How many items should an exposure hierarchy have?

Ten to twenty is typical. What matters more than the count is the spacing: the gap between consecutive rungs should be small enough that the next step always feels possible.

Where should I start on the hierarchy?

Somewhere genuinely uncomfortable but doable, often around 3 to 4 out of 10 on a distress scale. Starting too low wastes weeks; starting too high usually ends in an abandoned exposure, which teaches the wrong lesson.

When do I move up a rung?

When the current rung has stopped surprising you - you can do it without the compulsion, and your expectation of disaster no longer matches what actually happens. Many therapists look for a meaningful drop in the distress rating across repetitions rather than a specific number.

How to Build an Exposure Hierarchy (With Worked Examples)

An exposure hierarchy is a list of situations that trigger your OCD, each rated for how much distress it causes, ordered from most manageable to hardest. It exists to turn the useless instruction "face your fears" into a sequence of specific, achievable steps. In [ERP](/blog/what-is-erp-exposure-response-prevention), building the hierarchy is usually the first real piece of work you and a therapist do together.

Step 1: list the triggers, not the fears

Write down situations, not abstractions. “Contamination” is not a hierarchy item. “Touching the handle of the bin in my kitchen and not washing for an hour” is.

Cast wide. Include:

Situations you avoid. The route you no longer take, the person you stopped visiting, the word you will not type.
Situations you endure only with a ritual. Anything you can do, but only if you check, wash, count, or silently repeat something afterwards.
Thoughts and images. For obsessions that are mostly internal, the trigger may be deliberately bringing the thought to mind rather than any external situation.
Small everyday things. The mundane items are where you start, and they are easy to forget precisely because you have automated the ritual around them.

Aim for thirty or forty raw items before you filter. It is much easier to cut than to invent.

Step 2: rate each one

Give every item a number from 0 to 10 on a distress scale. The convention is SUDS, where 0 is completely calm and 10 is the worst distress you can imagine.

Rate honestly rather than aspirationally. The number you want is “how bad would this actually be for me, right now, if I did it without the compulsion.” Two things to keep in mind:

Rate the item with response prevention included. Touching a doorknob is a 2 if you can wash afterwards and an 8 if you cannot. The second number is the real one.
Do not agonise. A rough number that is close is worth far more than a precise number you spent twenty minutes deriving. Deriving it precisely is, itself, a compulsion.

Step 3: sort and fill the gaps

Order the list by rating. Then look for jumps. If you have several items at 3, nothing at 4 through 6, and then a cluster at 7, you have a problem: the step from 3 to 7 is the step most people fail at, conclude ERP does not work, and stop.

Fill gaps by varying one dimension at a time:

Duration. Two minutes without washing, then ten, then an hour.
Proximity. Standing near it, touching it with one finger, holding it, touching your face afterwards.
Certainty. Doing it while you can still see the stove, then from the next room, then after leaving the house.
Audience. Alone, then with someone who knows, then with someone who does not.
Support. With the therapist present, then alone.

Two worked examples

Contamination

SUDS	Exposure
2	Touch the outside of my own front door, wait 5 minutes before washing
3	Touch the front door, wait 30 minutes
4	Touch a shared stair rail in the building, wait 30 minutes
5	Touch the stair rail, then eat a snack without washing first
6	Use a public bus handrail, no hand sanitiser, for the rest of the journey
7	Use a public restroom door handle, do not wash after, go about the afternoon
8	Sit on public transport in the clothes I will later sit on my bed in
9	Handle money, then prepare food at home without washing

Harm

SUDS	Exposure
3	Write the sentence “I could hurt someone” and read it back once
4	Read the sentence daily without mentally reviewing whether I meant it
5	Chop vegetables with a sharp knife while alone, no checking my reaction
6	Chop vegetables while my partner is in the room
7	Hand my partner a knife, handle first, and do not ask if that was okay
8	Read a news article about a violent crime, no reassurance-seeking after
9	Spend an afternoon alone with my niece without texting anyone about it

Note what the right-hand column has in common: each one names the compulsion being prevented. An exposure item that does not specify the response prevention is only half an item.

Step 4: work the rung, do not admire it

Pick something around 3 or 4 and repeat it, often daily, until it is uninteresting. Two things to track each time: what you expected to happen, and what actually happened. Under the inhibitory learning model, that gap - the expectancy violation - is what drives the change, more than watching a number come down.

A rung is done when the surprise has gone out of it. Then move up.

Five common mistakes

Building the hierarchy as a compulsion. Endlessly perfecting the list, re-rating items, reordering. The list is scaffolding. Get it good enough and start climbing.
Leaving out response prevention. The most common failure by a distance. An exposure you followed with the ritual has taught the ritual.
Starting at the top. Bravery is not the mechanism. Repetition is.
Missing the mental compulsions. Silently reassuring yourself mid-exposure, mentally reviewing afterwards, praying, counting. These are compulsions and they cancel the exposure. See Pure O.
Treating it as fixed. A hierarchy is a living document. New triggers appear; old ones stop mattering. Expect to revise it.

What this looks like from the inside

My first hierarchy was too polite. I wrote items I already half-believed were fine, because building an honest list meant writing down what I was actually afraid of, in words, where I could see it. That took a second attempt and a fair amount of shame.

The other thing I got wrong was pacing. I wanted to leap from 4 to 8 because the middle rungs felt like a waste of time - like admitting I was not brave enough. I failed the 8, felt terrible, and lost about three weeks. The middle rungs are not a concession. They are the treatment.

The version that finally worked was almost embarrassingly incremental, and it was the one that got me through.

Sources

International OCD Foundation: Exposure and Response Prevention
Abramowitz, J. S. (2006). Understanding and treating obsessive-compulsive disorder: A cognitive behavioral approach. Routledge.
Craske, M. G., et al. (2014). Maximizing exposure therapy: An inhibitory learning approach. Behaviour Research and Therapy, 58, 10-23.
Wolpe, J. (1969). The Practice of Behavior Therapy. Pergamon Press - origin of the subjective units of distress scale.