What is Exposure and Response Prevention (ERP)?

Exposure and Response Prevention (ERP) is an evidence-based treatment for obsessive-compulsive disorder (OCD) and other anxiety disorders. There are various ways to utilize ERP. However, the basis of all ERP methods involves exposure to anxiety-inducing situations.

People with OCD experience intrusive or obsessive thoughts, which cause distress and lead them to engage in some form of compulsion to relieve this anxiety. OCD can look very different depending on the person. Some common obsessions include fears over contamination, fears over the possibility of harming oneself or others, excessive worry over violating religious or general morals, etc. If a person cannot perform a compulsion, they typically feel extreme levels of distress. Some common OCD compulsions include cleaning or washing, checking, or reassurance seeking. People with OCD also avoid situations that might bring on their obsessions.

ERP can also be used as a treatment for people with anxiety disorders. With anxiety disorders, individuals typically engage in some avoidance behavior to lessen their anxiety. It includes specific phobias; for example, if a person has claustrophobia, they fear possibly being trapped in a small space. Because of this, they may avoid elevators, public transportation, or events that will be very crowded. With panic disorder, individuals who have had a panic attack in the past fear the possibility of having another one. It results in them avoiding any potential situation in which they think a panic attack might occur. With social anxiety disorder, individuals often avoid social situations in which they may feel anxious.

The compulsions or avoidance behaviors people with OCD and other anxiety disorders engage in may work to lower their distress for a brief time; however, in the long term, they only increase an individual’s anxiety about the feared situation. These behaviors only end up reinforcing the idea that these feared situations are worthy of the amount of distress they are causing because if an individual never allows themself to experience the feared stimuli, then they never get to learn that it may not be as scary as they are making it out to be. ERP works by exposing the individual to the feared stimuli and having them experience the anxiety and distress that comes with it while resisting urges to avoid or engage in compulsions. ERP involves inhibitory learning, which involves pathways of learning in our brains. Before starting ERP, an individual may only have a fear pathway that associates the feared stimuli with distress, leading to compulsions or avoidance (Coyne, 2020). When engaging in ERP, our brains begin to learn that the previously feared stimuli are no longer distressing, and over time as this newly learned pathway repeats, it begins to inhibit the old pathway of fear and anxiety (Coyne, 2020).

A key component of ERP is habituation, a process in which the central nervous system becomes comfortable with stimuli through repeated and prolonged interaction or exposure. An example of this could be when you go into a hot tub. At first, the water usually feels extremely hot, and it might take time to get fully into it. However, after a few minutes, your central nervous system becomes used to the temperature, and the water no longer feels as hot as it did when you first got in. In ERP, this habituation process helps individuals get used to the feared stimuli or situations- this is the “exposure” part of ERP. Response prevention involves voluntarily preventing compulsions or avoidance behaviors. It relates to the other key component of ERP called extinction. Extinction is the “gradual weakening of a conditioned response that results in a behavior decreasing or disappearing.” Compulsions and avoidance behaviors are the conditioned responses that only serve to worsen anxiety and obsessions in the long term. By voluntarily blocking these responses, the hope is that the obsessions and anxiety will lessen over time. An example of this would be a child who has learned that if they tantrum in a store, their parent will eventually give them the toy they want to quiet them down- if the parent stops giving in, the tantrums may worsen for a bit at first. However, over time the behavior would become extinguished as the child learns that tantrums will no longer get them what they want.

ERP often sounds daunting to individuals because it forces them to sit with and confront their anxiety and distress rather than immediately trying to get rid of it through compulsion or avoidance. However, the more people experience anxiety in these feared situations, the easier it becomes. The end goal of ERP is complete habituation to the feared situation and complete cessation of all compulsions and avoidance responses. However, ERP is a process done in steps, with many ways to apply it.

Components of ERP:

Subjective Units of Distress Scale (SUDS):

ERP utilizes the Subjective Units of Distress Scale or SUDS (Wolpe, 1969), a self-reporting scale to rate how much distress a person feels at a given moment. The scale goes from 0-100, with 0 meaning no anxiety or distress present and 100 being the most anxiety or distress the person has ever experienced. ERP asks the individual to rate their SUDS level throughout exposure exercises to recognize how distress levels change with treatment over time.


Exposure Hierarchy:

In ERP, individuals create and utilize exposure hierarchies to guide them through the process. SUDS are utilized with the exposure hierarchy. The exposure hierarchy lists 10-15 feared situations related to the individual’s main obsession or anxiety trigger. For each item on the hierarchy, they will also rate the SUDS level they feel the situation would produce if they could not avoid or engage in a compulsion. The items should be organized from lowest to highest SUDS level to work up over time. Additional exposure hierarchies or mini-hierarchies can be created for each item in the primary exposure hierarchy if needed.

Below is an example of an exposure hierarchy for Sam, who has contamination-related OCD and fears becoming infected with an incurable illness. Sam tries to avoid situations where he believes he may be exposed to blood or germs and engages in hand-washing compulsions and cleaning rituals that take up hours of his day. He tries to avoid public transportation and other busy public areas where he believes he could become contaminated and fears letting anything that leaves the house touch “clean” objects inside his house.


Situation and SUDS Level:                                                                                                                     

Putting a backpack that was on the subway floor on top of a bed comforter (100)

Partner holding my hand before washing it after getting off the subway (90)

Touching the railing in a crowded subway (80)

Putting a coat on the couch after just wearing it outside (70)

Putting cell phone on the bed after being out all day without cleaning/wiping down (60)

Using and touching an ATM (45)

Touching the buttons on a busy elevator (35)

Going on a subway with less than five other people on it and not touching anything (20)

In Vivo” Exposure:

 “In vivo” exposure means prolonged exposure in a real-life setting. The above situation would be done “in vivo.” The first step would be choosing a situation off of the list that results in a mild to moderate SUDS level. If Sam chose to start with the scenario “putting cell phone on the bed after being out all day without cleaning/wiping down” example, he would most likely utilize a mini hierarchy to help him work up to this in steps. He may start by touching his uncleaned phone and then placing his unwashed hand on his bed and preventing himself from engaging in the compulsion to wash the sheets or bedding. The anxiety will rise at first but will eventually begin to decrease. Sam will wait until the SUDS level decreases by about half, which is a sign that habituation is happening. This exercise should be repeated on consecutive days until the SUDS level reduces to about 20. When this occurs, Sam could move up to the next item on his exposure hierarchy and repeat until he eventually can put his uncleaned phone on his bed without engaging in any compulsions. At that point, he would then move to the following situation on his main exposure hierarchy.


“Imaginal” Exposure:

 It is not always possible to carry out exposure in real life; in this case, it can be helpful to utilize imaginal exposure. With imaginal exposure, the individual purposely thinks about distressing and uncomfortable thoughts, keeping them in their mind until they become habituated and cause less distress. The process of imaginal exposure involves writing out a narrative in the first person describing a distressing obsession and what would happen if they did not engage in their compulsion or avoidance behavior. The narrative would include the thoughts, physiological reactions, fears, and worst-case scenarios related to the situation (Hyman & Petrick, 2010). Suppose this is used with someone with social anxiety disorder who fears public speaking. In that case, they may use this to imagine what it would be like to give a speech to a room full of people, imagine the feelings and thoughts they might be having, and what it would be like if the “worst-case scenario” happened such as forgetting their speech or embarrassing themselves. The individual would then record themself saying their narrative and start with listening to it for about 45 minutes straight over and over every day, tracking their SUDS level until it gets to 20 or lower. Once it gets to that level, then they can move on to other feared thoughts or situations. Doing this over time lessens the impact of the thoughts on the person and teaches them that their thoughts are just thoughts and not facts.

ERP can be a very effective treatment, and there are many different ways of applying ERP depending on the type of symptoms an individual struggles with. This type of treatment requires specific tailoring to the individual to address their symptoms directly. While it can seem overwhelming at first to directly face the source of your distress, the result of finally taking back control of your symptoms is very freeing and allows individuals to go back to living their life on their terms.


Coyne, L. (2020). The New Exposure Therapy: How Inhibitory Learning Can Improve Outcomes for OCD and Anxiety Disorder. [PESI].

Hyman, B. M., & Pedrick, C. (2010). The OCD workbook: Your guide to breaking free from obsessive-compulsive disorder.

Wolpe, J. (1969). Subjective Units of Distress Scale (SUDS) [Database record].

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