The hierarchy — sometimes called an exposure ladder — is the plan for treatment. It lists situations, thoughts, objects and actions that trigger the obsession, each rated 0 to 100 for how much distress approaching it would cause. Then you work up it.
Building it’s usually session two or three, and it takes longer than expected because a good one is specific. Not “germs” but “touch the handle of the third-floor bathroom door and then eat a sandwich without washing.” Vague items can’t be done, and can’t be repeated identically, which matters.
What goes on it
Everything you avoid, everything that triggers a compulsion, and everything you can only do with a safety behavior attached. Which means the hierarchy is essentially the inverse of your avoidance list — a good reason to write that first.
It should include the things you do only when someone else is present, or only in a certain order, or only after checking. Those partial versions belong on the ladder as their own steps.
How the numbers work
Rate each item for anticipated distress out of 100. Do not agonise; the numbers are relative to each other, and consistency matters more than accuracy. Most people end up with something spread from around 20 to 100, and gaps in the middle are worth filling in, because a jump from 40 to 80 is where people stall.
You start around 40 to 50 — high enough to be a real exposure, low enough to be repeatable daily. Not at the bottom, which teaches little, and definitely not at the top.
Two things that have changed in modern ERP
Strict order isn’t required. Older protocols insisted on completing each rung before moving up. Newer inhibitory-learning approaches suggest varying the order, mixing difficulty, and changing context deliberately — because what you’re trying to build is a new learning that generalises, and variability helps that more than orderly progression does.
Habituation isn’t the target. Older ERP asked you to stay in an exposure until distress halved. The current emphasis is on violating the expectation instead: predict what you think will happen, do the exposure, and see what actually happens. Anxiety coming down is welcome and isn’t the measure of success — being able to do it while anxious is.
Revising it
The hierarchy is a working document. Items get re-rated as they become easier. New ones surface once you start paying attention, particularly avoidances you had rationalised. And if a theme shifts, which OCD does, you build the relevant part again.
The item people leave off
Almost everyone omits one — the exposure they have privately decided they will never do. It’s worth putting it on the list anyway, at 100, without committing to it. Naming it removes its special status, and a surprising number of people arrive at it in month four and find it has come down to a 55 on its own, because the learning generalised from everything below it.