Prisoners of our own receptors

"Cogito ergo sum." I think, therefore I am. This is how the French philosopher Rene Decartes, long ago, put the starting clue for a long branch of philosophy called epistemology, which tries to understand how is it that we know what we know and how do we justify what we assert. We all have this percept of being "in charge"; of knowing what we are, what the world around us is made of and what happened yesterday or is expected to happen tomorrow. But, is this even remotely true?

Prisoners of our vision

Credit: Pxfuel.

Anyone who has taken high school –or even middle school- physics will know that light is but a thin strip of the electromagnetic spectrum. X-ray, radio waves, microwaves and gamma rays are all but because it's what we can perceive, but it really holds no special qualities. If the survival of mammals was optimized by X-rays, then that would be what we perceive, and it would be virtually impossible for us to understand what it is even like to perceive the wavelength of 500 nm. But our cones can only perceive those wavelengths that maximize our survival; the wavelengths offering us the most optimum view of the world. If monkeys didn't perceive the bouncing wavelengths from lions and other predators, they wouldn't survive to reproduce. We called it light.

But then, how did we find out about X-ray and ultrasonic waves and the nano-sized DNA molecules if we can’t perceive them directly using our sensations? The answer is simple; by using transduction machines. Machines that convert a non-visible stimulus to a visual one. This is due to the fact that we are mostly ‘visual’ animals. If we were ‘olfactory’ animals like dogs and rats, we would probably want to transduce all stimuli to olfactory ones! We only know of the X-rays because of the visible effect they have on a bleaching photographic paper; we only know of ultrasonic waves because they can be detected and displayed electronically to view as a visual signal; we only know of the DNA molecule because of the various reactions we can make it undergo to cause visible (or visibly detectable) changes in the lab. So does this solve the receptor bias problem? To some people, it does, but I highly doubt such assertions. I think it is not only highly probable, but almost inevitable that there are stimuli which are too difficult to transduce, or cannot be transduced into something we may detect with our current receptors.

A couple of years ago, I read a classic article called "What is it like to be a bat" by Thomas Nagel. In it, he starts to wonder what would it be like if one of us humans became a bat the next day? What would it "feel" like? You can argue, one way or the other, that you would literally "see" in ultrasound! The reflected waves would be perceived like colors to you, and you would literally feel in charge of the world with your limited ultrasound detection machine. But does it mean anything to even ask that question? If you became a bat, would you even be able to still hold the human view of the world, or is it a necessity for one perception method to wipe the other? And, are bats actually conscious of what they perceive in the same way that we are? I'll let you think about this for a while, and I'll leave you with the actual article to dwell on.

Ishihara color blindness test.
Credit: Wikimedia Commons.

Well, if you can't perceive what a bat is perceiving, then you can surely perceive what fellow humans are perceiving, right? Unfortunately, this is not the case. Remember that the sensitivity of your cones depend on certain things as the exact wavelength at which the 11-cis retinal gets converted to all-trans retinal and the distribution of activation along the retinal surface. Also, what about the downstream signaling? Is it exactly the same in all individuals? Don't we all have pleomorphisms and variation in the opsin molecule, rendering the exact response to the same wavelength different between us? Don't we have synapse structures that are  different in detail (albeit similar in "broad" effect? Or, to take it to the extreme, don't some of us suffer from color blindness,  having a different perception of the world, and a range of wavelengths they simply make up using the firing ratio of the two remaining cones they have? Those people may not know they perceive the world differently until confronted with an objective test that examines their accurate differentiation of colors.

This idea, as scientific as it might seem, is very easy to deduce from a philosophical standpoint as well. For example, imagine there's a irregular object being looked at by three different people. Each one of those people will be seeing a different angle of the same object and perceiving what they see as the ultimate reality. They can argue for ages about the shape of the object not knowing that the root of their disagreement is the sole difference in their angle of view. Or, the exact opposite may be true; they may reach the conclusion that their descriptions of the object complement each other and reach the conclusion that a single object exists, when in reality there is many objects, and they only seem to be part of the same thing.

Prisoners of our inner version of reality

This analogy, simple as it is, can be extended to the deepest issue of all; the existence of objective reality. Does an objective, independent reality really exist? Judging by the fact that our percepts of the external world seem to be complementary, and seem to be matching in description, this is a plausible argument. YET, you can never be sure. There's always this tiny margin of uncertainty that we might really be describing different realities. Let me ask you this question: how do you know that you exist? What if the movie matrix were true and you brain was really being manipulated by aliens to perceive the existence of a body? Or maybe you're just in a big dream, an illusion. "I think therefore I exist" is the closest we can get to a "certain" answer.

You might think this is pure philosophical bluff said by eccentric individuals who just like to complicate things. But have you considered re-visiting "self-evident" ideas before? For example, the idea that your body belongs to you and not to someone else might seem so self-evident that you would say it is ridiculous to even question it. But what if I told you that this is a mere percept synthesized by the brain to protect the big clone of cells having identical DNA from harm; after all DNA is the most important asset in an environment of biological evolution. Ever heard of a syndrome called contralateral neglect? In this syndrome, damage to certain areas of the brain leads to the loss of percept of half of your body, to the extent that you would wear half your pants, put lipstick on half of your lips and treat the contralateral half as belonging to a stranger!

Prisoners of our senses

Vision is, sure enough, not the only system in our body where uncertainty is the rule. Pretty much any sensory modality has to suffer alteration. Think of receptor potential. The receptor response to stimuli isn't always linear; most of the time it follows the exponential rule with small stimuli and the log rule with large stimuli. What this means, in essence, is that you do not perceive the world as it really is! If I double the pressure on your palm, your receptor makes you perceive it as if I only increased the pressure a little. But why would it do that? Again, evolution. The function of the receptor is to perceive as wide a range of stimuli as is possible to maximize survival. The receptor doesn't "care" whether you perceive reality as it is. It only cares that you perceive it in the way that maximizes your survival span to reproduce and propagate your genes.

So let's jump to another sensory modality. Do you know that human beings have 1000+ olfaction genes out of which only ~300 are active? While this is not the place to discuss pseudo-genes and their relationship to evolution (as much as I'd like to), this tells you something about the limited scope of our perception of olfaction. This is a well-known fact, yet seldom dwelled upon in depth. If all our olfaction genes were active we would be as good as rats in detecting scents and pheromones.  Even then, it's a shame to say that we would still not be able to detect all the organic molecules in the air. You can only perceive those molecules that have the property of being able to dissolve in water, with slight lipid solubility in order to be able to dissolve across the thin watery mucus layer covering your olfactory epithelium. That is, only those molecules that manage to get to your receptors are going to be perceived.

This should lead us to one of the most bizarre and intellectually fascinating ideas. We all think of sweet food as being good and bad smells as being repelling. We all think of lust as being enjoyable. We all enjoy beautiful objects, music and social relations. But did you ever consider that in reality, things work the other way around? Fruits are sweet BECAUSE our body needs them, so evolves this percept of reward whenever they're eaten. Lust is good BECAUSE it rewards the activities that maximize our genes in the gene pool. Even pain is an evolved percept to make us move away from harmful stimuli. After all, who could actually imagine that the excruciating pain experienced when burned with fire is the mere firing of receptors in response to infrared radiation and released electrolytes from the damaged cells? Our percept of beauty ITSELF is related to our survival, as you might be surprised to see in this fascinating talk by Dr. Ramachandran.

The concept of our imprisonment within our own receptors and perception was tackled so far from a perspective meant to show our faulty perception of the outside world. But let's do this inside-out. Don't you find it bizarre that the organ you are most aware of is the skin, when there so many more important organs such as the liver, the heart and the brain?! Simply, the scarcity of receptors in these organs makes them less accessible to our awareness than skin. Ironically, the most important organs in your body are the ones least needy to reach your perception. On a different note, you can get totally synthesized percepts of organs that do not exist simply because their receptors still exist, and the phenomenon of phantom limb is the most striking example.

Prisoners of experimental and physical uncertainty

The concept of uncertainty is as old as experimental science itself. When you take any measurement, there are all sorts of factors that can cause your value to be mistaken. Some are related to mistakes in the procedure, others related to the measuring instruments that you use, and others related to the environment and background during which the experiment was taken. Early experimental physicists did notice this issue, as hence the invention of margins of uncertainty. Using various methods and tools, it is possible to give a "plus-minus" beside every measurement you take, making sure that you do your best in accounting for variables and random errors.

Heisenberg's uncertainty principle.
(Click link for description)
Credit: Wikimedia Commons.

As the twentieth century unfolded, the word "uncertainty" was pinned with an even deeper meaning. This is because the famous Heisenberg's uncertainty principle was proposed. According to this principle, which is one of the hallmarks of quantum mechanics, you can never measure the position and velocity of a subatomic particle simultaneously. To make this easier to grasp, think of electron microscopes, how do they work? They send electron beams which as they strike the surface in question, they bounce off in various directions that can be interpreted by the computer to reconstruct the object. So, it's either you measure the initial position of the subatomic particle and not its velocity (since the electron itself that hit it caused it to wiggle and change velocity), or you measure the velocity of the particle by sending two successive beams to measure its change in position but not its initial position (because it's been knocked off by the electron). At least that's my lay interpretation.

You might want to think of this principle as a simple fact of measuring limitation, but in reality it’s also a concept of what really is out there. The position of a subatomic particle is never certain, and this might lead to things as counter-intuitive as appearance of subatomic particles out of nothing and their quick annihilation. I'm fooling you not, this has some experimental data to support it! To be honest, this whole concept is never easy for me, a non-physicist, to understand, but, you might wanna try this for a starter.

Prisoners of our inner confabulations

So far, we have been talking about uncertainty in terms of physical quantities and experimental data. Now I would like to add another element of uncertainty; that is, observer bias. And by that I do not mean intended bias or error in taking measurements. I mean unconscious bias; the bias of perception and memories.

You see, the way the brain works is not like a recording tape where it takes the events as they are. If it did, it would be no better than the tape, wouldn't it? Your brain takes in the best image of the world that suits your survival. It is actively interpreting and re-interpreting events and evaluating them to various degrees. It fills in the gaps, justifies inconsistencies in the image and supplies you with the most plausible percept it could generate based on its design and previous experience. For a straightforward starter, remember one day when you and your friends were hanging out together and telling horror stories to each other. Somehow, everything looks scary, and if a cat just passes you might jump in shock thinking the Boogeyman has come. Because you expected the Boogeyman to come, you perceive what comes as the Boogeyman. This, as well as more accurate experiments, has led to conclusion that the brain's expectations, emotions and current state of mind can alter the perception of the world. If you're happy, you look at every percept with optimism, if you're sad you paint gloom on every percept and if you're angry you might have a "perception-block" and not be able to perceive things at all. As subtle as this may seem, this alteration of how you perceive events could result in remarkable difference in how each of us perceives them.

Your brain would never hesitate to synthesize gap-fillers if they were to complete your perception of the world (albeit unrealistically) to maximize the propagation of your genes.  As we all know, there's an area of the retina which lacks photoreceptors called the optic disk, where the nerve axons exist to reach the brain. But how come there isn't a hole in your vision? Another striking example of false continuity is the fact that you see people and objects as being "solid" and "continuous". What I mean by that is, everything is made of atoms and molecules, right? So why don't our senses see that? And the answer might be that we do not need to, or that there hasn't been enough time and evolutionary selective pressure. For similar reasons, our brains have coped to deal with objects occupying physical space. This is why we find it very counter-intuitive to imagine waves, where the concept of space-occupation has totally different meaning. Just try to imagine what I mean by "light is a wave" and I assure you, you will have to convert its image into a particle-like model in order for you to imagine it.

Even our perception of time is adapted to deal solely with those timescales that affect our survival. You never realize your hair is growing continuously despite the fact that it really does, simply because the rate at which it does so is too slow to have an effect on your survival. In fact, this is really fun to imagine. I mean, what could possibly be more fascinating than the fact that every atom in your body changes every several years, yet "you", as a totality, are the same?

Moreover, there is the concept of attention. Attention acts as the "bottleneck" through which some information is passed and analysed in greater detail than others. For example, while reading a book, the entire surface of the book falls into your retina and gets send into your brain in the form of axonal signals, but only the word you are focusing on a the moment gets analysed in great detail. In fact, a fly might be standing on the tip of the page and you wouldn't notice it despite its image falling into your retina, simply because your brain's attention is drawn towards what you are reading.

Prisoners of our collective confabulations

This leads us to another form of uncertainty; the uncertainty of historical accounts. I've been dragged into a discussion with a few friends of mine about the validity of historical accounts which were based for a substantial period of time on face-to-face propagation. My friends claimed that as long as we could trust the person saying it, in terms of honesty and competence, then we can be "100%" sure that we received the correct data. But, let's think of this in light of the previous argument. There are three "levels" of faulty face-to-face transmission:

• Mis-perception – the person could've heard in correctly, had their emotions interfere with what's being heard, or their memories alter how they perceived what they heard.
• Mis-remembering – the person might not recall the knowledge correctly, or remember it with an emotional "twist" depending on the person's mood at the time of perception and retrieval.
• Mis-communication – the person might not be able to communicate what they perceived correctly to the other person, because of a language barrier, inadequate explanation or simply because the receiving person misunderstood what the first person said.

Add these three levels of mistake and multiply them by the number of people along the vertical line of transmission and you start to get an idea why uncertainty in historical accounts is inevitable, no matter how trusted the people presenting them are. A similar argument can even be made for written accounts, but of course, they would be less prone to error.

Are we really "prisoners"?

As negative and cynical as this piece might seem to be, it actually carries a very positive message. Knowing that reality is beyond our perception is, if anything, a humbling experience. It puts things into perspective and should make us worry less about trivialities. We are 100% capable of deeply enjoying something that we know is not an accurate representation of reality. After all, don't we enjoy movies, despite knowing that actors are just playing their part? Don't we enjoy art? Visual illusions? "Magicians"? Our inner story is what matters to us, and that is OK. By the same token, we can still act as though we are truly in charge and have free will, all while acknowledging the fact that we don't, but that's a whole different discussion.

Peace :)

P.S.  The name of this account is inspired from my discussions with Dr. Hany Gamal, Professor of Physiology at Cairo University School of Medicine and a true inspiration.