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Sensory Processing, Part 4: Exposure Therapy

As I've said before, sensory needs are often the driving force behind a lot of children’s behavior issues, starting very early in life. In particular, sensory avoidant behaviors can limit activities and cause families a lot of stress. When our kids struggle, we want to find solutions to their problems. And in the realm of sensory sensitivity, exposure therapy is one option that's often presented to parents.

An Evidence-Based Rose By Any Other Name

Whether it's called exposure therapy, desensitization, or sensory integration therapy, the idea is the same. A person will be sequentially exposed to their trigger in ever-increasing doses until the aversion is resolved. Gradual exposure trains the central nervous system to perceive the trigger as a normal part of life, not a threat. Or at least that's what's supposed to happen.

Understanding Threshold

To understand how this works, you have to understand the concept of exposure threshold. In this situation, the threshold is the point that must be exceeded to elicit the anxiety response. In other words, a person's threshold is an imaginary line drawn to separate reactivity and non-reactivity. So before you cross that imaginary line, you are "sub-threshold", and beyond that line, you are "over the threshold".

For desensitization to work well, you need to stay sub-threshold, in an area where you can acknowledge the stimulus but not cause any major emotional effect. Exposure at this level can train the brain to turn down its anxiety response to certain stimuli. Going over the threshold can cause hypersensitization due to triggering a severe anxiety response. That severe response leads to emotional trauma and potentially to Post-Traumatic Stress Disorder. So desensitization is a balancing act. "Expose but don't over-expose" is the mantra of exposure therapy.

It's also important to note that desensitization was originally intended to address anxiety and the fight-or-flight response that occurs during exposure to a trigger. The effect on sensory hypersensitivity is less clear. Some people report a great response to therapy. Others report simply learning to ignore the pain and push through it, which has significant long-term health effects. So exposure therapy may be helpful for the anxiety associated with hypersensitivity but may not be as effective in addressing the actual pain and discomfort of the exposure. Still, it may be worth a try, as long as it's done safely. And that's the tricky part.

Candidate Criteria

For exposure therapy to be done safely, your child must meet 3 criteria:

  1. Your child must consent freely. (Note: Technically, the term is assent, but that's probably splitting hairs and is a conversation for another day.)

  2. Your child must be able to recognize their symptoms of anxiety as they occur.

  3. Your child must be able to communicate those symptoms and feelings of anxiety in general while under stress.


To consent, a child needs to be able to demonstrate a full understanding of what they're agreeing to do. In this case, a child must understand that they are going to be exposed to the very stimulus that causes them so much anxiety over and over again until they get used to this. And they have to agree freely to this process.

This is where things get tricky. Freely consenting requires that no pressure be present. So, no Mama standing over them while the process is explained, no nice therapist staring at them while they think about it, no ingrained desire to please adults, and no previously internalized social pressure to be "normal." If any of that is present, consent cannot be freely given.

Also, consent is fully revokable. At any time and for any reason, a child has the right to change their mind and decline the therapy.

As medical professionals, we aren't accustomed to gaining consent from children. Our rather patriarchal system assumes that parents know what is best for their children and can consent on their behalf. But for something that has the potential to do lasting psychological harm to a child, that child absolutely needs to buy into the process and be willing to take that risk. We cannot conflate parental consent and child consent here. To do so is a violation of basic human rights.

Identifying Anxiety

In the case of exposure therapy, the ability to sense and identify their own symptoms of rising anxiety is essential for maintaining a child's safety. Remember, sub-threshold exposure can desensitize, but exposure over threshold will absolutely create more sensitivity and fear. So staying subthreshold is critical.

The only way to guarantee that a child stays sub-threshold is for the child to tell us they are sub-threshold. And to tell us that, the child must first be able to identify the feelings and sensations that indicate that they are approaching their threshold. That's really a function of their interoception skills. For children with sensory processing differences, interoception may be impaired.

This is also about recognizing one's own emotions. In populations with a high likelihood of co-occurring alexithymia (*cough* autistic people), recognition of emotions can be impaired. If both interoception and recognition of emotions are not fully intact, there is no conceivable way of assuring that exposures remain sub-threshold.

Communicating Proximity to Threshold

Even if a child can sense their approaching threshold, they must be able to communicate that feeling reliably under stress. Exposure therapy is stressful. In fact, if it's not a little stressful, it's probably not going to work. The whole point is to create some small level of stress and tolerate it in order to decrease later sensitivity. And all of that is totally fine. But if the child can't communicate when they're close to their threshold of tolerance, the risk of going over threshold is incredibly high and the risk of harm is also incredibly high.

"Under stress" are keywords here. A child may be able to say words like "stop," "too much," or even "no" at various times. But communicating the need to stop the exposure in the moment may be a very different thing. Both situation mutism and autistic verbal shutdown may occur under exposure stress, and either of these will impair communication at critical points in exposure therapy. Because the inability to communicate at key points can lead to over-exposure and result in emotional trauma, any kind of exposure therapy in those with communication barriers is not an option.

Still an Evidence-Based Rose

Exposure therapy has reclaimed many lives from anxiety disorders like phobias, for which the evidence is strongest. It's a phenomenal tool when used properly. So is a hammer. But use a hammer wrong and immense damage can result. So before you embark down a desensitization pathway, be sure that it's safe. The damage it can do can't be easily undone. And it's not worth that pain.

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