The Dark Room

Your brain is listening to your body.

It has no choice. It exists in a dark room with no windows or doors.

Fortunately, 80% of the nerve fibres that make up your vagus nerve (the largest nerve in your body) carry signals from your body to your brain. It's a highway with traffic flowing overwhelmingly in one direction.

Furthermore, the nerves that transport signals from the retina to the visual cortex are vastly outnumbered by the connections that feed predictions from various other parts of the brain.

Your brain is a prediction machine.

It is constantly scanning the world, making sense of patterns, and guessing what will happen next.

Your brain doesn't just use the incoming data to make those predictions.

According to an increasing number of neuroscientists, the brain constructs an elaborate simulation of the world based on expectations and previous experiences as much as on raw data hitting the senses. Most of the time, these simulations align with reality—but when they don’t, they can dramatically shape how we perceive the world.

If you're holding a baby and bang your hand against the wall, followed by holding the baby's head, the baby will start to cry. The baby predicts that it was hurt, even though the pain never actually occurred. This is how trauma shapes perception—children learn to brace for impact long before anything happens.

“We see what we predict, rather than what’s out there.”
— Moshe Bar

Before a child walks into a room, their brain (sitting in that dark room) has already built simulations of what might be there. If their past has been filled with neglect, rejection, or abuse, their mind fills in those gaps with fear-based expectations. This is why a child with trauma might flinch at a kind touch, why they shut down when offered help, or why they explode at a simple request.

Their brain isn’t reacting to the present—it’s predicting based on past patterns.

Predicting What We See

Consider the duck-rabbit illusion—in one study, 90% of people saw a bird (looking to the left) in October, but at Easter, only 20% saw a bird. The majority could now see a rabbit (looking to the right). The wider context influenced what was seen.

Now imagine that same principle applied to a child shaped by trauma—their brain, too, is choosing between different interpretations of the world. But instead of choosing between a duck or a rabbit, they choose between safety or threat—and their past tells them to expect the worst.

“We don’t just passively perceive the world, we actively generate it. The world we experience comes as much, if not more, from the inside out as from the outside in.”
— Anil Seth

The good news is that predictions can change. Safe, consistent relationships retrain the brain over time. When we respond to a child’s fear with connection instead of control, we rewrite their expectations about the world and its people.

It’s not about fixing behaviour but changing their brain's predictions.

How do we build environments where children’s brains can start predicting safety instead of fear? Reply and let me know your thoughts.

Primary sources for this piece

¹ The Expectation Effect by David Robson
² Book Review: Surfing Uncertainty, Slate Star Codex