Your brain hasn't changed since you were a registrar

When I show a senior colleague one of the cognitive aids I've built, there's one reaction I get more than any other. They turn the phone over in their hand, nod, and say something like: “this would be great for a registrar. I wish I'd had this when I was training.”

It's meant as a compliment. I take it as one. And it is, word for word, the problem I'm trying to solve.

Buried in that sentence is an assumption we almost never say out loud: that a tool like this is something you grow out of. That somewhere between registrar and consultant, expertise doesn't just sharpen your judgement, it removes the need for the tool in the first place. The aid was scaffolding, and seniority is what you replace it with.

It isn't. And the reason goes deeper than the tools, because it's really a claim about what expertise is.

Passing your fellowship exam doesn't give you more working memory.¹ The structure of the human brain doesn't change because you've made consultant. A consultant at 0300 holds roughly the same number of things in conscious attention as the registrar standing next to them, which is to say, not many. Seniority doesn't expand the workspace. It changes what you spend it on. And that's the distinction the “great for a registrar” reaction gets wrong: it assumes expertise hands you spare capacity, when expertise was never extra capacity. It's a better way of spending the capacity you already had, and always will have. The tools aren't covering for inexperience. They're covering for being human, and you don't grow out of that.

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Where the assumption comes from

We build the assumption in early. From first year, exams reward unaided recall, and the doctor who can quote the trial, the dose and the guideline from memory is held up as the model of what a clinician should become. That's bizarre when you stop to think about it, because recall is precisely the function we know to be fragile. It degrades with fatigue, interruption, stress and time of day, which is to say, under exactly the conditions in which medicine is actually practised. We've organised the status hierarchy of the profession around the brain's least reliable feature.

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The line we've already crossed

And here's the strange part: we've already conceded the principle. Nobody expects you to carry amikacin dosing in your head, or the titration table for a bivalirudin infusion. The number lives in the guideline. What you're expected to know cold is the pharmacology: why the aminoglycoside needs a level, what renal failure does to clearance, when the drug is the wrong choice. The number itself we externalised years ago, and nobody calls it deskilling.

So the principle is settled. Understanding belongs in the clinician, arbitrary detail belongs in the system. The only live question is where the line sits, and we've drawn it in strange places. The arrest algorithm belongs in your head. But the ECMO cutoff, 60 minutes of CPR or 75? The apnoea threshold, a rise of 20 or 25? No amount of seniority makes those stick, and nothing is gained by holding them in a human memory instead of on a screen, except one more chance to get them wrong.

Memory has another job, too, one we rarely name. It holds your place. You arrive at an arrest, take a thirty-second handover, sort the rhythm, then turn to reversible causes. Hypoxia, being addressed. Potassium, pending on the gas. Two items in, the next rhythm check is called. Or someone asks about access. Or anaesthetics arrive wanting a handover, and the family appear at the door. The thread is gone, and you come back to it a minute later with questions instead of answers: what have I already excluded, what's still pending, what was I about to ask for? The algorithm was never the hard part. Holding your place in it while the room keeps taking your attention away is, and that's a working memory problem twenty years of experience barely touches. The consultant loses the thread to the same interruptions the registrar does. They're just better at hiding the moment it happens.

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The exam that proves the point

My favourite example is the exam itself. As part of intensive care fellowship, you're expected to perform brain death testing from memory. Consider what brain death testing actually is. It is not an emergency. There is no time pressure. The guideline is written down and freely available on the ANZICS website.² The patient is not getting any more dead. There is no situation in real practice where the right thing to do is run it from memory rather than with the protocol open in front of you. And yet that is exactly what the exam asks for, and the message it sends is that a real expert shouldn't need to look it up.

Think about what genuinely needs a doctor in that room. Not the checklist. The thresholds and exclusions are in the guideline, and the guideline doesn't get tired or skip a line. What needs a doctor is everything around it. Talking to the family. Sitting with a mother looking at a chest that still rises and falls, trying to understand how this can be death. Holding that space, then gently opening the conversation about organ donation. Those are the things only a clinician can do, and they're exactly the things that get crowded out when part of your attention is busy trying to remember whether the apnoea threshold is a rise of 20 or 25.

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What experience actually buys you

This is usually where someone objects: but experience matters. It does, enormously. Experienced clinicians chunk.⁴ The rhythm strip that costs a junior five slots of working memory costs a consultant one, because twenty years of pattern exposure has compressed it into a single recognisable object. That compression is real, and it's most of why experts are fast. But look at what chunking is: compression of the familiar. Arbitrary numbers, rarely used thresholds, the specific state of this arrest on this night, none of it is familiar, so none of it compresses. Expertise lets you spend your handful of slots more wisely. It does not hand you an extra slot. On a bad night, under interruption and fatigue, the consultant's working memory fills exactly like everyone else's. It just fills with more expensive things.

So the reaction has it backwards. What the tools offload is precisely the part that never compresses, no matter how senior you get, which frees the capacity that goes to the judgement only a clinician can bring. That's what the aids I build are for: they hold what doesn't need a doctor, and force the step that does. None of them decides anything.

And the way we build systems keeps missing this. A 2025 study in BMJ Quality & Safety analysed three hundred serious incident investigations across three Australian states.³ Of the contributing factors, 47 per cent sat at the level of the individual people involved. Of the recommendations that followed, only 6 per cent were rated strong: the kind of structural change that doesn't depend on humans behaving better next time. The rest were overwhelmingly policy reviews, training and education. We keep meeting the limits of human cognition by asking humans to cognate harder. We keep reaching for the weakest interventions on the list. A cognitive aid isn't a set of training wheels you take off once you're good enough. It's an acknowledgement that some things never belonged inside a human brain in the first place, and no amount of seniority changes which things those are.

So when a senior colleague tells me one of these would have been great for a registrar, here's what I've slowly learned to say out loud: it would be great for you. Not because you're not good enough. Because you're human, the conditions are hostile, and the brain you're using tonight is the same one you had as a registrar. The only thing that's changed is that somewhere along the way, we started expecting you to pretend otherwise.

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