Reality Remix: Your Brain's Masterful Illusion
Imagine your brain as a harried film editor, frantically splicing together a movie called "Reality" from an overwhelming flood of sensory footage. Its job? To create a coherent narrative from chaos, all under the pressure of an unforgiving deadline - your imminent moment of awareness. Seems implausible?
Reconstructing Reality
To begin with, the vibrant, textured world you experience is actually a meticulous reconstruction within the confines of your skull. As neuroscientist David Eagleman poetically puts it, your brain is "locked in a vault of silence and darkness." You will never experience actual reality because you have no direct access to it. Your brain is essentially a highly sophisticated guesser, piecing together its interpretation of reality from electrical impulses sent by your senses. The senses are fact-checkers, looking for anything unexpected. enabling your brain to constantly adapt its model of reality. It's why you might do a double take when you see a car driving on the wrong side of the road – your brain is frantically cross-checking its 'normal traffic patterns' database.
To add to the challenge, your senses capture but a sliver of reality. For instance, your eyes capture a mere 0.0035% of the electromagnetic spectrum - that's like trying to follow the plot of "War and Peace" while reading every 28,571st word. (1) Yet somehow, your brain weaves this sparse data into a seamless tapestry of experience. And it works, since we are alive and well to tell the tale. Just like other animals, evolution has shaped us to perceive those things that matter to our survival and ignore the rest. Our version of "reality" is vastly different than that of other species.
Meaning vs Truth
Your brain seeks to automatically "fill in the blanks" through a process known as visual completion, which plays a fundamental role in recognizing objects, shapes, and patterns. The brain's perception relies to a large extent on previous experiences and other "top-down" shortcuts, as relying on a "bottom-up" approach would be too slow and often yield vague or incomplete imagery.
Your brain seeks closure in deducting the whole, regardless of missing individual parts. Artists are well familiar with this principle and use it to bring unity to their painting, while leaving room for individual interpretation. Your brain seeks to make sense of what it sees, rather than seeking the truth. It acts like a Hollywood producer, not particularly concerned with objective truth, instead it's laser-focused on distilling all the data into a narrative that is gripping and useful.
This leads to some amusing quirks in perception. Take the famous checkerboard illusion below. Go ahead, stare at those squares. I'll wait. Convinced they're different shades? Your brain is currently staging a rebellion against reality.
The two squares that appear drastically different in shade are actually identical. Your brain, drawing on its vast experience with light and shadow, insists on seeing what it expects rather than what's actually there.
Square A looks much lighter than square B - though in reality it is similar. Our brain identifies the centrally lit portion of the board, with shadows on the edges. It interprets B as a dark square in the light, and A as a lighter square in the shadow. This is how we interpret the picture, based on all our previous experience dealing with light and shadows.
The side-by-side
squares show the reality: A is as dark as B.
Credit: Wuhazet - Henryk Zychowski
The Great Neuronal Pruning: Use It or Lose It
Our neurocircuitry is profoundly shaped by what we learn as we go through life. Your brain starts life as a forest of 100 billion neurons, then engages in a ruthless arboreal cull. By adulthood, you're down to a mere 86 billion neurons, and a synaptic density in your cortex that is less than two thirds of what it was when you were a toddler. (2) This pruning process, far from being destructive, is actually the brain's way of learning about and adapting to our experience of the world. It's like your neural circuitry is playing an intense game of "Survivor," with only the most useful connections making it to the final round. The overabundance of neurons and connections in early childhood provides the most flexibility to adapt, but it also turns out to be a highly effective way to build robust and very efficient networks.
The Perils of Pattern-Matching
Our brains are so eager to find patterns that they sometimes completely miss important information. The iconic video below is a great illustration of this - if you haven't seen it before, watch the video and count the number of passes by players with white T-shirts - you will likely be very surprised by the outcome. (3)
Perfect Perception: A Pipe Dream
In conclusion, your perception of reality is less a faithful recording and more an imaginative interpretation to make sense of what you see and sense. Your brain, that marvelous organ, is constantly engaged in a high-stakes improv performance, turning sparse sensory data into the rich, meaningful world you inhabit. It's a reminder that the most convincing illusions are often the ones we create for ourselves. (4)
Once language emerged, this primordial urge to make sense of the world led to the development of storytelling, which came to play a foundational role in human societies, as we will see next.
(2) Core Concept: How synaptic pruning shapes neural wiring during development and, possibly, in disease - PMC (nih.gov)
(3) This experiment gives new meaning to the Elephant in the Room! The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us
(4) The image is that of Magritte's famous painting questioning our assumptions about the nature of reality.