The Walls of Experience

Let's start bearing in mind that the main intention of this is to understand the nature of what we humans call reality. It might seem weird to encourage something like that, after all, reality is not something that we can grasp and examine easily. If we dip into it, we could rapidly conclude that reality is the "phenomena of phenomena", in other words, it encompasses quite everything we can know and experience.

Even, by definition, reality also includes the things that we ignore, but that's pretty much of an inference that we tell ourselves as we tend to believe that there's always something left to discover, even though we can't have a single clue about anything that lies beyond the boundaries of our current knowledge. These sorts of arguments are related to what's known as "epistemology", which can be reduced into a fancy question: How do we know what we know? It might sound simple, but it's far from being an easy task, the pursuit of justifying knowledge is a rough path, that demands extensive self-reflection and introspection.

We know that the world is made of atoms, but are we sure of that? We can't see them, I mean, we can't access them through our conscious experience, but we can suppose their existence through reason, once we start to think in terms of a larger world beyond our senses we start to expand the size of our knowledge. So then we begin to furnish the walls of our mind with the stuff that we learn and assume is true. But let's start from the beginning, this hasn't been this way since always, our ancestors weren't always aware of the atoms, the DNA, the wavelengths, or the most far away galaxy from us.

The most basic source of knowledge that we humans can have is our conscious and subjective experience, which by its mere observation we can conclude is finite, it has a lot of gaps and ends, and it is almost like a bubble. It hasn't changed so much since we were just hunters and gatherers, and you, dear reader, are in the same condition as every single human that has existed or exists right now. You are inside your own "bubble of experience", and as I said before, it's the same for all, even for the most "objective" scientists.

If we take this seriously, we can reach the amazing conclusion that the Universe is the same size as our knowledge and imagination. I acknowledge the existence of atoms, I'm not an anti-atom person or anything like that, but I also recognize the limitations of what I can know. I can see my hand and imagine the atoms that compose it, but that's something that I'm rendering in my head. The atoms, the galaxies, and the DNA are pictures in my mind, which represent aspects that I don't simply have access to.

We can be sure of modern scientific knowledge because it fits with the observations and phenomena that appear within our experience of the world, and this is how science works after all. If we analyze the history of the atomistic models that have existed, we can realize that we are dependent on constantly updating our knowledge, to get even closer to an ultimate reality that is simply beyond our human limitations. I know Andromeda's Galaxy exists, although I have never seen it, every time I look at the night sky, even if it appears as a pure black dome over my head because of the light pollution in the city I live in, I can imagine it there, in its same glory as the 720p image that I once download from google.

So I emphasize the point that I made before, about the Universe having the same "shape and size" as our individual knowledge, imagination, and past experiences combined. It is not a surprise that something as subjective as our mood can render how the world seems to us, whether we consider it a friendly place or a threatening one. Returning to the main topic, it is weird to realize that the world of our conscious human experience almost seems like some sort of simplified depiction of the descriptions that modern science offers.

The features and properties of the world of human experience seem almost detached from the things they are associated with. For example, phenomenal colors are thought to be associated with what modern science describes as different wavelengths within the electromagnetic spectrum. We have models of how these types of waves might look like, and the way they travel through the physical space, although we don't see this within our conscious experience, at least explicitly, what we see instead is a qualitative and recognizable feature covering a certain area or volume within our visual field, whether it is in the form of a shape or an object. This property of conscious visual experience seems to appear beyond our phenomenal eyes, outside fixated in space, along with the objects and stuff we commonly see around us.

This is what is known in certain areas of psychology and philosophy as "Qualia", which can be defined as the "way in which things appear to us", the way experience presents itself in its more basic form. If we think about it, qualia is the substance from which our familiar existence is made, without qualia our experiences would be empty, literally, in the same way one goes to sleep and the world seems to disappear. Returning to the last example, some people would argue that that's just the appearance of those electromagnetic waves, but it doesn't reveal its "true form" which is what science studies.

Nevertheless, if qualia didn't exist there would be no way to confirm the existence of these phenomena because the first step to study phenomena is to notice them through direct experience. The first level of the scientific method is observation.

Things have to make themselves present within the apparent world, otherwise, they would remain hidden —the things that exist independently of our conscious experience are known in philosophy as "noumena"—. Then, we could easily conclude that conscious experiences have an intrinsic value that we can't ignore at all. Colors are just a type of qualia, a visual one, as you might have inferred, there's other kinds of qualia as well, such as auditory qualia, scent qualia, bodily sensations which are also qualia, and the list goes all the way down. Based on this, we could say that qualia functions as a measurement unit for conscious experiences, relying on the noticeable differences that one could be aware of just by examining any moment of experience. So, from this moment I want you to bear in mind that whenever I mention the term "consciousness" I'm referring to qualia. It is a concrete definition that works well for the sake of this blog.

Returning to the topic, we can also conclude that qualia is the thing that renders the world we experience, as well as other aspects of the subjective bubble each of us inhabit independently, things that only ourselves can be aware of, such as thoughts, emotions, memories, and mental images. Each of us has a private set of these. Our individuality prevents us from taking a look into other's bubble experiences, so we can't be aware of the "inner virtual environment" of others.

As I mentioned before, these qualitative features seem to coexist in such a sophisticated way that give rise to the scenes and recognizable wholes that we regard as the "semantic contents of our experience", such as in the form of any daily life scene of ourselves in a solid and stable world. Returning to the main premise: "The world we experience is made of qualia". It almost sounds weird to make such a statement, at least in the way I just put it. It might look like I'm talking about this as if there were these fundamental blocks called "qualia" that build up the things we see around us, almost in the same way pixels work on a screen to generate recognizable images. Some others would argue that that's impossible, almost pointing it out as absurd, that there are no such things as qualia, the world of our experience is not made of any "qualia", it is made of matter, waves, and similar stuff; the Universe is built upon those things and our experience is just the way the world —as it is, in all its glory— looks like! "I can feel my body, but it is not made of "body qualia", that's nonsense, instead, it is made of DNA, compounds, cells, tissue, and organs. I can't feel my liver, but it doesn't mean it's not there!" Then I would ask: "If I can't feel none of those things, then am I really having direct access to my own body? Is the body I experience the same thing as the intricate and complex sum of morphologies that modern science defines as a body?"

If the world of our experience ends up being the same as the objective world that science describes, then, why do some features of it seem so arbitrary? As I mentioned once in my last Ontology, the experience of the world we have fits very well with our behavior, almost as if the world were adapted to us, instead of the opposite, and this has probably something to do with our condition as biological creatures that seek for survival and replication.

A creature of this nature just needs to be aware of the things that could be useful from an evolutionary standpoint. This would explain why the size of our phenomenal world is finite, like a bubble, also with a limited image resolution, this means that its capability to contain details is limited, so there are no atoms encoded implicitly in the visual experience of objects we have. The table you see exists just as it appears. Letting alone the strange fact that we have a proprioceptive and kinesthetic dimension embedded in our conscious experience, which is almost a significant part of it; we can feel our bodies in such a sophisticated way, but where does that come from? How a complex arrangement of biological systems can be "aware" of themselves as a unity? All of these questions might sound odd, but it's because they are formulated with the wrong paradigm.

The fact is that the experience of the world we have and the objective world described by science are not the same entity at all, they are detached, but I'm not saying that conscious experiences are a mystery nor do they reside beyond our scheme of how things work, actually consciousness can be well-described by the language of modern science, the initial concern was that we are not addressing the problem in the right way.

We are mistaking the objective reality for the phenomenal one, and I'll explain why that is the case. Before I get into that, I want to introduce the concept of phenomenology, because it is a term that is going to be recurrent throughout this lecture.

Phenomenology is considered a method to understand the structure and properties of conscious experience, without taking into account the assumption of an "external world", rather it tries to make sense of them by just describing their appearance, only relying on the way experience presents itself.

Illustration that depicts the phenomenology of a moment of visual conscious experience. By Ernst Mach (1886).

It also can be an useful tool to identify features of them that don't seem to correspond with aspects of the external-physical world. It is quite useful when we are dealing with things such as: Illusions —examples are many—, hallucinations, altered states of consciousness, dreams, and more similar phenomena, which can't be understood in terms of an "external world", but by the implicit mechanics of subjective-experience instead. Also, the very existence of these phenomena gives us an important hint to understand how perception actually works. There's also an adequate analogy to this, which I first heard from Andrés Goméz Emilsson —Co-founder of Qualia Research Institute—, and it goes something like this, think of our common daily human experience as the room temperature of consciousness, so depending on whether I increase or decrease the temperature of the room, the features and properties of the experience will change as a consequence of this, similar to what does happen to some materials when are exposed to rather high or low temperatures.

Therefore, we could infer that consciousness is something that can evolve in ways that can be described and hence predicted.
Now, let's take the first step to understanding what perception is. How is it possible that we can be aware of the things that are around us? As you might already have noticed, the main plot of our conscious experience is about being these sort of creatures that work under certain constraints to sustain themselves, these creatures move, react to their environment, they look for sources of energy, by digesting organic matter and expulsing what is no longer necessary, they also get inactive for a while to achieve some sort of biological benefit, and so many other interesting things, and I'm obviously talking about a big part of our daily routine, doing whatever we do, eating, going to the bathroom, and sleeping. It is quite clear that we are not mere spectators who just casually got a fancy window to the world.

Perception has a purpose, which is behavior; to convert stimuli into responses. And let me tell you that perception is one of the most bizarre phenomena in the whole Universe. Before I move towards that part, we should know the difference between two alternative ways of thinking about perception, I'll figure out which of them is closest to be true, based upon evidence and speculation.

I'll start with the most intuitive, which is also naively accepted by most people, this one is known as the "direct theory of perception", which defends the idea that we are capable of directly perceiving what's around us, so it assumes that we experience the world as it really is, therefore implying that there's not an intermediate process required to have an experience of the world around us. From the point of view of direct realism, the world of our experience exists beyond our sensory surface, where it's independent of all the "perceptual machinery" that is supposed to be involved in our human physiology. In other terms, direct realism suggests that the visual experience we're having right now is not a picture on our retina nor a fancy perceptual replica residing somewhere inside our head, but a fixated and all-encompassing volumetric structure surrounding us that extends even beyond what we can be aware of at the moment, which also includes color, hue, shadows, and whatnot, as if these were intrinsic features of the world itself. To make it sound even more assertive, we could add the other features of our common experience that are left, such as sound, taste, or scent. According to this model, all of those characteristics of experience exist independently.

Then, we could infer that direct realism takes too seriously the dualism between subject and object, which is not something wrong, there has to be for sure an objective reality detached from us, which stays in the same way even when we are not there to perceive it, BUT, direct realism fails for assuming that the world of conscious experience and the objective world are the very same thing. So, under this logic, it doesn't matter at all if there are no people around to be aware of the events of this world because according to direct realism, things always exist in the same qualitative way we experience them when we are present.

So, it doesn't matter at all whether we are there or not to be aware of things. If a tree falls in the middle of a deserted forest, it still produces a sound, even when no one is around to hear it. An apple stays red and sweet, no matter if we are not there to see it or taste it. A scent would always smell good even if there's no one to confirm it. If we dip down even more, we'll promptly realize that there are a ton of gaps and flaws with this model. There is a set of things that easily would put this "pseudo-hypothesis" in doubt, known in psychology and neuroscience as the phenomena of perceptual variance, meaning that the world might appear different from the subjective experience of some people, implying that the world is not exactly the same for everyone.

One example of this is color blindness, in which people who have this condition are not capable of experiencing colors the same way a "typical person" would do, in other words, if we were able to compare individual phenomenologies which contents were, in theory, the same scene, one from a color blind person and then another from someone who is not, and let's say, for example, that the scene in which both experiences coincide is about a tomato over a desk, after contrast, we would promptly realize that each experience has its own type of red, although the scene is exactly the same. How is that possible? If we take naive realism seriously this would be impossible because it assumes that color is an intrinsic feature of the world itself, and therefore it has to be the same for everyone, but the truth is that that doesn't happen. A most extreme case of perceptual invariance is synesthesia, which is an incredible phenomenon because it messes with the nature of each sensory modality we humans have.

Some people with certain types of synesthesia report either experiencing colors or shapes in the presence of auditory stimuli or sounds in response to visual stimuli, like hearing a specific tone whenever they stare at something green. Also, some others can experience scents or even flavors while reading or listening to certain words. It is a well-documented phenomenon and it is usually used as a common argument against direct realism.

Direct realism assumes that the senses are somehow capable of providing us with the truth, which is an idea that easily can be put in doubt as I have just demonstrated with the last example. Besides, it is ironic that the "direct theory of perception" doesn't even bother to give a satisfying explanation of how perception works, instead, it assumes that the world is just there in all its glory, ready to be experienced, and our senses are analogous to windows. So, everyone has their own "window" from which they gaze at the world.

I personally find this odd, it sounds almost magical. It might not be a good answer, though it points out something very fundamental, which is the fact that —phenomenologically— the world appears to be that way. It is actually the most naive way to think of it. But as I mentioned before this might lead to bizarre ideas that don't have almost any fundament. One example of it is the concept of "Cartesian theater", introduced by Daniel Dennett, it proposes that we have some sort of miniature observer inside our heads, which is somehow the cause of why we can experience the world, then the idea of the "senses as the analogous of windows" may sound convincing, where the eyelids are almost like roller blinds for the windows that our eyes are, which work as a way to occlude the sight to our inner observer. According to this fairy tale idea that's why the world seems to disappear, but it emphasizes that the world actually doesn't go anywhere, it is always there.

This illustration represents the gist of the Cartesian theater idea in an almost cartoonish way. Still, it points out the problem of trying to localize where the source of awareness and experience might reside. In other words, it tries to answer the question of what and where is the thing that makes the world experienceable. Nonetheless, as I said before, this argument is relatively primitive and outdated, as it is inferred from Rene Descartes's hypotheses.

We can see that direct realism is stuck in some sort of limbo because it accepts some phenomenological facts, but then rejects other ones when it's convenient, almost without any deep reason or consideration.

Trying to make sense of how senses work has been a recurrent topic throughout human history, and it is quite disconcerting to know that the most familiar aspect of our existence has been also one of the biggest mysteries since we started to ponder over the nature of phenomenal experience. For example, the ancient philosopher Plato thought that there was some sort of radiation coming out from the eyes, projected onto the world that sensed the things around by seizing them, providing us with direct experience.

Something that I honestly don't understand about direct perception is the role that our senses perform, because according to science, light travels from the world towards both eyes, enters through a focal point, and then gets imprinted on the surface of each retina, where some cells are responsible for translating those photons into electrical impulses that go down through the optic nerve until they reach the brain —precisely the visual cortex—, so they can be processed and finally interpreted. This is known as the causal chain of biological perception, an argument that ends up breaking the logic of direct realism.

According to modern science, our experience of the world is the product of this process, which starts in the senses and ends in the brain, suggesting that the world of our experience is located within the brain since it is viewed as a perceptual representation based on sensory information. For direct realism, all of these premises represent a big problem, because this argument presents two separate entities, on one side, we have the authentic external world, which is the source of the stimuli that reach our sensory surface, while on the other side, behind the layers that cover the brain up, what we have is an internal representation of that extracranial world based on sensory input, which according to modern neuroscience corresponds with the contents of our conscious experience, implying that the world of our conscious experience resides within the brain.

By simply closing our eyes, we can infer that this is the case. The fact that when we close our eyes the world fades out, implies that sensory information is traveling in a one-way direction, which is from the retina down into the brain, so when the retina stops registering stimulation, the visual cortex becomes unable to draw an image subsequently.

This argument also implies that our heads which we know we have through conscious experience, are emulative in nature, as these are perceptual-miniature replicas masquerading themselves as the authentic sensory surface that wraps up our physical skulls.

Direct realists firmly believe that the world we experience is the definitive authentic external world, therefore, they argue, that the world is outside our heads, not the opposite. Direct realists simply can't assimilate the idea that we might be standing in a perceptual replica rendered by the brain. Direct realists assume the world they experience is the world itself, so the world cannot be an image imprinted in our retina, nor a fancy perceptual replica inside our heads, and if that is actually the case, how is it possible that something theoretically located in our retina, not to mention within our skull, just as modern science suggests, can display itself out beyond our sensory surface, where we know our eyes are placed. Isn't that contradictory? Modern neuroscience is telling us that the world is in our heads, but at the same time, our heads appear in the world, enveloped by it. Again, if the world is constructed within our heads, how does it escape the confines of our skulls and appear right beyond our sensory surface? So, what is the appropriate way of making sense of this?

To illustrate this better, there's a common phenomenon that every one of us has experienced at least once in our lives, which usually happens when we stare at a bright light or camera flash. The shape of the light's source gets stuck in our visual field, even though when the stimulus isn't there anymore, no matter if we turn our heads towards another direction or simply close our eyes, the image is still there, lingering for a few seconds or even minutes; this is what is known as an afterimage. It is well understood nowadays that this is caused by an over-stimulation on a limited section of the retina, but the weird thing about it is that the afterimage doesn't appear on the inner surface of our eyeball where we believe it is, but rather portrayed out there in world, in front of us, among with the things we see around us.

This video is an example of it. After staring at the center of this image for a short but sufficient amount of time, the eyes get exhausted which causes the image to linger in our visual field even though the stimulus is already gone. The image presented in the video doesn't resemble anything because at first glance it just seems like a bunch of random shapes, but once you stare at it for a while and look around, the afterimage presents itself as a familiar form, which in this example comes to be the "face of Jesus Christ". The afterimage seems also to become clearer as one repeatedly blinks. As I previously mentioned, the afterimage appears out in the world, as if it were painted on the walls and ceiling of the room one can see around.

If you really think that the world you see is the world itself, then a mere afterimage can represent an anomaly because it is paradoxical through the lens of naive realism. An additional aspect of it is that the picture on our retina is actually inverted, nevertheless, the contents of our visual experience appear right-side up, implying that there has to be an underlying mechanism responsible for optimizing our visual experience. At this point, the problem just becomes more apparent. How can we make sense of the fact that the world of our experience ends up outside of our heads when the evidence clearly tells us it is constructed within them?

At this point, some people would speculate and consider other alternatives to solve the problem, one of these secondary arguments is the projection theory of perception whereby phenomenal experience is indeed a distinct entity from the authentic external world that exists beyond the skull but is not thought of to be contained within the brain, although it doesn't deny their dependence. What projection theory suggests is that the brain expells the world of our experience —which is a product of it— out onto the remote external environment, in such a way that both end up superimposed. In this blog, we ignore this alternative because there's no rigorous evidence about something getting out from the brain, or the eyes. I personally don't believe that our head is some sort of projector.

Hence, if this is not valid either, what is actually going on?

So well, we are carrying a weird fact about perception: Light from the world enters our eyes, where it gets transduced by the cells that constitute the retina in the form of electro-chemical impulses that goes all its way down through the optic nerve until it reaches the occipital cortex of the brain, it causes some sort of activation pattern in it, and at that moment, suddenly, in an almost magical way, the world around us gets automatically generated, popping into existence.

This suggests that the world we experience around us exist as long as the cortex receives sensory input, which results paradoxical if we analyze it from a direct realist standpoint. The brain is supposed to be completely isolated from the external world because it resides inside the skull, where it only has access to electrical signals, however, the world we experience appears to exist beyond the outermost layer of our anatomical structure, far away from the grasp of the brain. Direct realists assume that the world of experience is the world itself, but such a premise would imply the complete absence of any sort of connection between the world of experience and the brain. Nonetheless, evidence demonstrate that the mechanisms responsible for perception and especially experience reside inside the brain.

So, according to this, if I were somehow capable of altering the activity of my brain, then theoretically, such alteration should be reflected in my experience as some sort of apparent distortion. This is not a hypothesis, this actually happens with some drugs, once a substance enters the body, it affects the brain, modifying its inner dynamics, whatever they might be, provoking the astonishing effects that they are known for. Therefore, this gives place to the question everyone might be asking right now, how does this work? How is it possible that a soft and moistened machine inside such a dark and compact place which is our skull, is capable of controlling and affecting the world we see around us? There's some sort of strong causal relation between the world and our brains.

As I mentioned on last occasions, the very existence of illusions, dreams, and hallucinations breaks the logic of direct perception. For example, dreams tend to be not less elaborate than the presumably solid and stable world we experience when we are fully awake. Dreams can also evolve in a coherent fashion, whether in the form of spatial structures or congruent successions of events. We can even interact with dream characters that might portray themselves as people we know in the consensual world of ordinary conscious experience. We are supposed to be nonreceptive to the stimuli of our surroundings during sleep, implying that we can still have rich-content experiences without sensory information. Dreams are epistemologically disconcerting because they allow us to have entire experiences of being in completely different places and scenarios while we sleep, nonetheless, we are supposed to be lying in our beds in the presumably "authentic world of consensual reality". This has to be enough evidence to acknowledge the innate capacity of the brain to fabricate complete synthetic worlds of experience.

This scene comes from the 2006 film "Paprika" and I think it perfectly illustrates the idea of dreams as photorealistic simulators that can render almost anything.

Continuing with that thought, we have the phenomenon of hallucinations. Hallucinations can be defined as the appearance of images, sounds, sensations, and any other property of conscious experience, in the absence of a verifiable external cause. What's interesting, but at the same time disconcerting about these phenomena is that they tend to appear situated in the external world, among the objects we normally perceive around us.

Hallucinations are commonly associated with some psychiatric disorders such as schizophrenia or psychosis, but these phenomena may also occur under multiple circumstances, during hypnagogia, for example, whereby hallucinations are frequently reported, also, drug-induced hallucinations, which are well-documented in psychonautics, and more severe neurological conditions like epilepsy or dementia might trigger hallucinations as well.

As I explicitly depicted in previous examples, it is supposed that hallucinations have their cause in the brain, whenever the inner mechanisms that involve perception get screwed, just as what happens with certain kinds of drugs, however, if we think that what we are seeing is the world as it really is, then this represents an anomaly because from a naive realism standpoint, perceptual distortions shouldn't be possible, but they are.

It's well known that once a psycho-active drug enters the organism it causes a transitory alteration in brain activity, although the true change is happening somewhere inside our head, within the limits of our skull, the effects associated with the drug appear in the external world, among the things that we see around us, out beyond the limits of our sensory surface. Almost as if the world that we experience around us were somehow synchronized with whatever happens inside our brains.

As an example, one of the most popular and well-documented perceptual distortions associated with psychedelic drug intoxication, is known as "symmetrical texture repetition", phenomenologically described as the appearance of dynamic shapes arranged in a symmetric fashion covering every flat surface within the subject's visual field, such as walls, furniture, and even other people's faces, usually more noticeable on those surfaces that have a consistent texture across themselves, such as asphalt and grass, and depending on the dose these can vary in intensity.

This video shows an accurate representation of the phenomenon described above.
This video belongs to the Youtube channel "cartoon mimosa", which is dedicated to replicate the effects of psychedelics and other substances.

This phenomenon is considered as a type of visual hallucination. The inquiry still being the same, how is it possible that something that is supposed to be inside our brains manages to appear right in front of where we know our eyes are?

For someone who has never experienced any sort of hallucination or perceptual distortion, these phenomena may come across as quite unsettling since they appear to have an independent or detached existence from the viewer. This impression might lead us to naively believe that these phenomena have their foundation in the external world since it's where they appear to reside, nonetheless, perceptual distortions don't seem to leave any trace of their existence in the external world where these are reported to be seen, besides that nobody except the subject who claims to "perceive" the distortion can be aware of it.

The Butterfly Effect, 2004. The first time I watched this film I couldn't help but be mesmerized by these scenes in particular, as they fairly depict the private character of hallucinations and altered states of mind, in this case, possibly reminiscent of those phenomenological descriptions attributed to schizophrenia or psychosis.
These scenes point out the private property of hallucinations, whereby the secondary characters cannot interact with the protagonist's hallucinations.

If it weren't for the evidence that perceptual distortions are subjective, many of us wouldn't have a clue about their possible nature. Just as we saw with the case of color blindness and synesthesia, all of this suggests that our experience of the world is private, in other words, everyone lives inside their own "bubble of experience", and the "weather" of a bubble of experience, like its properties, are determined by the brain that is associated with.

We tend to assume that we all live in the same world but this might not be the case. As was suggested by the last analogy, what we only might have access to is nothing but a private perceptual copy of the authentic external world. This replica must be located inside our heads where we know all the machinery that accounts for perception exists. If we continue with this thought we may conclude that perceptual distortions and the world of our experience are not completely incompatible entities as both coexist within the brain. Therefore, distortions can only occur within the world of our experience since it's not the world itself but a replica whose stability depends on brain activity.

Something far less severe is an illusion, though it still is an easy way to demonstrate that we are not seeing things as they really are, therefore, our senses are not as flawless as we thought they were. Illusions are very common and everyone can experience them, they come in many flavors, some static images can generate the illusion of movement, while others can make us see shapes and things when there are not any.

Submerging a stick underwater and seeing how it bends is also an illusion. There are also illusions that we usually ignore, that happens almost everywhere, the phenomenon of reflection is one of them, the fact that we can see fragments of the world portrayed on the surface of some objects, however, we don't spend too much time thinking about it because it is something that our minds learned to deal with and ignore since we were children. Well, this kind of illusion is indirectly caused by the very fact that the source from which vision is based is light, and the way light works in the physical world is also constrained.

If direct realists assume that they see things as they really are, then, they are also wrong in one of the most fundamental ways. According to physics, what we are "seeing" is not matter, but only light that bounces upon it. Once the light is gone for whatever reason, our eyes stop receiving information and everything simply fades out for us. Light is not perfect, some materials are better at reflecting it, so because of that we can have mirrors and fancy optical illusions. Another example is that when light passes through heated air, we can notice the effect that it has on light, which appears in the form of a visual distortion.

This is a feature of physical light that has an explicit presence within the contents of our conscious visual experience. As I mentioned before, it doesn't represent a big problem at all since we learn to ignore it in early stages of childhood, until we grow up and accept it as an intrinsic aspect of the world we live in. Another subtle thing that we humans tend to ignore is the phenomenon of perspective. Things that are far from us appear smaller, almost like miniature figures, and those that are close to us appear bigger, almost occupying our entire visual field. When things are moving farther away from us, they simply appear to constantly diminish in size until they completely vanish.

The thing is that perspective is actually a distortion caused by the optics of the eyeball. The phenomenon of perspective occurs when three-dimensional information collapses onto a surface, in this case the retina, leaving a flat image. As a result, the farthest things leave a smaller picture on the retina, while the closest ones do the opposite, leaving a bigger one, that's the only way something flat can represent depth. However, perspective doesn't exist in the "real world"; perspective is something that only happens on our retinas and the flat sheets of cameras as well.

Things in the physical world are always the size they are and that doesn't change, nevertheless, our conscious experience of the world appears deformed. Therefore, this confirms that the contents of our experience are somehow determined by the structure of our human anatomy; let alone the fact that this only represents the first level of perception, beginning with our eyeballs.

However, the world that we experience appears as a volumetric structure enveloping our phenomenal bodies, there's some sort of depth value that pervades the scene, so it might seem that the world we see can't just be a flat picture on our retina after all, nonetheless, the world of our visual experience also includes perspective which by itself represents a contradiction.

A little comment here is that I'm focusing more on visual experience to unpack these concepts because vision relative to the other senses comes to be the most "reliable source of information" for us, humans, therefore I thought that if I could demonstrate that that isn't the case, it would be easiest to think of the other features of our experience in this exact way, as mere "widgets" developed by the slow process of biological evolution. This idea will make more sense as long as we get deeper into this section of the blog.

Returning to the topic, a stubborn direct realist would be unsettled because the nature of visual experience ends up being paradoxical, from his point of view, the world he experiences is indeed the world itself, although, whatever happens on the retina, not to mention within the brain, somehow finds the way to appear out in the world, just as in the case of afterimages, therefore, if projection theory isn't correct either, how is it possible that something theoretically occurring inside our eyeball appears out displayed into the "external world"?

The complete answer in the words of Steven Lehar —professor in cognitive psychology, and independent researcher—, is the following: "The conclusion that I've reached is that the only way it can get out into the world is because this is not the world itself, all of this that you see is downstream of your retina, and thus, in my view, inside your brain, and you can't see the world itself directly; you can only see it through its visual replica".

An illustration that depicts the gist of indirect realism, in which the world of experience is seen as an isolated and active representation of a remote environment that exists beyond the external surface of the physical body.
Author: Steven Lehar

The thing that Steven Lehar is pointing at is what is known nowadays as the "indirect theory of perception", which is the very alternative and also the most accurate way to address biological perception and its role in consciousness. As you might already infer, this current of thought is the opposite argument relative to direct realism, but in the upcoming paragraphs, I'll explain why both can actually fit very well in the same picture. Before that happens, we should first unpack the concept of indirect perception.

We know that the brain is where all the information that comes from the senses is processed and put together, but there's a little detail of which we should be aware. When the stimuli trapped by the senses get traduced into electrical signals to be sent into the brain, the original nature of the stimuli gets removed, which by itself means that it is being represented, instead of passing cleanly through into the brain to be finally used. The most of perception occurs in the brain, which resides inside the skull, isolated from the rest of the external world. All the senses are complete strangers to each other, and it is the same for the rest of the body as well. All the information sent from each sensory device travels through different pathways to reach the brain. The brain is then responsible for assembling each piece of sensory information into the same moment of conscious experience.

If direct realists were right this shouldn't be necessary because naive realism doesn't take into account that senses are actually intermediates in perception.

If we take a look into our conscious experience of the world, one of the most outstanding properties it has is that it appears as a whole, each sensory modality is displayed simultaneously in the same moment of experience. As it was previously argued, the brain is responsible for assembling all the sensory information that comes from different sources in the form of a unified representation, which is the reason why we can enjoy a complete experience of the world as we commonly do.

Therefore, these "perceptual fields" that simulate different stimuli not only can coexist within the same model but also they can complement each other, leading to the inclusion of implicit features that might be advantageous since these represent important aspects of the remote environment, always relative to the organism. For example, the perceptual copy of the body appears to be contained inside the perceptual copy of the world, as if it were some sort of hamster ball, which results accurate for what's supposed to represent.

Regardless of each eye being separated from the other, our visual experience integers simultaneously both images captured by each eye, hence, the unique way to make these parallel images converge or meet each other is through the brain, same for the other senses. All the information that comes from the external world converges inside the brain in the form of electrical signals.

Then, the brain builds up a representation of the external environment based upon this "sense data", which according to indirect realism, corresponds with the conscious experience of our surroundings.

So, we see the world indirectly, rather than directly, in other terms, we don't experience the world as it really is, but instead, we experience a sophisticated representation of it. Besides our surroundings, the experience we have of our body also corresponds with a "miniature replica", contained in the parietal lobe of the brain's cortex, which in this case, simulates the "authentic physical body". The world we experience is more like a controlled hallucination that's coupled with sensory information triggered by external stimuli.

Our conscious experience of being a human —as we all know it— can be seen as a fancy interface that our brain uses to navigate the world. If we follow this logic, we can get to implications that we might not have considered before. We could rather infer that our phenomenal sense of being a human resembles something more like a "video-game avatar", a synthetic creature that inhabits a virtual world that pretends to be solid and stable, but when we close our phenomenal eyes it vanishes, only to get generated automatically when we open them again.

The world is not getting rendered behind our heads, there's just a void, but once we turn around to look there, that part of the world gets constructed before we even notice. Similar to what happens in some video games to save resources.

We naively tend to assume that the world of our experience has a detached existence apart from us since it doesn't seem to be bothered by our hypothetical absence. Many of us firmly believe that we live in a completely solid and stable world that doesn't cease to exist whenever we're not there to perceive it.

We are commonly confident about the idea that whenever we enter a room, closing the door behind us, the rest of the world doesn't go anywhere, we just infer that it's still there, exactly as we left it, even though we cannot have a clue about it since it's already beyond what our senses can grasp at the moment. Therefore, how can we be absolutely sure that there's not just a void where the "rest of the world" is supposed to be?

Naive realism takes for granted that the world of our experience is nothing but the world itself, suggesting that it doesn't have any gaps, voids, or boundaries, therefore, no location or place is supposed to disappear whenever it's not perceived, even though there's no way to prove so since we can only be aware of those events and places that imply our explicit presence, which represents a hard barrier to our epistemology.

Something not less important to consider is the limited capacity of the senses since these can only grasp a finite area or volume of the environment at a time, leaving what's beyond that field unrevealed. Furthermore and as was argued before, the brain is responsible for rendering a perceptual copy of the remote environment based on the sensory information that's available, therefore, whatever is missed by the senses cannot be explicitly represented nor included within our private world simulation.

Although there are many gaps and blind spots distributed across the sensory representation we inhabit, the brain has found sophisticated alternatives to deal with missing information. Our world simulation also includes low-level representations based on predictions, so it's not necessary to rely solely on what the senses can provide. The representation that's coupled with sensory information exists as an explicit structure within our experience, exhibiting a sturdy and stable appearance, also capable of maintaining permanence in detail, while the things that lie beyond the grasp of the senses are rendered implicitly, as hypothetical percepts.
Author: Steven Lehar

Similar to what occurs in most video games, there's no use in rendering the whole virtual world at once since the player can only experience one limited chunk of it at a time as it wanders around. Rendering the entire world would be unnecessary and expensive, instead, what's only required to be rendered is what the player can perceive in all directions at one particular time, so you're giving it the illusion that it has full access to an entire world when it's not. The things that are beyond the grasp of the "sensory field's" player do not exist since these are not getting rendered at all.

Certain properties such as perspective make this task even easier since there's a limited resolution in every visual scene, the things that are far enough from the viewer decrease in such phenomenal size that can be replaced by smaller and simpler models if not mere images. Some video games even use flat backgrounds or GIFs to simulate things that are pretty far from the viewer, such as the horizon, the sky, or distant mountains, which is quite funny. Also and not less remarkable, things that are occluded by other objects don't need to be fully rendered since these are out from the visual field's player.

Therefore, the "world" with which the player interacts resembles a bounded bubble enclosing it.

What's interesting is that the brain seems to use similar techniques and shortcuts to render and optimize our world simulation. After all, the motivation of video games has been always to fairly depict the features and properties of human experience. This quest for simulating what's more familiar to us has led video games to unintentionally discover the mechanisms behind the mind.

Other kinds of arguments seem to have a solipsist nature. Based on the assumption that if we cannot experience the world directly but only a private representation of it, then this should also apply to the experience of coexisting with other humans and living beings, implying that these are also simulated by the brain through replicas that don't include a subjective experience of their own. So does this mean that I'm sharing my private world simulation with philosophical zombies? Indeed, but as far as we can tell this is only a consequence of how our brain represents the external world, thus, we can think of it as an intrinsic feature of world simulations. Hypothetically, you also exist as a "zombie" inside the world simulation of everyone else. This idea resembles the modern concept of "NpCs", introduced by video-games, referring to virtual machines that look and behave as an authentic human would do, but which are devoid of any sort of subjective experience or "internal movie".

Strangely, these kinds of arguments have a lot in common with what we have been hearing about modern philosophy nowadays, which I suppose has been influenced by cultural events, like the enhancement of computers and the quality of video games, also by released films such as The Matrix or The Truman Show. I think all of these are hints, pointing to the same thing that is begging to be noticed, the way the human mind really operates, which also unveils the mechanisms that sustain our familiar existence.

For example, the main plot in the film The Matrix is that all of humanity is trapped inside a simulation, without knowing they are, because "the machines" found a way to fool their brains and make them believe they are living an ordinary human life, while they are actually encapsulated and connected to all sort of bizarre machinery without a single clue of it.

This illustrates a popular concept in the philosophy of mind, known as "brain in a vat", a mental experiment that conveys the idea that a brain is by definition capable of generating a complete experience of being a human, even if this is separated from the rest of the body and the senses, based on the assumption that experience is a product of the brain, then if we were able to know exactly how this works, we would be able to simulate experiences from scratch, without needing any "real stimuli". In one of the most iconic scenes of the movie this arguement is presented, when Morpheus is explaining to Neo what the Matrix is, he mentions that everything Neo experiences is in reality a mere bunch of electrical signals interpreted by his brain.

The Matrix, 1999. This film presents what I would call a sophisticated version of the already mentioned thought experiment "brain in a vat".

The brain cannot really tell the difference between whether those electrical impulses come from a "real external world" or from a mere computer program. This means that it doesn't matter the nature of the stimuli, whether is authentic or emulative, because the world we experience ends up always being a simulation generated inside our brain. So, this is the main premise of indirect realism. We are not in the real world, instead, we are inhabiting a "world simulation", rendered by the most complex machine in this known universe, the brain.

There's a fundamental component that brings this concept to life. As I have described on different occasions, rendering a mental picture of these concepts is essential. Many scientists and intellectual people accept indirect perception, the assumption that experience is created somehow inside the brain, after all, science has been grasping this since a long time ago, so for them, this is not such a big surprise, but they are missing something, which is the way that assumption looks like once brought into mind. Just as Steven Lehar depicted, in his words: "Beyond the farthest things that you can perceive in all directions, so, above and beyond the walls, floor, and ceiling of this room, beyond that is the inner surface of your true physical skull, and beyond that skull is an unimaginable external world of which all that you see here is a miniature internal replica."

I find this visualization a little disturbing but at the same time quite fascinating because it perfectly illustrates what we are dealing with. This visualization implies that the thing we believed was inside our heads, the brain, is not there, instead, what we consider as our heads is actually a miniature replica, which is hollow like the virtual head of a video game avatar, where the superficial appearance is only necessary to render.

This copy simulates the true physical head whose inner surface resides beyond the walls of what we experience. The bluish dome of the sky that we tend to contemplate at any time during the day can be conceived as a recurrent configuration of our world simulation's ceiling sheet. Above that dome we can find some neurons and glia, alongside the inner surface of the true physical skull.

It is worth mentioning that this illustration seeks to represent the essence of indirect perception relative to phenomenology and its theoretical location, leading to a more accurate depiction of the overall premise that we've been discussing previously. As it has been explicitly stated, indirect realism assumes that our experience of the world and the internal representation rendered by the brain, are indeed the same entity.

But there's something in this premise that doesn't seem to fit. According to modern science, the compelling experience of the world we have, especially the visual part, is correlated with complex patterns of electro-chemical activity across the brain's cortex, but if we look into the brain of someone we won't find any subjective experience in there, as we would expect, we wouldn't find any qualia, all that there is are intricated and irregular morphologies of neurons flickering constantly, nonetheless, our visual experience appears as a seamless volume around us, that also include other low features embedded in it, such as colors, mirroring effects, shadows, and light intensity.

Furthermore, how can we tell the difference between auditory qualia and visual qualia in the brain, if both come in the shape of neurons firing up almost randomly? If neurons are involved in rendering visual experience, why don't we even see their shapes appearing from time to time in our visual field, almost in a phantasmagoric way, floating in the "air" or covering the surfaces of objects, and the faces of our love-ones?

Wouldn't be fun to see intangible neurons floating around and appearing in random surfaces?
This drawing depicts the essence of the previous premise.

After all, the space we sense around us, the objects that appear solid and stable, the people we know, and the sky over our heads, turn out to be a set of sophisticated parameters and metrics that the brain uses to represent what's happening in the remote external world.

This problem is known in philosophy and neuroscience as the hard problem of consciousness. The world of experience has to be somehow contained inside the brain, it's almost undeniable, just as was exposed with previous arguments based upon evidence, though we don't know how it fits in there. However, this visualization helps us to notice the gist of the indirect realism argument and even though there's not a definitive solution to the hard problem yet, there's a concept that helps us to overcome that gap and keep studying consciousness.

This concept receives the name of "Qualia formalism", which assumes that for each moment of conscious experience, there's an isomorphic structure associated with it, that also can be mathematically described, and even modeled. So, any feature that could be identified in any moment of experience has to be correlated with a certain type of configuration within the structure associated with such phenomenology.

The world simulation we inhabit has to be correlated with a dynamic structure sustained by the mechanisms of the nervous system, which in theory could be mapped through rigorous methods. Therefore, even though we don't have a clue yet about the thing that allows conscious experiences to be the way they are, we can argue that our world simulation has two equally correct interpretations, whether it is a full-rendered volumetric model as it explicitly appears in experience or patterns of electromagnetic radiation shaped by the neuron's arrangement and morphology.

So, within this picture, both illusory alternatives are somehow the very same thing, without the need to consider any sort of dualism, because mind and matter end up being sides of the same coin. Then, we can argue that the visualization is right by depicting visual experience as an isolated space inside the brain, that includes all the properties observed in phenomenology, emphasizing the role that it has, as a representation of the remote external world beyond the biological layers that cover it up.

This visualization also suggests that visual experience is rendered in the brain in a shape that resembles what can be associated with a diorama. This is something that Steven Lehar noticed first when he was studying the properties of visual phenomenology. We can think of visual experience as a volumetric model that includes perspective since it is based on two-dimensional information, which is an adequate way to represent an infinite space in a finite representation. Although the brain takes advantage of perspective to represent distance as a function of size, it also uses a spatial scale to render the scene.

Another illustration made by Steven Lehar depicts the way our visual experience is rendered by the brain. The space inside the representation is warped because it blends continuously as it represents distance until collapsing into a plane.

Relative to the observer —"the homunculus"—, the things that are closer to it are rendered as large and compelling volumes, while those far enough appear as miniature models embellished with slight depth, then, the farthest things in the scene, such as distant mountains and clouds, collapse into flat images as if they were painted on the dome of the sky.

The phenomenon of perception is quite demanding, in the sense that the brain has to deal with a lot of missing information due to the limited capacity of the senses, hence, the way we experience the world might not be a flawless and accurate recreation of the genuine external world, but instead, a representation good enough to meet the requirements to effectively ensure the survival of all the organic tissue and machinery that covers it up, and thus, keep replicating.

Bear in mind that our brains are machines that follow the laws of Darwin, better known as natural selection, therefore, the representation that we inhabit and naively call reality is also attached to the slow process of evolution. After all, through the lens of indirect realism, our conscious experience of the world is seen as some sort of sophisticated interface with an adaptive design. As with any interface, our world simulation provides a bridge between sensory information and motor functions.

Therefore, as you might have already inferred, the qualia that furnish our conscious experience do not directly correspond with aspects of the physical world that modern science describes, instead, qualia are correlated with certain patterns of brain activity, which also suggests the existence of parameters that dictate those values of qualia. We can think of our experience of the world as some sort of balanced set of "organizing principles" that are set to generate the right atmospheric changes inside our world simulation.

For example, the colors that we experience can be thought of as a feature of the representation we inhabit that was implemented by evolution to simulate nuances in electromagnetic radiation. This is the idea of selective qualia, which consider the qualitative properties of conscious experience as not mere accidents, but instead as advantageous "widgets" that our brain uses to represent certain aspects of the external world. This is true for every kind of qualia that you could find inside your experience as well, such as sounds, scents, textures, and bodily sensations.

As I previously mentioned, there's a certain amount of underlying parameters that are responsible for maintaining a complete and coherent representation of the remote environment, so we can experience a solid and stable world as we commonly do.

We can think of our world simulation as analogous to a theater play, a super-immersive and sophisticated one, where there are a lot of mechanisms and advanced technology hidden behind the stage that generate the expected effects within the play, according to whatever's written in the script might be, so it allows the play to keep evolving. In this analogy, our surroundings are the equivalent of the scenery set on the stage, which is always being changed as the play continues.

Well, at this point I'd argue that theater is one of the ancient ways of depicting human experience, which has been perfected until our modern days, in the form of movies and especially video games. The theater has been evolving to make plays always more immersing, and that's exactly what we're going to achieve in the future when virtual reality technology reaches its maximum potential, so it will be indistinguishable from actual experience.

I think it represents the tireless quest of humanity to take control over the "fabric of reality", which is nothing more than the human brain itself. As I explicitly argued, the brain is not inside of us, we are inside the brain, and we're creations of it. Being human is a story that the brain tells itself, it's an interface to interact with a remote environment. We experience the world and interact with it, indirectly.

As I tried to depict with the last analogy, we inhabit what could be defined as a "simulator" or "matrix" that's finely adapted to render stuff. I'd think of it as the first and most advanced "3D modeling software" that has been ever created. After all, it's the fabric of reality of what we're talking about.

This matrix is made up of parameters that can interlock with each other to generate the appropriate effects or features that contribute to the creation of a complete representation of the remote environment that lies beyond the grasp of our brains. In other terms, these parameters are constantly morphing to couple with the sensory input the brain receives, generating in the process a congruent depiction of what's going on in the external world.

The solid and stable world we experience around us can be seen as the balance between interlaced forces inside the simulator that the brain instantiates. Whether when something distorts the feedback between the simulator and the sense data, or directly interferes with the parameters that are responsible for rendering the world around us, such as what happens with drugs, it gives rise to what we can experience as perceptual disturbances.

After all, we only have access to a representation rendered by our brains, hence the flaws of that representation are at the same time the flaws of our perception. Ergo, perceptual distortions can be seen as glitches that occur when there's some sort of interference that prevents our world simulation from getting correctly modeled or rendered. Phenomena such as altered states of consciousness, hallucinations, and dreams are explained easily by this same premise, we can think of them as abnormal but predictable behavior of our world simulation.

The experience of being a human resembles a bizarre cartoon...