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Brain’s best guess!
Have you ever been so lost in a daydream that you almost forgot you were sitting in a chair? Or perhaps you’ve woken up convinced a dream was real for a few seconds? We all experience moments where the line between what’s happening and what we’re imagining gets blurry. But how does your brain usually keep them apart?
New research suggests the answer lies in a simple concept: volume!
The Shared Hardware Problem
Your brain is incredibly efficient. To save energy, it uses the same neural circuits to see the world and to imagine it. When you picture a red apple, the part of your brain that processes the colour red lights up, just as it does when you actually see one. This is great for creativity and planning, but it creates a glitch: if the hardware is the same, how does the brain know which signal is coming from the outside world and which is coming from inside your head?
Who’s Listening?
Scientists at University College London discovered that the brain solves this problem by measuring the “loudness” of the signal. A specific region called the fusiform gyrus acts like a volume knob. It doesn’t care if the sound is coming from your eyes or your own brain; it just measures the total strength of the sensory activity.
In a recent study, volunteers looked for faint patterns on a screen while simultaneously imagining similar patterns. When the imagined pattern matched the real one, the brain’s “volume” spiked. The fusiform gyrus detected this combined strength. If the signal was loud enough, the brain declared, “This is real!” If it was muffled, it recognised it as just a thought.
The Frontal Judge
So, who makes the final call? While the fusiform gyrus measures the volume, other parts in the front of the brain, specifically the anterior insula, act as the judge. They receive the volume reading from the fusiform gyrus and apply a threshold. If the signal is strong enough, the brain treats it as real. If it stays below that level, the brain recognizes it as imagination.
This explains why vivid daydreams can feel so real. When your internal simulation is strong enough, it pushes the volume past the threshold, tricking your brain into accepting a phantom as fact.
Why This Matters
This discovery changes how we understand reality. It’s not that your brain uses a magical “truth label” to mark thoughts as real or imagined. Instead, reality is a best guess based on signal intensity. Most of the time, the math works perfectly. But when the internal signal becomes too strong, or the threshold too low, the line blurs.
Reality Is a Best Guess
This helps explain why reality monitoring sometimes fails, for example during hallucinations or intense memories. It reminds us that what we call “reality” is a carefully constructed inference, weighted by the sheer force of our own neural activity. We aren’t just passive observers of the world; we are active participants, constantly balancing the noise of our minds against the silence of the void.
Author: Vivek
Buddy & Editor: Rick Arends
Translation: Wieger
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