Why did I save the sense of touch for last? I gave the matter a great deal of thought and decided that understanding the perception of touch to its fullest extent required the knowledge of the other senses. When Aristotle was exploring the five senses in his treatise called On The Soul, touch was the sense that he found most mysterious. To explain vision, he could point to the eyes. For hearing, he could point to the ears. For smell, he could point to the nose. For taste, he could point to the tongue. For touch, he couldn’t point to any one sensory channel. The skin? The body? The soul? What was the origin of touch sensations? To think another way, the other four senses were in fact part of touch. Light ‘touched’ the eyes which allowed us to see. The pressure waves of air molecules ‘touched’ the ear drums which allowed us to hear. The chemicals from food ‘touched’ the nose and the tongue which allowed us to smell and taste. Different dimensions of physical phenomena ‘touched’ the designated organ that was evolved to perceive it. Without some sort of contact between two things, perception was impossible. In other words, touch was the primary sense of all living things on the planet. In order to live, the boundary between the order of living systems and the chaos of the outside environment must pick up data from both ends to maintain equilibrium. That data was the origin of touch. Perception was required to seek out nutrients in the environment and the most primitive perception to find food was through touch. From this definition, one could infer that even bacteria had the ability to sense its immediate environment and the neighbouring cells. They possessed a primitive perception of touch between the cell walls. Perceiving from a distance (namely vision and hearing) was evolved hundreds of millions years later. The early life forms which were endowed with a distant sense were more capable of surviving and reproducing. It warned them of incoming danger and highlighted nutritious objects in the environment without risking direct physical danger. The distant senses were built on the system of touch. Evolution did not invent new features from scratch. It built upon existing systems which then became more adaptive to the present environment.

The physical nature of touch is more fascinating. The universe is almost completely empty space. The stars, the planets and living things are all part of normal matter which consists of 5% of the universe. The other 95% from dark matter and dark energy are unaccounted for. Not only that, the atoms of normal matter are nearly empty space. It is mind-blowing. The relative subatomic distance between the electron clouds and the nucleus is huge. If the nucleus is the size of a marble, the atomic size is that of a football pitch. The nucleus is where most of the matter is located which gives the atom its mass. But it is untouchable by conventional means because the electromagnetic attraction between the nucleus and the electrons creates a protective barrier. When you are touching something, you are not really touching its matter. You are touching the interaction between the electron clouds in empty space. It is a dynamic change occurring between the atoms of an external object and the skin. To put it more technically, the sense of touch detects the interaction of the fundamental force of electromagnetism. There are four fundamental forces of nature: gravity, electromagnetism, weak nuclear force and strong nuclear force. For creatures like us who live in the macroscopic world, electromagnetism and gravity are the most consequential. The other senses are extensions of touch because they detect other characteristics of electromagnetism such as the eyes detecting electromagnetic waves. Smell and taste experience the forces generated at the boundaries of intermolecular and chemical interactions. Other forms of life can detect magnetic fields like in migrating birds or electric fields like in electric eels all of which are instances of electromagnetism. These sensory data are translated into electrical signals in the nerves. The brain is a giant neural web of electricity. This is why the sense of touch is universal because life and consciousness exist at the level of electromagnetic forces.

In the case of humans, the touch sensations exist at the boundary between the body and the outside world. We can’t pinpoint it. It encompasses the entire being. Touch is not just one sense but many. It confirms our existence in the world. You touch the world while the world touches you back. This is why the feeling of touch feels magical. The deprivation of this foundational sense is a cruel punishment. Everyone knows that the fundamental needs of a human being are food, water and air. Without these things for a short time death will result. There is one more need that we have ignored because it works so well already in the adult body. Without the confirmation touch by another human, the body initiates a sequence of biological feedback loops that lead to self-destruction.

We see this fundamental need clearly in human infants. If you feed an infant, give it clothing and a nice shelter but refuse to touch the infant, it will die. The stress system goes into overdrive and the tiny body loses control of its functions. It is even worse for premature infants who are born too early. Without a loving adult touching them to confirm their existence, their body maps in the brain cannot develop. As horrible as it sounds, the circumstances that lead to this sorry state occur in rare periods of famine and war when infants are abandoned or orphaned. But babies are not as defenceless as they might seem. They have evolved cute characteristics in order to attract any bystander to attend to them even if they are not the parents. You have to be a monster to ignore a cute baby crying in front of you. As discussed in the visual pleasure model, cuteness prepares the brain for touching and parental instinct to activate. Even older children are wired to pick up a baby so they can get some parenting practice. The kangaroo care which fosters skin to skin touch between mother and child appears to be the most beneficial for both parties. Babies who receive plenty of kisses and loving touch from their parents are able to regulate stress better and gain a healthy amount of weight.

Kangaroo Care - The mother holds the baby close to her chest.

Even for an adult, the deprivation of loving touch is deadly. The tragedy of chronic loneliness is not only damaging to the mind but also the body and the immune system. A lonely person is more likely to develop chronic pain, mental and stress related illnesses. They are starving for a loving hug to give meaning in life. Without early interventions, suicide is not uncommon. Maybe that’s why people enjoy gathering and praying together so they could embrace each other. The deprivation of touch is a symptom of a larger problem in society which places a bigger value on fame and individual success rather than love and connection. The pursuit of fame leads to loneliness. Fame creates a social barrier around a celebrity so everyone is too intimidated to touch her and yet feel enormous pleasure when being touched by her also. It is usually the person of high status who initiates the touch. They give permission to be touched by the lower class. If a homeless touches a higher status individual without permission, he is met with scorn and punishment.

In societies with strong kinship ties like in Southern Europe, Latin America, South East Asia, they are less strict with casual touching between friends and even strangers. They also tend to be religious. Religious rituals help the people feel comfortable to hug their fellow brothers and sisters who belong in the same community. When I travel to these countries, I am fascinated to observe the male friendship rituals. In every culture, women are more likely to comfort each other because they are naturally more talkative and social. Of course there are always exceptional cases who don’t like being touched. But the men show the greatest diversity among cultures because the masculinity values vary a lot. In kinship-oriented cultures, male friends seem to be closer than the friends I know in Western Europe. In some places in India, they hold hands in public which should not be confused with romantic connotation. Not just between friends. Father and son hold hands. Uncle and nephew hold hands. Male cousins hold hands. Male intimacy expressed through touch is rare in the world. In contrast, western norms of male touching beyond a casual hug or handshake assume romantic relationships. Unless it is a unique circumstance like in a sports celebration in which case, almost any touch is permissible. There is a strong sense of shame for tough men to comfort each other which otherwise comes naturally to womankind. It is because they don’t want to expose their vulnerability. We will explore the intricacies of social touch in part 3.

The touch perception also has motivational qualities along with pleasure and pain. The body is constantly updating whether the environment is dangerous or safe. Some qualities are more dangerous than others. Sharp, rough, heavy and hot are dangerous whereas smooth, round, light and warm qualities are more comforting. This is universal for all mammals and birds. Humans go one step further. We use these qualities to judge the context of an environment. The atmosphere so to speak. This has enormous consequences for architects, interior designers, urban designers, chefs, lawyers, diplomats and many more. Here is a situation you don’t want to be in. Let’s imagine you are in a serious business negotiation with a lot of capital on the line. You are having a feeling that the person on the other side of the table is being a hard-ass and hot-headed even. He doesn’t seem to see reason. The negotiation is failing and you can’t pinpoint where it is coming from. You are feeling anxious. Then the other person accuses you of being a hard-ass and hot-headed. What? You thought you are the reasonable one. What is going on? The real reason you two are feeling this way is because you are both sitting on a hard-wooden chair in a hot room because some idiot forgot to lower the thermostat. Your body is feeling the hardness and hotness and then misattribute these tactile feelings to the other person. This is a disaster. In the next appointment where the chair is softer and the room is at a comfortable temperature, you both perceive each other as more reasonable and work together to reach a deal which every stakeholder is happy with. What is happening in the brain that it is recycling the touch processing areas to create moral judgments?

Neuronal recycling is a big part of why humans can perform extraordinary feats using a hundred thousand years old hominid brain. For example, when we learn how to read the brain recycles the visual areas for face recognition in order to recognize the letters. Then it couples the letters with their corresponding sound by recycling the auditory areas and Broca’s area. Finally, the sound is connected to its context and meaning by recycling the narrative processing areas in the prefrontal lobe. These discrete steps are performed rapidly to the point where reading feels quick and natural. However, reading should be taught after being fully immersed into the sounds of the language, not before. Otherwise the coupling process between letters and sounds will not be perfect. This is a common mistake with first generation of immigrants when learning a new language. They learn to read and write first without being immersed in speaking and listening. Their language proficiency can never match a local speaker. In the same way, the brain recycles moral judgments from touch processing areas. We use touch metaphors to describe personality or moral qualities such as when someone is hot-headed, tough, soft, a smooth talker or has a sharp mind etc. These are not just metaphors. The brain literally recalls the tactile sensations in the somatosensory cortex, the visual cortex along with the limbic system when describing someone. Similar to reading, they are performed in discrete steps within the network. Yet it feels natural and rapid on the conscious level. This is a remarkable feat because touch is the primary sense we use to feel the world and it is also recycled to feel the social and moral interactions as well.

It is important that the tactile sensations of the immediate environment do not cause contradictions in the moral judgments of a person. It is easy to misattribute what the body is currently feeling to the personality in front of you because they are processed in the same brain areas. When you are negatively judging a person, first be aware of where you are sitting, the temperature you are feeling, your posture and the level of bodily comfort. If the environment is not the issue, then your judgments will be more accurate. On the other hand, you can manipulate the environment to your advantage to create a specific mood for the occasion. For example, if you want to create a romantic mood for your partner, the best way is to transform the tactile feelings of the room by making it softer, smoother, rounder and warmer. It is hard to feel romantic in a cold messy room.

Exteroception

Different-types-of-mechanoreceptors-and-their-details-Purves-et-al-2008.jpg

What does the touch system do? The short answer is everything else the other senses don’t detect. As I have stated, they are just extensions of touch and tend to specialise in one aspect of electromagnetic force. The feeling of touch on the skin detects multiple aspects of electromagnetic force simultaneously. Well it is more complicated than that. There are specific nerve systems for mechanical touch, temperature touch, itchy touch and social touch. You might be aware of erogenous zones of free nerve endings which determine the areas for erotic and tickling touch. They remain separate throughout the nervous system. However, the nerves are not spread evenly. There are hotspots on hairless skin (like the palm of your hand) for discriminative touch or hairy skin (like the forearm) for caress touch. For now, let’s focus on the discriminative mechanical touch. In the somatosensory cortex, there are touch maps that activate in response to different areas on the body. The hand and the fingers have asymmetrical distribution of mechanoreceptors and hence a bigger real estate on the touch map. The same is true for the lips and the tongue compare to the rest of the body. There are four types of mechanoreceptors. Merkel Disks are sensitive to consistent skin deformation which allows us to sense the boundaries of an object. Meissner’s Corpuscles are activated by low frequency vibration within a local area which allows us to the grip the object at exactly the right force to keep it in place. Pacinian Corpuscles which have been introduced in the Kinaesthetic Pleasure Model are activated by high frequency vibration anywhere in the finger which allows us to feel an object as an extension of our body. Ruffian Endings are sensitive to horizontal skin stretching which allows us to detect the speed of an object on the skin as well as preparing for finger movement. When you feel a spider crawling on your skin, it is thanks to the Ruffian Endings. These nerves contribute to our tool use and other peculiar abilities like reading Braille. The separation of each nerve to its mechanical sensation is an academic exercise. They never work alone. It is the data from all the surrounding touch nerves that are sent to the touch maps in the brain for processing.

Here is a more fun question to ask. How do we feel something sharp or dull? Smooth or Rough? Wet or Dry? Soft or Hard? Heavy or Light? Which nerves produce these sensations? All of the nerves and more. We can mathematically measure how heavy something is by using weight scales. We can objectively measure how sharp something is by how much pressure it is causing over a given area. We can measure how hard something is by pulling it apart. But to subjectively feel these qualities is an emergent property of the brain. There are no specialised nerves for sharpness, hardness or wetness. All of the touch nerves, the skin, the muscles, the bones, and the entire body are involved in sensing the intrinsic physical qualities of an object by how much this object has changed our body in a split second. In other words, the body is the ultimate deformation sensing tool.

The body is a system that seeks to be deformed by the world in order to sense the world. It is pleasurable to do this since the body needs to extract useful information from the environment to assess danger and seek out nutrients. The touch information is combined with vision, hearing, movement, balance and proprioception to create a rich blend of touch images. When you were a child, you might come across a strange toy that you have never seen before. Looking at the toy was not enough. You picked it up and tried to feel how the parts fit together. Your fingers were actively investigating the surfaces and connections of the toy. You might twist some parts to see whether they were hard or soft. You might tap it to hear whether it was hollow inside. You might even bite it to see whether your jaws were strong enough to break it. If you were a wild child, you might try to drop it multiple times and tried as hard as you can to break it apart. If you were a pyromaniac child, you might try to burn it with fire. What this demonstrates is that the touch sense is not passive. It requires the movement of every relevant part of the body to investigate what a foreign object is and figure out its affordance. Affordance is the purpose of an object. Only by doing an active investigation that you figure out what an object is used for. It takes some time for a young child to figure out that a cup is used only for drinking, not for playing an aeroplane. If you are really clever, you might do a theory of mind prediction to use the object as the designer intended. You are reading the designer’s mind. Active touch investigation is a deep instinct possessed by all primates. Primates including us are naturally inquisitive of the world and use their limbs to explore the objects in an environment.

This is why a no-touch policy in museums is so unnatural. Vision is not enough to understand the full dimensions of an object. You need to touch it to verify what the eyes are seeing. Vision is plagued with optical illusions and yet everything is locked away in glass boxes. The policy started in the 1800s and it took a hundred years of cultural enforcement to discourage the public from touching valuable historical and artistic objects with their dirty greasy uneducated hands. There is also the worry of theft. I understand the problem about the greasy hands but in the 21st Century it can be easily solved by providing everyone with hand wipes. The issue is more of a class discrimination. For example, the British Museum hold 8 million artefacts in its back storage which can only be accessed by elitist curators. Surely the museum can spare a few objects from reserve collections to be explored by the public. Reserve collections are copies of an original object so it’s not a big deal if they break. Active touch investigation is learning by doing which is more fun than learning by seeing alone. By touching an intricate object like an astrolabe, we might figure out what an Arabian astronomer of the Middle Ages was thinking when he/she was measuring the celestial spheres, finding the direction to Mecca or keeping track of time. At the same time, we are also feeling the designer’s essence through touch and across time. For some, this is a profound spiritual emotion. History becomes more fun to learn with the pleasure of touch. The affordance knowledge is more important than looking at pretty objects in glass boxes. What is the point of saving these artefacts for the future generation? Who are the future generations? Will they care about history instead of the latest version of the matrix virtual reality gaming machine?

Speaking of virtual reality, our instinct for active touch investigation do not disappear in the virtual world. It is heightened instead due to lack of tangible consequences. The players are motivated to test the physical properties of the game world, how far they can push it before the game systems break down. They are touching the objects in the game via the avatar’s actions and destroying said objects on purpose to see how they would behave. It is humorous to cause a bit of destruction. If the player creates too much mayhem to continue the game, he can reload a previous save to reset the world state. We do not get into trouble if we break things in the virtual dimension because they are infinitely reproducible. Every object in the game is just computer code. The developers can repeat it as many times as they desire. In fact, that is how they build the game world in layers. First, they build the geometry of a level layout that fits the theme of a scene. And then they place the in-game objects like chairs, tables, cups; or weapons such as swords or guns; or vehicles such as chariots, cars, boats, planes in layers. The game engine has a suite of physical properties such as lighting engine, sense of speed, breakability, collision detection, ragdoll physics and gravity to simulate how the objects will behave to the player’s actions. These attributes can be manipulated like changing gravity values to slow down or speed up falling. The more layers of physical properties they can add, the more real it feels to navigate in the level. The developers don’t need to create the exact laws of physics of real life. They use polishing effects such as trail effects, particle effects, physical interaction animations, sound effects and rumble vibration from the controller to trick the mind to believe that an object feels real.

Video games have exposed the close connection between the touch systems and visual and auditory systems. The touch perception is multisensory. All the senses work together. Since the active touch investigation is limited in the virtual environment, the developers compensate this by creating visual and sound effects that imply the tactile properties of an in-game object. However, it is very difficult to fool the brain. The smallest of glitches can break the immersion. By the time you are old enough to speak, the brain has already mapped most of the physical properties of the world. You instinctively understand how things behave because the laws of physics are consistent at least on the human level. In virtual environments, the laws of physics are coded by humans and prone to failure. The brain doesn’t tolerate these failures such as when the gravity is broken or things don’t collide as they should. They are targets of satire memes by the internet in order to express the incompetence of a game.

Let’s take a look at an example of simulating a large heavy object. Where do we start? When a light car and a heavy car collide, the light car receives most of the damage while the heavy car hardly moves. If you drop a heavy metal ball and a light rubber ball from a height, the heavy ball falls faster. An elephant moves slower than a rat. The elephant footsteps are louder and create small shockwaves on the ground. If you swing a sledgehammer, it can break any glass material compare to a balloon hammer. It takes more muscular effort to swing a sledgehammer than to swing a tennis racket. If you are hit by a heavy punch, it is more painful than if you are hit by a light punch. If you throw a big heavy stone into the water, it makes a bigger splash than a small stone. All of these are subjective observations. They are stored in the brain as tactile images from a lifetime of touch experience. These images are also multisensory as stated earlier. The game developers have to match the polishing effects with the tactile images in order to create a believable effect.

In Shadow of the Colossus, the protagonist has to take down 16 colossus monsters in order to save the girl he loves. Each colossus is hundreds of times bigger than him. The game revolves around seeking out these monsters in their natural habitat, climb their body until he finds a weak spot to stab the magical sword into it. Although the game world is vast, there are only 16 enemies. The protagonist has to travel far to get to each one. When he encounters one, the game has to sell the extraordinary nature of such an event. The fact that they are very big and terrifying. The first thing I notice is that the creatures are slow but each footstep leaves a small crater on the ground. The camera also shakes in accordance with the steps. Their general movements leave echoes of sound in the surrounding land. If a colossus is in water, it creates big splashes and bubbles around it when it swims. If a colossus is flying in the air, the game simulates swirling wind patterns around its body. Some colossus carries a giant weapon that are equal to its size. When it swings the weapon, it takes a few seconds of effort which give enough time for the protagonist to escape. If it does hit, it leaves giant visible marks on the landscape. In the remake version, the developers added new polish effects in the game world as well as the colossus themselves. My favourite is the fur effect. Every strand of fur moves independently to one another. When the protagonist climbs onto the fur, he leaves collision marks on them. The fur adds the feeling that these creatures are real and alive. However impressive the polish effects are, they are subservient to the narrative. The game is selling the perception of epic encounters with these giant creatures. It is imitating real life tactile perception but it also exaggerates them to add new storytelling mechanics. It is pleasurable to experience this because the mind is transported to a new world of wonders.

Interoception

As impressive as sensing the outside world is, it is not enough. It is not common knowledge but there is a parallel touch system that is evolved to sense the inner condition of the body itself. This is called Interoception. Our body is a whole universe of competing systems and microorganisms that we host as mutually beneficial allies. The feedback from these systems must be picked up by a different sort of touch receptors so the brain can figure out the current status of the body. When exteroception detects properties of an object, it is sensed by myelinated nerve fibres that are capable of transporting the signals quickly to the brain. These are nerve highways because knowing the physical condition of a dangerous environment requires a quick response. But they are also energetically expensive. The body cannot afford to use these nerves for all kinds of touch signals. For interoception, the body uses unmyelinated fibres that travel much slower. There are many advantages for slow transmission. Firstly, it doesn’t compete bandwidth with the nerve highways. Secondly, the slow signals are processed by the emotional centers of the brain. The inner homeostasis of the body is tied to emotion. Since humans are the most emotional and social creatures in the animal kingdom, our interoception is highly developed compared to other animals. It is one of the superpowers of the human race.

Similar to exteroception, interoception is not just one thing but multiple sensations emanating from different sources in the body. There is a sense of ownership attached to them. There are ergoreceptors that evaluate the condition of skin health, muscles, joints, teeth, bones etc. If anything goes wrong, you will have a weird feeling around the local area of the damage. It will be accompanied by slow pulses of pain. There are two kinds of pain, fast and slow. When you bump your elbow to a furniture, you feel the fast pain which is carried by myelinated nerve highways. You feel the fast pain with pinpoint accuracy of where you get hit which activates the reflex response. Then after a few seconds, you will feel a slow wave of dull pain around the area. Slow pain is carried by the unmyelinated receptors which means emotion is injected into the conscious awareness along with the pain. You will feel angry or annoyed that you moved in the wrong way for your elbow to get hurt like this. Even when you are moving about in your everyday life, you feel a state of contraction, tension, aching and burning sensations since the body is constantly deformed by its own actions. Different postures bring weight and tension around the areas of the body that are perpendicular to the earth’s gravity. It requires work and energy to stay upright. If you forcefully move your muscles at high intensity without a proper warm-up, they will cramp up and cause severe pain around the area. The body will not always listen to your commands because interoception is keeping you safe. This has huge consequences in competitive sports.

There are unmyelinated touch receptors for slow pain, itch, tickle and affective touch. These are distinct from mechanoreceptors like corpuscles. We will tackle the tickle and affective touch in part 3.

There is also a feeling of thirst that is mediated by the levels of water and fluid electrolytes in the blood. The concept of vampires is developed in literature because they have a supernatural form of thirst that is uncontrollable in the presence of human blood. Supernatural characters often have exaggerated abilities of human perception.

There are feelings of hunger and the need to urinate/defecate that are mediated by the gut and the brain stem working together. The gut has its own enteric nervous system to control the processes of digestion with incredible precision. If you eat something bad, it will generate uncomfortable feelings in the stomach from food poisoning. Every culture has superstitions on which foods should not be eaten together. Maybe someone in the past ate such a combination and succumbed to lethal food poisoning. The knowledge got passed down among the survivors and after many generations turned into superstitions. The gut is also involved in generating emotions such as the feeling of butterflies in your stomach when you feel in love. If you sense that you are being stalked by a creep, you will feel a sense of heaviness in your gut along with increases in anxiety. Just RUN!

There is a feeling of air hunger if the respiratory tract is blocked like in the case of choking or severe flu. Darth Vader uses the Force Choke on the enemies to establish his superiority. When you are walking in nature, you feel the freshness of the air and it feels pleasurable to breathe deeply. The sheer volume of outside air has a positive quality compared to indoor trapped air. On the other hand, if you are stuck in a room all day such as in long business meetings, you will suffocate and suffer from cognitive errors due to low oxygen levels in the room. You may want to open the windows to let some fresh air in.

The immune system can also generate interoception if you are allergic to something, if there is an infection, or if you have an autoimmune disease where the immune system attacks normal cells in the body. The inflammatory response is activated for self defense and healing purposes. It is generally painful and uncomfortable. One can argue that interoception is an immensely complex network of sensations that are keeping the body alive. Most of the time it is beneath consciousness since it works so well on its own. Yet if anything goes wrong, interoception assumes priority in the brain so you can attend to healing and relaxation. We will explore more about relaxation in part 2.

I cannot count how many times I have watched the Disney animated adaptation of Jungle Book. When I was young, I used to have a VCD of the movie which I carefully stored in a disc folder. Yes, a VCD. I feel old. Whenever I wanted to watch, I put the disk into the VCD player and let it play. I loved the concept of a human boy growing up with wolves, a panther and a bear. Back then, I couldn’t understand English so the words meant nothing to me. Because the animations of the characters were expressive and tactile, I understood the gist of what is going on. My favourite part of the movie was when the bear, Baloo taught the boy to enjoy the simple pleasures of life with a catchy song called Bare Necessities. I would sing it along every time although I didn’t understand the words. In the song, Baloo demonstrated the pleasure of eating and enjoying in nature. He did not need any expensive luxury. The pleasure of touch provided by nature was enough. The most prominent example was when he found a tree to scratch his back. And then stood next to a boulder to scratch it some more with a pleasurable look on his face. This was a reference to real bear behaviour. It was one of the pleasurable behaviours a bear enjoyed every day. I also saw cats and dogs scratched and licked themselves all the time. Even as a child, I understood what this meant. Scratching an itch felt good. This caused me to remember a separate memory.

In Burma where I grew up, mosquitoes were a menace. Every night we slept under a dome of mosquito net which my mom set up. Like a superhero, she killed any passer-by mosquitoes by clapping her hands really fast and crushing them. Even then, I got bit by a few if my arm was outside the net during sleep. When I woke up in the morning, I would see these reddish bumps on the arm and felt like scratching. It was pleasurable to scratch especially around the area of the bump. My mom would go to a pharmacy and bought an antihistamine cream to alleviate the itching. So why? Why did the itch sensation feel so good?

The human skin is a marvellous organ. It is constantly monitoring the moisture and the chemistry of the skin as well as the bacteria that reside on them. If any threatening change is detected, the interoceptive nerves on the skin react immediately by inducing either mild pain or itching sensation. Itch is a localised skin phenomenon that sometimes arises with no explanation whatsoever. The feeling of itch is generated by a unique set of neurons that are unmyelinated. These are separate from pain and feel qualitatively different. If you scratch the itchy skin gently and slowly, the mild pain receptors override the sensation and the signal goes directly to the pleasure centers of the brain that releases endorphins, serotonin and other hormonal goodies. Many things can cause an itch. The most common cause is dry skin. The skin doesn’t like it if it is not properly moisturized because dry skin is susceptible to an outside attack. Most bacteria and bugs that live on the skin are harmless but certain ones can cause infections and rashes. The immune response to their attack can cause itching. If you have an allergic reaction to certain substances or metals, they can cause itching too. Additionally, hormonal changes during puberty or pregnancy and even psychological states such as nervousness, fear and OCD can cause unexpected itching. Or if you are trying to focus on a certain task, the skin can become itchy on places you can’t reach. This is especially annoying during cooking. When I am cutting the ingredients, my nose or cheek can become itchy. I have to use my shoulder to scratch it which is not ideal. Even now as I am writing these words, the left side of my nose is starting to become itchy. In terms of a mosquito bite, the female mosquito releases a clever mix of saliva that prevents the blood from clotting so she can extract as much blood as possible. The xenophobic immune system does not like any foreign substances entering the body. So, it causes an inflammation to repair the damage as soon as possible which explains the red bumps. The engorgement of blood around the area is what makes it itchy.

The simplest pleasure in life is having a good scratch. You know the itch will return even stronger than before. It is often used as an analogy to talk about other kinds of addictive pleasures like drugs or gambling. Those who have chronic itching condition are believed to have low self control. You gotta be careful not to become addicted to the pleasure. Everyone has a favourite spot where they enjoy scratching like the ankle, knee, elbow, nose etc. The skin will degrade over time from scratching it too often. Reddish eczema spots start to appear that look disgusting to the bystander. The spots feel very sensitive with a little bit of sharp pain sensation. Often it is hard to focus on cognitively demanding tasks like writing when the head is itchy. The dandruff build up on the scalp demands attention. It feels like little insects crawling on the head. One tends to lose temper during an itchy episode like this. The antidote is a good shower and some lotion. One more fascinating fact is that just like laughing the itch response is contagious to other people. When an empathetic person sees someone scratching, their skin also activates the feeling of itch around the same area. Especially if that someone is a close member of kin. Inside the brain, the touch map is activated as well as the mirror neurons that mimic the sensation so long as he/she is within the field of view. This is why scratching the inappropriate places in public is rude and makes everyone in the immediate vicinity uncomfortable. Their brains are also activating the itch response in those areas. Over time, a biological phenomenon is translated into social rules and customs that everyone has to obey. The sense of touch has this power.

No matter who you are whether you are a billionaire or a homeless, a middle class or a poor person, life is unbearable. Yes, it is important to be grateful of the good things in life. But you can’t deny the fact that there are absolutely horrific things in existence that beg the question of why we should be alive in the first place. They can be loneliness, poor health, mental illness, chronic pain, discrimination, debt, crime, war, natural disasters or plain bad luck. Not only that, it is the little awkward things in the experience of living that are annoying. Forcing yourself to make a conversation with someone you do not like and then suddenly becoming itchy on the back. Feeling the need to defecate during a dinner date. There is no one on this earth who have not suffered or felt regret in one way or another due to the humiliations associated with the sense of touch. It is this human condition that unites us.

For billions of years, you were never alive. Until you came out of your mother’s womb, you never existed. Once you were born as a human being and grew up to understand your place in life, you couldn’t help but wonder why you were born in the first place. Was it not better to be unconscious? Was it not better to never have been born? The counterweight to why being alive is worth it, is the pleasure of touch. Touch confirms our existence. We have the ability to interact with the world and the people around us with the boundary of our being. We are children of the universe and so we have evolved the touch senses to distinguish its secrets. Deprive a person of touch and life will have no meaning. It is the minimum requirement to feel alive. After all, life is just a lease. Eventually you will have to give it up for someone else. During this short time of being alive, the pleasure of touch carries us to heaven.

Touch Pleasure Model - Part 1

Exteroception

Interoception

Further Reading

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