Exposure is About Learning, Not Habituation

When I was first trained in exposure therapy, I was taught that exposure works because the patient habituates (gets used) to the stimulus that causes them anxiety, or habituates to the feeling of anxiety itself.  On paper, this makes a lot of sense. Here’s how I used to explain it to patients:

“If a person is scared of dogs, and they cross the street every time they see a dog and avoid any place where they might run into a dog, that person will never get used to dogs, and so their fear will never go away.  But if that person chooses to be around dogs despite their fear, they will eventually get used to being around dogs and no longer be afraid. In other words, they will habituate to dogs.”

I would then apply this concept to whatever it was that the patient was afraid of:

“If you avoid talking to new people, you’ll never habituate to it”; “If you avoid things that trigger uncertainty about getting sick, you’ll never habituate to that uncertainty.”

This all sounded very logical.

But the more patients I saw, the more I was convinced that habituation wasn’t actually what made people get better, and that thinking about exposure through this lens could sometimes backfire.  I started thinking that exposure actually worked because it gives the patient the chance to learn (1) that what they expect to happen doesn’t happen, and (2) that they have the ability to handle their thoughts and emotions in a different way and that this changes how they feel.

An example of the former is learning that playing with a dog usually doesn’t end in the dog biting you.  An example of the latter is learning that you can choose not to ruminate in response to a trigger, or choose to do something despite being anxious about it, and that both lead to feeling less anxious.  I believe that this latter type of learning is actually the most important factor in making exposure therapy work.  From this perspective, the problem with avoidance and compulsion isn’t that they prevent habituation, but rather that they eliminate opportunities for these different types of learning.

Around the same time as I was beginning to think this way, I learned about some new research on ‘inhibitory learning’ that was pointing in the same direction.  This research suggested that exposure works because it provides opportunities for learning experiences that disconfirm a person’s negative expectations (e.g., Jacoby and Abramowitz, 2016), like the first type of learning discussed above.

During this same period, I also had the privilege to complete advanced training with Dr. Elna Yadin, one of the world’s experts on exposure therapy for OCD and PTSD.  Dr. Yadin put it best: “Earthworms habituate. People learn.” According to her, the idea that exposure therapy is based on learning is not a new idea at all.

But does it really matter why exposure works?  Isn’t the distinction between habituation and learning just academic and theoretical?  No, in fact there are many practical implications to this distinction. Here are some implications of looking at exposure from the perspective of learning, as opposed to desensitization:

  1. The goal of an exposure is not to make you anxious, and it’s okay if it doesn’t.  If you are giving yourself the opportunity to learn something new by doing something you’ve previously avoided, or by doing something without an accompanying compulsion, that’s a good exposure.
  1. An exposure that makes you anxious but doesn’t involve any new learning is a waste of time.  A huge amount of time and energy (and money) is wasted on exposures like this.
  1. There is no reason to “stay with the anxiety,” and in fact it’s better not to.  I want my patients to learn that they can move on after something triggers anxiety.  In my experience, when people “stay with the anxiety” they often end up ruminating and making themselves more anxious, with no added benefit.
  1. There is nothing wrong with using ‘coping skills’ to calm yourself down when you’re anxious, as long as the coping skill isn’t functioning as a compulsion.  Some people who think that exposure works because you habituate to the anxiety discourage patients from doing anything to lessen their anxiety. I strongly disagree with this.  In fact, I encourage the use of ‘coping skills’ as a way to get through an episode of acute anxiety without resorting to a compulsion. The exception to this would be a case where the person is afraid of the anxiety itself (e.g., “If I get too anxious I’ll lose control/never stop feeling anxious/etc.”).
  1. ‘Imaginal exposure’ is only helpful if it provides an opportunity for learning.  (For an in-depth discussion, see Using Imaginal Exposure When Practicing ERP from a Learning Perspective.)

To illustrate the above distinctions, consider the example of an exposure for emetophobia (fear of vomiting):

Here is what an exposure for emetophobia might look like when the goal is learning:

Eat an avoided food and then move on with your day.  Don’t ruminate about it or monitor your body for signs of nausea.  Give yourself the chance to learn that you don’t actually vomit and that if you stop ruminating and checking, the fear resolves pretty quickly on its own.  If you have trouble moving on, by all means do something to calm yourself down or get distracted, as long as whatever you’re doing isn’t aimed at preventing vomiting.

Here is what an exposure for emetophobia might look like when the goal is habituation:

Eat an avoided food and then sit there and imagine yourself vomiting over and over.  Habituate to the possibility of vomiting.

As you can see, there are significant practical differences between these two approaches.  In my experience, approaching exposure therapy from the perspective of learning makes the treatment faster, more effective, and much less unpleasant for the patient.

References

Jacoby, R. J., & Abramowitz, J. S. (2016). Inhibitory learning approaches to exposure therapy: A critical review and translation to obsessive-compulsive disorder. Clinical Psychology Review, 49, 28-40.