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Sensory Processing Disorder. A neurological traffic jam.














Sensory Processing Disorder (SPD) is a neurologically-based condition that exists when the nervous system fails to properly receive and organize messages from the senses. This leads to inappropriate motor and behavioral responses, and causes confusion, distress, and discomfort. It is a physical, neurological condition that can have psychological ramifications in adulthood. In the words of Dr. A. Jean Ayres, neuroscientist, occupational therapist, and pioneer in the field of SPD, “When the flow of sensations is disorganized, life can be like a rush hour traffic jam.”


There are three primary subtypes of SPD, and these subtypes can be broken down into further subtypes:


1. Sensory Modulation Disorder (SMD)

​     a) Sensory Craving: seeks sensory input

     b) Sensory Over-Responsivity: avoids sensory input

     c) Sensory Under-Responsivity: ignores sensory input


What's it like to have SPD - SMD? It depends on the person's individual experiences and specific subtype.

For example, the sight of light may be perceived as painful, problematic, and supremely bright for those who

are over-responsive. A person who is sensory-craving might actively seek light and turn on every lamp in the house.

Someone who is under-responsive might not even notice light and leave lamps on, even as they sleep.

This may hold true for every sense or just for some senses: a person with SPD may crave touch but avoid movement

and not even notice smell. Each case is a unique assortment of sensory sensitivities, but they all add up to SPD.


2. Sensory-Based Motor Disorder (SBMD)

    a) Dyspraxia/Motor Planning: trouble carrying out new motor actions

    b) Postural Control Disorders: trouble stabilizing body/posture


SPD - SBMD is a difficulty with the way the physical body interacts with the physical environment. Those with dyspraxia or poor motor planning might have difficulty coordinating a sequence of actions with an end goal, such as buttoning a shirt, as well as poor hand-eye coordination. These are sensory-based actions often involving multple senses at once - particularly sight, touch, and proprioception. Those with postural control disorders typically have poor eating skills, difficulty with depth perception, and frequently struggle to maintain balance. 


3. Sensory Discrimination Disorder (SDD): trouble understanding the basic qualities of people, places, objects, or the environment.


People with SPD-SDD have a tough time interpreting sensory information. For example, they may not be able to distinguish between flavors, the source of odors, or between shapes and colors. 


For more information on SPD, related symptoms, and checklists, visit the STAR Institute for SPD.

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