For most of the last century, we were taught a comforting story about the brain: an ancient, animal part reacts on instinct, while a newer, rational part keeps it in check. Fear happens to you.
It’s a tidy story. It’s also not how the brain actually works.
I’ve spent a lot of time studying the work of Dr. Lisa Feldman Barrett, a neuroscientist who has studied emotion for over three decades, because her research changed how I understand what happens in EMDR and IFS sessions. It also clicked for me personally, because other models and theories didn’t quite explain all the intricacies and nuances I have experienced and seen in others.
Here and here are two short videos that explain this neuroscience and how we can use it to make the changes we wish to see in our lives.
Emotions aren’t triggered. They’re constructed.
Your brain doesn’t “detect” fear the way a smoke alarm detects smoke. It constantly receives raw, ambiguous signals — a tug in your chest, a loud noise, someone’s tone of voice — and has to guess what they mean based on your past experience. It knows the outcome (a racing heart) but not the cause (panic? excitement? caffeine?). So, it reaches into memory and reconstructs the most likely explanation, moment to moment. That reconstruction — built from prior experience — is the emotion.
In other words: emotions aren’t reactions to the present. They’re predictions built from the past. Instead of waiting for sights or sounds to reach you, your brain uses your memory and past situations to predict what you are about to experience before it actually happens. This guessing game is the main way your brain manages your body and creates everything you think, feel, and see. Your brain’s main job is not actually thinking or feeling — it is managing your body’s energy (called allostasis) by predicting your needs before they happen.
Broadly, an emotional response does several jobs at once: it makes sense of raw sensation, points you toward an action, mobilizes your body’s resources for that action, and helps you connect with and signal to the people around you. Seen this way, an emotional reaction isn’t random or “wrong” — it’s your system’s best current guess about what to do next.
Why this matters for EMDR + IFS
EMDR helps the brain update outdated predictions. A trauma survivor’s brain may have learned that a certain sound or bodily sensation means danger — and keeps applying that old prediction long after the danger has passed. Reprocessing gives the brain new information so it can revise the prediction it’s been running on autopilot.
Protector parts make more sense through this lens too. A protector isn’t broken — it formed a prediction, usually early and for good reason, and it’s still running that prediction today. Getting curious about a part, rather than fighting it, helps your system gather new evidence so the prediction can update — and the part can finally stand down.
The takeaway
None of this means your feelings aren’t real, or that you can just think your way out of anxiety or grief. But the meaning your brain assigns to a feeling can shift with practice and the right support you give yourself. That’s the work — not fighting your brain’s predictions, but helping it build better ones.