Philosophy Now Forum

• One of the most fascinating recent developments in neuroscience concerns the functioning of our visual system.
  
  How do we see?
  How do we know that what we have in front of us is a book, or a cat?
  It would seem natural to think that receptors detect the light that reaches the retinas of our eyes and transform it into signals that race to the interior of the brain, where groups of neurons elaborate the information in ever more complex ways, until they interpret it and identify the Objects in question.
  Neurons recognize lines that separate colors, other neurons recognize shapes drawn by these lines, others again check these shapes against data stored in our memory.
  Others still arrive at the recognition: it’s a cat.
  
  It turns out, however, that the brain does not work like this at all.
  It functions, in fact, in an opposite way.
  Many, if not most, of the signals do not travel from the eyes to the brain; * they go the other way, from the brain to the eyes.132
  
  What happens is that the brain expects to see something, on the basis of what it knows and has previously occurred.
  The brain elaborates an image of what it predicts the eyes should see.
  This information is conveyed from the brain to the eyes, through intermediate stages.
  If a discrepancy is revealed between what the brain expects and the light arriving into the eyes, only then do the neural circuits send signals toward the brain.
  So images from around us do not travel from the eyes to the brain—only news of discrepancies regarding what the brain expects do.
  
  The discovery that sight functions in this way came as a surprise.
  But if we think about it, it becomes clear that this is the most efficient way of retrieving information from the surroundings.
  What would be the point of sending signals toward the brain that do nothing but confirm what it already knows?
  Information technology uses similar techniques to compress files of images: instead of putting into the memory the color of all the pixels, it stores information only on where the colors change.
  That is less information, but enough to reconstruct the images.
  
  The implications for the relationship between what we see and the world, however, are remarkable.
  When we look around ourselves, we are not truly “observing”: we are instead dreaming an image of the world based on what we know (including bias and misconception) and unconsciously scrutinizing the world to reveal any discrepancies, which, if necessary, we will try to correct.
  
  What I see, in other words, is not a reproduction of the external world.
  It is what I expect, corrected by what I can grasp.
  The relevant input is not that which confirms what we already know, but that which contradicts our expectations
  Carlo Rovelli's HelgoLand Chapter VII.

• In the words of the nineteenth-century French philosopher Hippolyte Taine, we can say that
  “external perception is an internal dream which proves to be in harmony with external things;
  and instead of calling ‘hallucination’ a false perception,
  we must call external perception ‘a confirmed hallucination.’”

Veritas Aequitas wrote: ↑Wed Dec 15, 2021 6:25 am Here is something interesting to ponder.
From Carlo Rovelli's HelgoLand.
"the signals do not travel from the eyes to the brain; they go the other way, from the brain to the eyes."

Views?

Veritas Aequitas wrote: ↑Wed Dec 15, 2021 6:32 am Rovelli wrote;

• In the words of the nineteenth-century French philosopher Hippolyte Taine, we can say that
  “external perception is an internal dream which proves to be in harmony with external things;
  and instead of calling ‘hallucination’ a false perception,
  we must call external perception ‘a confirmed hallucination.’”

henry quirk wrote: ↑Sat Jun 26, 2021 3:51 pmThe world exists, exists independent of us, and is apprehended by us as it is (*not in its entirety but as it is). We **apprehend it directly, without the aid of, or intervention of, [insert hypothetical whatsis] and without constructing a model or representation of the world somewhere in our heads.

*If you take into account perspective (where the observer stands in relation to the observed); intervening, inconstant, possible, distortions (water instead of atmosphere, for example); and the inherent limits of the observer himself; then what is seen is as it is.

**Direct realism, of course, is not just about sight. Hearing, taste, smell, touch: the entire interface of a person, as he's in the world, is the concern of the direct realist. That's why I define it as I do. Apprehension covers it all, the whole of a person's direct contact with the world.

Sculptor wrote: ↑Wed Dec 15, 2021 12:50 pm

Veritas Aequitas wrote: ↑Wed Dec 15, 2021 6:25 am Here is something interesting to ponder.
From Carlo Rovelli's HelgoLand.
"the signals do not travel from the eyes to the brain; they go the other way, from the brain to the eyes."

Views?

Whatever the merits of talking about the anticipatory quailities of perception, and they do exist, it is hard to take a post seriously when it launches with a idea which is both absurd and empirically demonstrably false.
All signals travel from the eyes to the brain where seeing happens.
There has been serious and interesting work studying witness accounts which draw attention to significant limitations to accuracy in perception worthy of thought and discussion.
Analogies drawn from "illusions" are also very useful to show how our perception is a construct.

Terrapin Station wrote: ↑Wed Dec 15, 2021 12:56 pm If we can tell that particular brain/nervous system/eye events are "the brain expecting to see something and elaborating an image" then what the hell is all of this debate re whether we have explained consciousness? We've apparently solved it already (at least insofar as we can say that x, y, z brain events are identical to 'elaborating an image' for example).

henry quirk wrote: ↑Wed Dec 15, 2021 3:13 pm

henry quirk wrote: ↑Sat Jun 26, 2021 3:51 pmThe world exists, exists independent of us, and is apprehended by us as it is (*not in its entirety but as it is). We **apprehend it directly, without the aid of, or intervention of, [insert hypothetical whatsis] and without constructing a model or representation of the world somewhere in our heads.

*If you take into account perspective (where the observer stands in relation to the observed); intervening, inconstant, possible, distortions (water instead of atmosphere, for example); and the inherent limits of the observer himself; then what is seen is as it is.

**Direct realism, of course, is not just about sight. Hearing, taste, smell, touch: the entire interface of a person, as he's in the world, is the concern of the direct realist. That's why I define it as I do. Apprehension covers it all, the whole of a person's direct contact with the world.

• 1. Reality is all-there-is [including you, me, world, universe, whatever].
  2. Since You [& all individual humans] are are part of reality i.e. all there is.
  3. How can 'you' be independent from 'all there is' which you are intricately part and parcel of?

Veritas Aequitas wrote: ↑Thu Dec 16, 2021 4:46 am

Sculptor wrote: ↑Wed Dec 15, 2021 12:50 pm

Veritas Aequitas wrote: ↑Wed Dec 15, 2021 6:25 am Here is something interesting to ponder.
From Carlo Rovelli's HelgoLand.
"the signals do not travel from the eyes to the brain; they go the other way, from the brain to the eyes."

Views?

Whatever the merits of talking about the anticipatory quailities of perception, and they do exist, it is hard to take a post seriously when it launches with a idea which is both absurd and empirically demonstrably false.
All signals travel from the eyes to the brain where seeing happens.
There has been serious and interesting work studying witness accounts which draw attention to significant limitations to accuracy in perception worthy of thought and discussion.
Analogies drawn from "illusions" are also very useful to show how our perception is a construct.

Rovelli referenced
132. See, for example, Andy Clark, “Whatever Next? Predictive Brains, Situated Agents, and the Future of Cognitive Science,”
Behavioral and Brain Sciences 36 (2013), 181–204.

I believe your thinking here is a bit outdated.

The truth is the signals travel both ways in different parts of the brain.
In this case, 'eyes' do not mean the external eyes but rather the visual cortex in the brain.

Veritas Aequitas wrote: ↑Thu Dec 16, 2021 4:48 am

Terrapin Station wrote: ↑Wed Dec 15, 2021 12:56 pm If we can tell that particular brain/nervous system/eye events are "the brain expecting to see something and elaborating an image" then what the hell is all of this debate re whether we have explained consciousness? We've apparently solved it already (at least insofar as we can say that x, y, z brain events are identical to 'elaborating an image' for example).

Not sure of your point.
The OP is about 'How do we see' not about 'consciousness' per se.
The point in the OP do not solve the 'hard problem of consciousness' at all.

Terrapin Station wrote: ↑Thu Dec 16, 2021 11:16 pm

Veritas Aequitas wrote: ↑Thu Dec 16, 2021 4:48 am

Terrapin Station wrote: ↑Wed Dec 15, 2021 12:56 pm If we can tell that particular brain/nervous system/eye events are "the brain expecting to see something and elaborating an image" then what the hell is all of this debate re whether we have explained consciousness? We've apparently solved it already (at least insofar as we can say that x, y, z brain events are identical to 'elaborating an image' for example).

Not sure of your point.
The OP is about 'How do we see' not about 'consciousness' per se.
The point in the OP do not solve the 'hard problem of consciousness' at all.

What would we mean by expecting, elaborating and even seeing where we're not talking about consciousness?

henry quirk wrote: ↑Thu Dec 16, 2021 3:00 pm the fact is your body is connected to everything in the world in terms of gases and energy.

more accurate to say I need those gases, that light, that heat, to live, and am permeable to them

All the elements in your body could have been replaced by elements from other humans and things and your old elements are taken up by other things.

this happens already

my substance (flesh and bone) is in a constant state of replacement, and still I persist

sumthin' of me persists no matter how much matter is swapped out

So there is no way you are independent of the world in this sense and the only independence you claim is merely your thinking it so.

sumthin' of me is absolutely independent of the world or I wouldn't be me over the course of time

How can 'you' be independent from 'all there is' which you are intricately part and parcel of?

where you see connection I only see co-existence

Contemporary direct realists may still claim to be defending the notion of direct perception in a sense which is independent of our scientific understanding of the perceptual process.
But such a defence would be the equivalent of getting off a drink-driving charge on a legal technicality whilst admittedly drunk at the wheel.

The verdict may be in accordance with statute, but we wouldn’t want the accused driving the school bus.
Nor would we want a theory of direct perception which was defended on merely technical linguistic grounds driving our worldview.
At stake is no less than our understanding of this world in which we find ourselves, and our place within it.

https://philosophynow.org/issues/146/Ag ... ct_Realism

Sculptor wrote: ↑Thu Dec 16, 2021 5:29 pm

Veritas Aequitas wrote: ↑Thu Dec 16, 2021 4:46 am

Sculptor wrote: ↑Wed Dec 15, 2021 12:50 pm Whatever the merits of talking about the anticipatory quailities of perception, and they do exist, it is hard to take a post seriously when it launches with a idea which is both absurd and empirically demonstrably false.

All signals travel from the eyes to the brain where seeing happens.
There has been serious and interesting work studying witness accounts which draw attention to significant limitations to accuracy in perception worthy of thought and discussion.
Analogies drawn from "illusions" are also very useful to show how our perception is a construct.

Rovelli referenced
132. See, for example, Andy Clark, “Whatever Next? Predictive Brains, Situated Agents, and the Future of Cognitive Science,”
Behavioral and Brain Sciences 36 (2013), 181–204.

I believe your thinking here is a bit outdated.

The truth is the signals travel both ways in different parts of the brain.
In this case, 'eyes' do not mean the external eyes but rather the visual cortex in the brain.

So you dont even know the meaning of the word "eye" and my thinking is out of date?

Please indicate, specifically what is not true about what i said!