shortened]... convinced of this explanation;
can anyone make a more convincing argument to such a layperson?
Just ask them when they touch a cold object if they think that's how the object is in reality? The object itself is NOT "cold". It is just our brain sensing a loss of heat from our body.
Originally posted by deriver69-good one:
Maybe the brain is upside down so the images are the correct way up
So maybe I should ask such a layperson:
“how do you know it is the brain that turns the image the right way up rather than it being the case that the brain is upside down so that the image doesn’t need turning the right way up?”
-although this question assumes the very same erroneous concept that I want to expose as erroneous.
Originally posted by Andrew HamiltonWhy are you going around pummeling laymen with questions, anyway?
-good one:
So maybe I should ask such a layperson:
“how do you know it is the brain that turns the image the right way up rather than it being the case that the brain is upside down so that the image doesn’t need turning the right way up?”
-although this question assumes the very same erroneous concept that I want to expose as erroneous.
Originally posted by Andrew HamiltonWhen I hear a question like this, I just avoid answering it, sit back and hear other try to explain it. I enjoy hearing people answeing these kind of questions.
The lens of our eyes projects the image to the retina at the back of our eyes upside-down, so why don’t we see everything upside-down?
By far the most common explanation is that the brain at some point turns the image back the right way up before we perceive it.
But this is a common fallacy (even amongst some of the most intelligent people) !
...[text shortened]... way of wording the explanation for this even though I do very clearly “know” the answer to this.
Because there is no answer. There is no up and down in the brain. Only in our perception of the world.
Originally posted by PalynkaWe are probably all laymen here -and I think that includes any neurologists! for I don’t see why studying neurology would necessarily make you less prone to this common misconception because, as far as I am aware, there is nothing in neuroscience that specifically says nor implies that this concept is erroneous? (please would a neurologists correct me here if I am wrong).
How many here are neurologists and how many are laymen?
Or, maybe a person that has studied the “scientific philosophy“ of the “philosophy of perception” (not sure what the proper name for this would be) is the only kind of person that isn’t the layperson here?