There are an incredible number of recurrent top-down connections in your vision processing areas. You do not really see what's there in any meaningful way. What you see is heavily conditioned on what other modules of your brain "expect" to see.
Consider foveated vision. The idea that you can actually see what is going on on your desk all at the same time is an illusion.
Now explain how that's different than anything you look at.
- Your visual system only has access to the 2D geometrical properties projected on your retina. The properties are correlated across images, inexplicably. (I certainly cannot explain how chairs are, in a fashion that includes all chairs I've encountered and excludes anything I've encountered that is not a chair)
- Any other interaction is also a correlation.
- Humans don't have access to the laws of physics, just reasonable approximations in certain contexts.
I see it, but it doesn’t feel optimal. What my brain is telling me I see is different from what I know is true about what’s on the screen. It seems to be interpolating between nearly and actually overlapping with each alternating stripe.
There are a lot of ways it’s optimal to be able to approximate and fill in details like this with normal visual processing, but literally not being able to unsee falsehoods (and I can’t switch it off in my brain like another commenter said they could) doesn’t feel like one of those optimal scenarios to me.
Well yes. You just have to focus on one particular spot to see it, rather than listening to the gestalt-spiral your visual centers are trying to reconstruct (but which isn't actually there).
A little while ago I watched a series called The Brain with David Eagleman and one thing that really stuck with me was how the eyes and brain interact.
The eyes are not connected straight to the main brain, they feed into a 'frame buffer' which creates an image. The brain then looks at what is in the 'frame buffer' and can also add/feedback into it.
This is partially why psychosis can seem so real. One part of our brain feeds into the 'frame buffer', the other part of the brain interpreting what you see can't tell the difference between input from the eyes and feedback from the brain. Those spiders you are seeing are as real to you as if you really do see them with your eyes.
This also goes some way to explaining how the 'gorilla walking through the basketball game' illusion works and other visual tricks such as not seeing the blackout when your eyes move - you really didn't see that cyclist etc.
(I've explained that in my simple language from recollection as it's how I easily understand it.)
One of the great dangers of brain research today is that as we find the "explanation" for things, we will conclude they are just illusions and not real.
Well, the thing is, we're pretty sure at this point then that everything is "an illusion", by this standard. Religious experience, love, red, pain, it's all just an illusion brought on by neurons firing in certain patterns, right? Moving into the computer realm, the text box I am typing this into is an illusion brought on by clever programming, as is the browser. It's not an isolated series of claims of illusoriness, you need to consider the whole of them at once, including not just the politically popular ones (religion), but everything that argument makes sense for (red, mathematics, scary).
I submit to you that this view, while popular, is silly. How can everything be an illusion? That stretches the meaning of "illusion" beyond sensibility. I propose to you that the "illusion" is in fact the real thing, and what you considered reality was in fact an illusion brought on by your ignorance of how things truly work. Finding a neural explanation for an experience does not make it illusory, it merely brings it into the fold of things you partially understand, displacing your previous ignorant ideas about what is "real".
Failing to take this view is, IMHO, extraordinarily dangerous to yourself.
This text box is not an illusion. It is a text box in every way that matters. I send it keystrokes, it puts up text, you read it later. What more do you want? Red is not an illusion. It impinges upon my eyes, I see it and process in certain characteristic manners, all of which are every bit as real as anything else.
Higher levels of organization are not "illusions" merely because they are not atomic. My car is made of nuts and bolts and fabric and metal, and it is those things, profoundly, but it is also a car. My brain and self is made of neurons and glia and blood flow and individual firings, but it is also my self, nevertheless. My text box is no less real for being built twenty layers deep on various more atomic APIs.
To apply this directly to a contentious point, establishing the neural location of religious experiences does prove or disprove them any more than establishing the neural locations of "pain" proves pain isn't real. To disprove a worldview, you need to use logic of the form "Given your worldview, this fact about the world conflicts", and "I found your religious experiences in the brain" doesn't fit that mould. Christians, Muslims, and other religions with creator gods will claim that the creator god put the circuits there because they tap something real. Hindus may not claim a creator god put it there (I know less about Hinduism), but they will still claim it is there because it taps something real. And so on, for many religions.
I'm not saying this disproves the atheistic, Darwinistic view of religion the "I found the neurons" discovery engenders for such people. I'm saying it doesn't disprove most religions to any greater extent, either; it's basically null evidence on that front.
(And heck, while I'm making controversial statements, may I also add that IMHO this viewpoint very nicely harmonizes the traditionally disparate "Western" and "Eastern" views of the world, and that they not only need not be at loggerheads but actually fuse into something quite nice.)
This clicked with me when I watched The Brain with David Eagleman [1] on BBC a little while ago. I've always know there is a disconnect between reality and what you interpret but the way he described it stuck. Note this is my layman's way of describing how I understand it.
Firstly your eyes are not connected directly to your "brain". You don't see what is in front of you.
Your eyes write a rough scan of elements of what is in front of you to a "frame buffer". Your brain looks at this "frame buffer" and interprets what it thinks you are seeing. At this stage it can fill in blanks and do all sorts of manipulations to make it look smooth and complete.
What can also happen is your brain can write to this "frame buffer", this is indistinguishable from the information the eyes have put there. This is pretty much how psychosis works - those monsters/spiders/people/objects seem as real as if they are there.
You cannot perceive anything without your brain processing it. That amount of time is on the scale of 250ms for sight.
Further, the reality you perceive is not True reality, your brain is encoding the information it receives and shows you an evolutionarily successful version of reality.
You can only perceive your surroundings by creating a mental representation of it in your brain. Part of that mechanism involves memory.
Your brain is not immune to the problem, it's just hard to automate the creation of optical (and audio, and presumably all other sensory) illusions when we don't have a synapse resolution connectome of the relevant bits of your brain.
Examples include That Dress, duck-or-rabbit, stereotypes, "garden path sentences", and most film special effects.
I was able to see it b+b when I first woke up this morning. Last night I only saw w+g. But, no, it's not the screen. Two people looking at the same screen will see different things.
The lesson here is that while there is an objective reality, our minds do A LOT of post-processing on our sensory input without our knowledge, so we don't have unfettered access to it.
Nope. You can “see” all kinds of things that aren’t there, because
your brain has yet to notice anything forcefully telling you otherwise. This happens all the time and you’d have no way to notice it.
Even when some new information forcefully comes into play, your brain is often able to adjust your memory so you believe you knew it along, so long as the initial percept is fresh enough and had enough uncertainty.
All of this feels to you like a perfect unbroken stream of direct seeing but it is an illusion. You don’t see anything directly, you get fuzzy spurts of probability and turn it into your world in your mind. A world that’s likely to be unrecognizable to the next person.
It seems likely to me that “seeing things” is consistent with the predictive processing model from cognitive neuroscience. To summarize: the retina error-corrects a simulation provided from the cortex.
Let’s say some visual details are fuzzy.
With a strong enough Bayesian prior (e.g. belief in UFOs), the human perceptual apparatus could subjectively see things that look like UFOs.
Mind bending, but this seems to me a credible and popular theory of brain functioning. I’m no expert and new to the theory. Please correct me if I’m butchering it.
P.S. Like anyone, I often detect motion in my peripheral vision without much detail. Maybe once a year (or less), I see weird things that seem implausible, but only for brief instant. When I look, there is nothing unusual. Yes, bring on the “what are you smoking?” comments… but I assure you the answer is “nothing”.
Yes! I’m confident this isn’t an original thought, but I feel like it’s a dream generator. Things that aren’t quite right but are in some way, perfectly contextually and topologically valid. Like it’s tricking the object classifier in my brain with a totally unrealistic thing that my brain is ready to simply accept.
There’s some image I see on occasion that’s 100% garbage. If you focus on it you cannot make out a single thing. But if you glance at it or see it scaled down, it looks like a table full of stuff.
To make matters worst, what you see with your open eyes, is not one image, is a collection of images with all kind of distortions, blur and other smudges that your brain "photoshop" away to produce an image that conforms to the flawed/bias criteria that your brains considers to be a good image. The same happens with your ears and your taste buds. Reality in our brains is pure poetry.
Citation needed on this: but from what I understand, the way your brain processes vision is that some of what you "see" is in fact the past. The visual cortex keeps recently seen things around and the incoming visual information is mixed with the past images to create the present (almost like compression in a video). Thus it would make sense that after staring at the green lines for awhile your brain is using past information when looking at new lines and hence the illusion.
Consider foveated vision. The idea that you can actually see what is going on on your desk all at the same time is an illusion.
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