It sure doesn’t feel like predictive processing

Reddit user @Daniel_HMBD kindly re-wrote some parts of my previous essay to make it clearer. I am now posting this corrected version here.

Broad claim: The brain (conscious or unconscious) “explains away” a large part of our surroundings: the exact motion of a tree or a blade of grass as it sways gently in the wind, the exact motion of a human as they walk, etc. If we could force our brain to make predictions about these things as well, we’d develop our scientific acumen and our understanding of the world.

How can I understand the motion of a blade of grass? The most common answer is “observe its motion really closely”. I’ve spent considerable amounts of time staring at blades of grass, trying to process their motion. Here’s the best that I could come up with: the blades are demonstrating a simple pendulum-like motion, in which the wind pulls the blade in one direction and its roots and frame pull it in the opposite direction. Observe that I didn’t end up observing the tiny details of the motion. I was only trying to fit what I saw with what I had learned in my Physics course. This is exactly what our brain does: it doesn’t really try to understand the world around us. It only tries to explain the world around us based on what we know or have learned. It does the least amount of work possible in order to form a coherent picture of the world. Let me try and explain this point further in a series of examples.

When ancient humans saw thunder and lightning in the sky, they “explained away” the phenomena by saying that the Gods were probably angry with us, and that is why they were expressing their anger in the heavens. If there was a good harvest one year, they would think that the Gods were pleased with the animal sacrifices they’d made. If there was drought despite their generous sacrifices, they would think that the Gods were displeased with something that the people were doing (probably the witches, or the jealous enemies of our beloved king). Essentially, they would observe phenomena, and then somehow try to tie it to divine will. All of these deductions were after the fact, and were only attempts at “explaining away” natural phenomena.

When pre-Renaissance humans observed their seemingly flat lands and a circular sun rising and setting everyday, they explained these observations away by saying that the earth was (obviously) flat, and that the sun was revolving around the earth. They then observed other stars and planets moving across the skies, and explained this by saying that the planets and stars were also orbiting us in perfectly circular orbits. When the orbits were found to be erratic, they built even more complicated models of celestial motion on top of existing models in order to accommodate all that they could see in the night skies. They had one assumption that couldn’t be questioned: that the earth was still and not moving. Everything else had to be “explained away”.

When we deal with people who have a great reputation for being helpful and kind, we are unusually accommodating of them. If they’re often late, or sometimes dismissive of us, we take it all in our stride and try to maintain good ties with them. We explain away their imperfect behavior with “they were probably doing something important” and “they probably mean well”. However, when we deal with people who we don’t think very much of, we are quick to judge them. Even then they’re being very nice and courteous to us, we mostly only end up thinking “why are trying so hard to be nice” and resent them even more. We explain away their behavior with “they probably have an ulterior motive”.

Essentially, our brain sticks to what it knows or understands, and tries to interpret everything else in a way that is consistent with these assumptions. Moreover, it is not too concerned with precise and detailed explanations. When it sees thunder in the skies, it thinks “electricity, clouds, lightning rods”, etc. It doesn’t seek to understand why this bolt of lightning took exactly that shape. It is mostly happy with “lightning bolts roughly look and sound like this, all of this roughly fits in with what I learned in school about electricity and lightning, and all is going as expected”. The brain does not seek precision. It is mostly happy with rough fits to prior knowledge.

Note that the brain doesn’t really form predictions that often. It didn’t predict the lightning bolt when it happened. It started explaining away with lightning bolt after it was observed. What our brain essentially does is that it first observes things around us, and then interprets them in a way that is consistent with prior knowledge. When you observe a tree, your eyes and retina observe each fine detail of it. However, when this image is re-presented in the brain, your “the tree probably looks like this” and “the leaves roughly look like this” neurons fire, and you perceive a slightly distorted, incomplete picture of the tree as compared to what your eyes first perceived.

In other words, your brain is constanly deceiving you, giving you a dumbed-down version of reality. What can you do if you want to perceive reality more clearly?

Now we enter the historical speculation part of this essay. Leonardo da Vinci was famously curious about the world him. He made detailed drawings of birds and dragonflies in flight, of the play between light and shadows in real life, futuristic planes and helicopters, etc. Although his curiosity was laudable, what was even more impressive was the accuracy of his drawings. Isaac Newton, another curious scientist who made famously accurate observations of the world around him, was unmarried throughout his life and probably schizophrenic. John Nash and Michelangelo are other famous examples.

I want to argue that most neurotypicals observe external phenomena, and only after such observations try to explain these phenomena away. However, great minds generate predictions for everything around them, including swaying blades of grass. When their observations contradict these predictions, they are forced to modify their predictions and hence understanding of the world. Essentially, they are scientists in the true sense of the word. What evidence do I have for these claims? Very weak: n=1. Most of what I do is observe events, concur that this is roughly how they should be, and then move on. Because I can explain away almost anything, I don’t feel a need to modify my beliefs or assumptions. However, when I consciously try to generate predictions about the world around me, I am forced to modify my assumptions and beliefs in short order. I am forced to learn.

Why is it important to first generate predictions, and then compare them with observations? Let us take an example. When I sit on my verandah, I often observe people walking past me. I see them in motion, and after observing them think that that is roughy how I’d expect arms and legs to swing in order to make walking possible. I don’t learn anything new or perceive any finer details of human motion. I just reaffirm my prior belief of “arms and legs must roughly swing like pendulums to make walking possible” with my observations. However, I recently decided to make predictions about how the body would move while walking. When I compared these predictions with what I could observe, I realized that my predictions were way off. Legs are much straighter when we walk, the hips hardly see any vertical motion, and both of these observations were common to everyone that I could see. Hence, it is only when we make prior predictions that we can learn the finer minutae of the world around us, that we often ignore when we try to “explain away” observations.

I was on vacation recently, and had a lot of time to myself. I tried to generate predictions about the world around me, and then see how they correlated with reality. Some things that I learned: on hitting a rock, water waves coalesce at the back of the rock. Leaves are generally v-shaped, and not flat (this probably has something to do with maximizing sunlight collection under varying weather conditions). People barely move their hips in the vertical direction while walking. It is much more common to see variations in color amongst trees than height (height has to do with availability of food and sunlight, while color may be a result of random mutations). A surprisingly large number of road signs are about truck lanes (something that car drivers are less likely to notice, of course). Also, blades of grass have a much smaller time period than I assumed. Although I don’t remember the other things I learned, I think that I did notice a lot of things that I had never cared to notice before.

Can I use this in Mathematics (for context, I am a graduate student in Mathematics)? In other words, can I try to make predictions about mathematical facts and proofs, and hopefully align my predictions with mathematical reality? I do want to give this a serious shot, and will hopefully write a blog post on this in the future. But what does “giving it a serious shot” entail? I could read a theorem, think of a proof outline, and then see whether this is the route that the argument goes. I could also generate predictions about properties of mathematical objects, and see if these properties are true about these manifolds. We’ll see if this leads anywhere.

So forming predictions, which really is a lot like the scientific method, is naturally a feature of people of certain neural descriptions, who went on to become our foremost scientists. It is yet to be seen whether people without these neural descriptions can use these skills anyway to enhance their own understanding of the world, and hopefully make a couple of interesting scientific observations as well.

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Graduate student

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