An Introduction to Sensory Processing Differences in Children with Neurodiversity

November 4, 2022 Kathryn Soraya Khamsi

Looking at the mossy insoles of these Japanese geta sandals, you likely had a sensory reaction. You may have relished the thought of slipping your feet into these shoes. Or, perhaps, it was a horrifying thought, and you instinctively recoiled and grimaced. Why do we have these different reactions? It is due to our subtle sensory processing differences.

What Is Sensory Processing

Sensory processing is how our bodies detect, interpret, and interact with the physical world immediately around us. This is a complex neurological process where the body’s central nervous system receives physical signals, registers and interprets these signals as stimuli, and reacts accordingly. Put differently, what is physical becomes mental/neurological and then physical again through a visceral motor response. This feedback loop shapes the brain and influences our psychological state. Subconsciously, we are simultaneously processing a lot of physical information — visual, auditory, tactile, olfactory, gustatory, vestibular, and proprioceptive — and our central nervous system must organize it.

What are referred to as “sensory issues” or “sensory processing differences” at Prism Advocacy are often diagnosed by clinicians as Sensory Processing Disorders (SPD). Sensory Processing Disorders are a unifying thread among individuals with neurodiversity. It is associated with conditions of ADD/ADHD, Autism Spectrum Disorders, Auditory Processing Disorders, Visual Processing Disorders, Obsessive-Compulsive Disorders, Tourettes, Giftedness, and Anxiety. In these instances, an individual’s sensory processing system(s) may not efficiently organize sensory signals, causing an imbalance within the central nervous system that can significantly impact everyday life and result in chronic overstimulation, sensitivity, or dysregulation.

The autonomic nervous system regulates sensory information through the sympathetic and parasympathetic branches. This is the involuntary part of our central nervous system, meaning we are not in conscious control of it. When there is a significant imbalance, the sympathetic nervous system may revert to a fight-flight-freeze response. An individual may struggle to access the parasympathetic nervous system that relaxes the body for higher-level thinking and problem solving.

Sensory Overload

Now, remember those mossy shoes? What if I presented you with a whole wardrobe of mossy-lined clothing: tops, bottoms, socks, hats, and gloves, all lined with moss? When would it be too much? It’s hard to say, right?! You don’t know until it just is. Imagine how hard it is for a child with SPD to calmly navigate the world when sensory stimuli are hard to organize, and, suddenly, it’s just too much. What if your nervous system interpreted moss's soft, fuzzy touch as pain?

When the autonomic nervous system is imbalanced or disorganized, it is like a sink with a slow drain and leaky faucet; eventually, water will overflow. That is when we feel dysregulated, and when we do, we find ways to cope, some helpful and others maladapted. Sensory Processing Disorders children are precisely the same. They find ways to cope, and there are patterns of behavior associated with certain aspects of SPD.

Pediatric Occupational Therapists (OTs or OTR/L) help detect these imbalances and aim to better “integrate” or “organize” sensory systems through therapy. We can probably all think of a soothing sensory experience (e.g., a favorite piece of music) and a sensory intolerance (e.g., touching slimy slugs). Pediatric Occupational Therapists work with these to develop a sensory diet. This individualized plan offers a child sensory activities on a schedule or in a predictable way to assist with their attention, state of arousal, and adaptive responses.

Sensory System Overview and Behavioral Patterns

The following briefly introduces some of these sensory systems and a few behavioral patterns associated with SPD in children.

The Auditory System (sound) converts sound waves into neural signals. This system includes the peripheral auditory system (e.g., ear physiology and mechanics) and the central auditory system (e.g., attending, analyzing, processing, and integrating sounds into words, ideas, and thoughts). When an auditory processing difference is present, the ears and brain are not efficiently coordinating with one another, so a child may:

be easily startled by unexpected sounds,
have difficulty focusing or responding to speech in busy or echoey environments,
take longer to respond in oral communication,
get easily distracted and anxious in social situations,
misunderstand sarcasm or jokes or appear amusical, and/or
suffer from unusual separation anxiety when separated from a particular family member or friend who they depend on to help guide them when they are auditorily lost.

The Visual System (sight) detects light through our eyes for our brain to interpret depth, color, distance, orientation, and motion. Good vision is more than visual acuity (or 20/20 eyesight). Children with ADHD are three times more likely to have ocular-motor or visual processing challenges. A child with SPD in this area may demonstrate the following:

an unusual sensitivity to light,
difficulty sustaining eye contact,
difficulty keeping place while reading, and/or
difficulty with visually stimulating activities like word searches, puzzles, and visually busy seek-and-find books.

The Olfactory System (smell) is directly linked to our emotions, memory, and taste and plays a protective role. A child with SPD in this area may:

have an unusual overreaction or sensitivity to smells,
under-react to unpleasant smells, and/or
have picky eating habits.

The Gustatory System (taste) reacts to chemical stimuli and is directly linked to emotions and memories. A child with SPD in this area may:

be highly anxious when trying a new food,
avoid foods with certain textures and temperatures, and/or
crave intense flavors and extreme temperatures of food.

The Somatosensory System (felt sense) is a general sense associated with specialized receptors throughout the body in the skin, muscles, tendons, joints, ligaments, and in the walls of visceral organs (i.e., abdomen and pelvic areas). For example, our sense of touch or tactile system comes from mechanoreceptors and thermoreceptors in our skin. These receptors have the following function, and a child with SPD in this area may behave accordingly:

Mechanoreception relates vibration, pressure, and discriminatory touches like itches, tickles, and light touches on the skin, so a child may rub or avoid light touches or not even notice. Bathtime face and hair washing are a continuous struggle.
Thermoreception relates to temperature, so a child may fail to notice when they are running too hot or too cold, or their choice of clothing may mismatch the weather.
Nociception relates to pain, so a child may appear to overreact to minor injuries or underreact, failing to notice when injured.
Vestibular (or equilibrioception) relates to balance. The vestibular system is a powerful integrator that interacts with all other sensory systems, impacting our posture, balance, muscle tone, and bilateral coordination. So a child may be unusually clumsy and fall, trip, or bump into things. They may resist tipping their head back, as being flipped upside-down is distressing. Others suffer from motion sickness or fail to get dizzy.
Proprioception relates to positioning and movement, so a child may rely primarily on their vision more than their felt sense (e.g., looking into a bag because they struggle to find something with only their hand in it, or fingered gloves are hard to put on even after lots of practice; be scared of the dark and not move unless they can see their body).

Note that the special senses and proprioception mitigate external sensory stimuli, or exteroception, while the remaining somatosensory systems are internally sensing or interoception. The vestibular system is integrated in a way that does both through equilibrioception, which guides how the body orients itself with gravity affecting balance and movement.

Additional Sensory Subdivisions: Modulation, Discrimination, and Motor

Sensory processing is further broken down into the following subdivisions:

Sensory modulation refers to the complex processing of neural messages that convey information about the intensity, frequency, duration, and novelty of sensory stimuli to the brain. Individuals may be under-responsive, over-responsive, or craving/seeking sensory stimuli, as well as a combination depending on the sensory system.

Under-responsive individuals have difficulties detecting and responding to sensory input.
Over-responsive individuals are avoiders and may easily get overwhelmed by stimuli, becoming withdrawn, defensive, or anxious.
Seekers/Cravers actively seek additional stimuli but may become more dysregulated as they exhibit low impulse control and constant moving, fidgeting, bumping into things, or fiddling with objects. This is common in ADHD.

Sensory discrimination refers to processing all the sensory information from the systems mentioned above, and a child with problems in this area may:

have difficulty registering and interpreting sensory information (e.g., doesn’t notice they’re hurt),
be unaware of the pressure or force they’re exerting at a given moment (e.g., habitual crayon breakers), and/or
be prone to spilling drinks or breaking toys.

Sensory motor refers to differences in processing sensory information that result in disorganized motor output, or dyspraxia, where it can be difficult to perform both novel and habituated tasks. Postural differences can also be a part of this profile. A child may:

have poor hand-eye coordination,
take longer to learn a new task in comparison to the efficiency of their peers
have trouble with concentration and/or
have poor core strength, slouchy posture, and tend to prop up their body against others or lean on furniture for support.

In a previous post, I emphasized that while these sensory systems are studied discreetly, they work in an integrated way and not in isolation. For example, the vestibular, somatosensory, and visual systems work together for postural control and to achieve balance. Vestibular receptors within the inner ear respond to gravity and detect motion or changes in head position. This feedback helps us know whether our bodies are moving or at rest, our body’s speed and direction of movement.

Incoordination and Neurological Overflow

Bilateral coordination is using both sides of the body and is a critical developmental skill, and there are three different types:

Symmetrical or synchronized movements require both sides of the body to work in tandem, like clapping or rolling out dough.
Reciprocal or alternating movements are when one side of the body completes an action that is then repeated on the other side of the body. This includes crawling, walking, running, skipping, and swimming.
Leading/Supporting actions require both sides to complete the movement. Handwriting is an example: you need one hand to write, but the other must simultaneously hold down and stabilize the paper.

Bilateral coordination difficulties can make seemingly simple tasks very frustrating, so, often, these children are great avoiders. A critical part of lateralization is the midline, or an invisible felt line down the center of the body that divides the body neurologically into left and right. Crossing the midline is an integral part of efficient movement and coordination. Issues with crossing the midline may show in a variety of ways. For example, a child’s eyes may struggle to coordinate fluid tracking; some children may appear ambidextrous or have either one very dominant hand or no dominant hand reaching for a utensil with whichever hand is closest, and it can even impact speech articulation if a tongue has trouble moving from left to right.

As mentioned above, some children experience sensory overload, where their system is flooded with too much sensory information at once, and they cannot process multiple sensory stimuli (e.g., trouble listening while visually attending). Or, they may experience neurological motor overflow when the level of attention required to perform a task is accompanied by extraneous, unintended motor movements. An example many of us can relate to is when you are trying to concentrate intensely, and perhaps you stick your tongue out while focusing on getting a tricky job done. Children with neurological processing differences may experience motor overflow more often than their peers and with greater intensity.

What To Do If This Rings A Bell

This is just a brief overview of sensory systems and processing, clearly a complex area of specialization. Consider a pediatric occupational therapy evaluation for your child if these SPD-related behavioral patterns ring a bell. A clinical evaluation with a Pediatric Neuropsychologist or Developmental-Behavioral Pediatrician may also be of benefit, as sensory issues often coexist alongside other conditions. Larger pediatric clinics and hospitals may have specialized behavioral health units with resources.

Additional Resources

Books

The Out-of-Sync Child by Carol Kranowitz and Lucy Jane Miller

The Out-of-Sync Child Has Fun by Carol Kranowitz

Brain-Body Parenting: How to Stop Managing Behavior and Start Raising Joyful, Resilient Kids by Mona Delahooke

Hey Warrior by Karen Young

Raising a Sensory Smart Child: The Definitive Handbook for Helping Your Child with Sensory Processing Issues by Lindsey Biel

The Self-Driven Child: The Science and Sense of Giving Your Kids More Control Over Their Lives by Ned Johnson & William Stixrud

Beyond Behaviors: Using Science and Compassion to Understand and SolveChildren’s Behavioral Challenges by Mona Delahooke

What to Do When You Worry Too Much: A Kid’s Guide to Overcoming Anxiety (What to Do Guides for Kids) by Dawn Huebner

Helping Your Anxious Child: A Step-by-Step Guide for Parents by Ronald Rapee et al.

Make Your Worrier a Warrior: A Guide to Conquering Your Child’s Fears by Dr. Dan Peters