What is Sensory Processing Disorder?

For the longest time, we were taught that there were 5 senses; vision, hearing, touch, smell, and taste. In more recent years, research has identified and added proprioception, vestibular, and interoception senses to that list. Proprioception refers to the body’s awareness of its own position, orientation, or location in space. The vestibular sense further supports movement as it is responsible for perceiving gravity and balance. Interoception however is defined as the ability to recognize and interpret one’s own internal bodily cues and functions such as pain, thirst, hunger, and exhaustion.[1]

Interestingly, no two people experience or interpret these sensory processes the same. Sensory Processing Disorder  is a condition that affects how one’s brain processes sensory information coming from the 8 senses. Sensory Processing Disorder  is typically understood by 3 broad patterns of symptoms and experiences: Sensory Modulation Disorder (SMD), Sensory-Based Motor Disorder (SBMD), and Sensory Discrimination Disorder (SDD).

The Sensory Modulation Disorder (SMD) pattern encompasses the sensory over-responsivity, sensory under-responsivity, and sensory-craving subtypes. individuals with modulation differences, characterized by over-responsivity, tend to feel bigger or exaggerated reactions toward incoming stimuli, resulting in a desire to avoid certain sensory situations. On the other side of the spectrum, under-responsive individuals have difficulty detecting or responding to sensory input altogether. The sensory-craving subtype, which often accompanies the sensory under-responsivity subtype, is frequently misinterpreted as hyperactivity associated with an attention-deficit disorder due to a tendency to constantly seek sensory stimulation.

The Sensory-Based Motor Disorder (SBMD) pattern includes postural disorder and dyspraxia. Postural disorder is related to one’s inability to activate or stabilize the muscles in his/her body during movement or at rest. Dyspraxia however is associated with motor planning difficulties, which are said to result from the body’s inability to react and respond to sensory stimulation and communicate this information to the brain. While this is often called a Developmental Coordination Disorder by psychologists, it is often referred to as Dyspraxia by occupational therapists.[2] It is important to note that this is not the only disorder in which different names are given by various disciplines. 

Lastly, Sensory Discrimination Disorder (SDD) pattern is characterized by an inability to recognize and interpret sensory information. This can manifest as difficulty understanding or discriminating between things that are seen, heard, felt, tasted, or smelled. For example: “Do I see a “P” or a “Q”? Do I hear “cat” or “cap”? Do I feel a quarter or a dime in my pocket? Am I falling to the side or backwards?”[3]

While psychologists and neuropsychologists can assist with the identification and diagnosis of such differences, most therapies are conducted by occupational and physical therapists. The most common type is Sensory Integration Therapy which incorporates the use of “sensory-rich, child directed activities to improve a child’s adaptive responses to sensory experiences.[4]” Interventions that can be easily incorporated into a daily routine at home or in school include things like pressure vests, weighted blankets, sitting on a ball, etc.[5] With the appropriate services and accommodations in place, one’s sensory differences can gradually become less distressing.

Sources and links:

[1] https://sensoryhealth.org/basic/your-8-senses

[2] Diagnostic and Statistical Manual of Mental Disorders: DSM-5. American Psychiatric Association, 2017.

[3] https://sensoryhealth.org/basic/your-8-senses

[4] Case-Smith, J., Weaver, L. L., & Fristad, M. A. (2015). A systematic review of sensory processing interventions for children with autism spectrum disorders. Autism, 19(2), 133-148.

[5] Case-Smith, J., Weaver, L. L., & Fristad, M. A. (2015). A systematic review of sensory processing interventions for children with autism spectrum disorders. Autism, 19(2), 133-148.