The Objectivity of Subjectivity: A Model of the Brain’s Valuation System

The Great Debate: Is Your "Taste" Just Random Noise?

Imagine you are walking through a massive, bustling marketplace. One person stops to admire a bright, loud neon sign, while another walks right past it, captivated by a quiet, mossy stone. For centuries, philosophers have argued over whether these differences in what we like—our "values"—are just random quirks of personality (subjectivity) or if there is a deeper, universal truth we are all chasing (objectivity). In the past, many thinkers and artists decided that personal taste was a bit frivolous, a messy side effect of being human that we should try to ignore in favor of "real" facts. But what if that "messiness" isn't a mistake at all? What if it's the main feature?

This question sits at the intersection of neuroscience, psychology, and computer science. To understand it, we need to know a few basic ideas. First, our brains are constantly trying to predict how good or bad an outcome will be before we even experience it; this is called valuation. Second, the brain learns these predictions through reinforcement learning, a trial-and-error process where we get "rewards" (like food or praise) or "punishments" (like pain or disappointment) and adjust our future choices accordingly. Finally, the world is full of noise—random, unpredictable changes in our environment and our bodies. Usually, we think of noise as something that ruins our ability to see the truth. But this paper asks a wild question: What if that noise is actually the secret ingredient that makes us all unique?

The Brain's "Taste" Simulator

In this study, Norberto Grzywacz from Loyola University Chicago didn't just ask people what they liked; he built a digital brain to find out how values are formed. Think of this computer model as a super-smart video game character that learns to play a game by trying different moves and seeing what happens. The researchers programmed this digital brain with the same rules real brains use: it takes in sensory information, feels a bit of motivation (like hunger or curiosity), and learns to predict rewards.

The team ran massive simulations, letting their digital agents play out 100,000 rounds of learning. They wanted to see if two identical agents, starting with the exact same settings, would eventually agree on what was "good" and what was "bad."

The "Cloud" of Differences
The results were surprising. Even when the agents started with the same settings, they didn't end up at the same spot. Instead, their values drifted apart, forming what the researchers call a "stochastic cloud." Imagine two hikers starting at the same base camp. If the path was a straight, smooth road, they would likely end up at the same peak. But in this simulation, the path was a bumpy, foggy mountain. Because of tiny, random bumps in the road (the "noise" of the world and the brain), the hikers took slightly different turns. Over time, these small differences added up, and they ended up at different, yet equally valid, spots on the mountain. The computer showed that this "drift" wasn't just random chaos; the agents' values stayed different for thousands of iterations, suggesting that our brains are designed to keep our values unique.

The Invisible Trampoline
Here is where it gets even more interesting. The researchers discovered that the brain doesn't just settle on one single "perfect" value. Instead, it settles on a whole surface—like a trampoline or a curved sheet of fabric. Think of it this way: if you drop a marble on a flat table, it stops in one spot. But if you drop it on a curved trampoline, it might roll to the edge, or the middle, or the side, depending on exactly how you let go. The computer model showed that the brain's "perfect" values exist on this curved surface. Once the learning process reaches this surface, random noise (stochastic resonance) pushes the values around, making them bounce to different points on that same surface. This means that even if two people are learning the same thing, they might land on different "sweet spots" simply because of the tiny, random jitters in their lives.

The Boosters: Body and Society
The study also tested what happens when you add real-life factors.

• Motivation: The researchers tweaked the "motivation" settings, which come from body signals like hunger or energy levels. They found that high motivation and low motivation pushed the agents' values in different directions. It's like two people listening to the same song: one is dancing with high energy, while the other is tired and moving slowly. They hear the same music, but their experience of it is totally different.
• Society: They also simulated two different "societies" with different average environments. One society had a "standard" world, while the other had a world with 33.3% lower sensory inputs. The result? The people in these two societies developed significantly different values. A person living in a desert learns to value water differently than someone living in a jungle, and the computer showed this difference was baked into the learning process itself.

The Big Takeaway: Your "Subjectivity" is Objective

So, what does this all mean for us? The paper suggests that the differences between people aren't just random accidents or flaws in our thinking. Instead, the brain's learning system is built to create diversity. Because our brains adapt to our unique life contexts—our specific bodies, our families, our cultures, and the random noise of our daily lives—our values should be different.

The authors propose that what we call "subjectivity" (your personal taste) might actually be "objective" in a deep, evolutionary sense. It is an objective feature of a brain that is trying to optimize itself for a specific, unique life. If you and your best friend disagree on what is beautiful or important, it's not because one of you is "wrong" or "broken." It's because your brains have successfully adapted to your unique paths.

The study doesn't claim that any value is acceptable (the authors note that values leading to crimes are still bad), but it does suggest that the "disorder" of human minds that puzzled thinkers like Einstein might actually be a sensible, designed mechanism. The "messiness" of our personal tastes is the brain's way of ensuring that we are all different, allowing us to fit into the complex, varied world we live in. In short, your unique perspective isn't a bug; it's a feature.