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The Ultimate Guide to Sensory Processing Disorder

By Alescia Ford-Lanza MS OTR/L, ATP | Written on July 11th, 2021

While Sensory Processing Disorder isn't as known as other Autism Spectrum Disorder (ASD) or Attention-Deficit/Hyperactivity Disorder (ADHD), it potentially is a more widespread challenge for children in today's enviroment.

Up to 16% of school-aged children may have Sensory Processing Disorder. 

In this article, we'll cover what you need to know about Sensory Processing Disorder and give you options to dive deeper into certain topics.

Sensory Challenges Assessment

Do you have a kiddo that might have Sensory Challenges? Take our assessment below and we'll send you resources to help out!

What is Sensory Processing Disorder (SPD)?

A textbook definition of SPD is "a diagnosis based on the presence of difficulties in detecting, modulating, interpreting, or organizing sensory stimuli to an extent that these deficits impair daily functioning and participation."

What this means is, when one’s central nervous system has difficulty processing any of this sensory information, the body’s responses are atypical and can be observed in motor, language, or behavioral skill difficulties.

This can show up in life in a variety of ways:

  • Children being sensitive to clothing tags
  • Not liking the feeling of certain fabrics
  • Hating the texture of certain foods
  • Getting overwhelmed by noise or lights

While many of us have "sensory quirks", for most of us, they don't impede our day-to-day lives.

It's once these sensory challenges start to cause issues with our mood, behavior, and sleep is when it starts to become Sensory Processing Disorder.

Occupational therapists are typically the ones who will diagnose these atypicalities as Sensory Processing Disorder or SPD. They will then begin to work on a treatment plan to improve one's ability to process whatever sensory inputs are causing the issues.

3 Subtypes of Sensory Processing Disorder

When we talk about Sensory Processing Disorder (SPD), occupational therapists diagnose 3 subtypes of SPD:

  • Sensory Modulation Disorder
  • Sensory-Based Motor Disorder
  • Sensory Discrimination Disorder

It is likely that people with SPD demonstrate a combination of symptoms from the subtypes, however, a trained Occupational Therapists (OT) will know how to address the different deficit areas in Sensory Integration Therapy.

1) Sensory Modulation Disorder (SMD)

Sensory Modulation Disorder is defined as a difficulty regulating responses to sensory stimuli. The magnitude of these sensory processing difficulties affects key areas of daily functioning and, for many children, it affects their ability to purposefully interact and engage because their arousal level and level of alertness is affected! 

Sensory Modulation Disorder is further split into 3 categories or types based on those atypical responses: Over-Responsive, Under-Responsive, and Craving/Seeking.

We also have a podcast episode on Sensory Modulation Disorder, if you like to listen to your information!


The common name for SMD-SOR is Sensory Defensiveness.

Child has a low threshold for sensory stimuli - meaning, it doesn’t take much for them to be overwhelmed, overstimulated, irritated, or avoidant. 

This child is very sensitive to sensory stimuli. Play, exploration, safety, and comfort are all affected because of this over-responsivity to sensory input. 

Sensory defensiveness is seen in any or all sensory systems. Child avoids or becomes irritated by sensations (fight, fright, flight response). SMD is seen to affect social, emotional, and behavioral areas.

Want To Dive Deeper On Sensory Defensiveness?

We have a deep dive article, which you can see by clicking the button below!


Child has a high threshold for sensory stimuli - meaning, it takes a lot of sensory input to get him to respond as compared to the typical person.

Child does not attend or respond to sensory stimuli in his environment Can appear passive, quiet, or disengaged.

Child may appear clumsy, have difficulty with body awareness, have a high pain tolerance/no pain response, difficulty understanding temperature gradations (hot/cold) Difficulty regulating the force or volume of movements.


The child often looks disorganized as they seek more sensation. 

Child seeks constant stimulation, an intensity of input - jumping, crashing, bouncing, touching, moving, mouthing…however he can get the sensory input he’s seeking! 

This can lead to unsafe, extreme sensory seeking behaviors. Children are typically happiest in busy, stimulating environments.

A child with SMD-SC can be referred to as a "Sensory Seeker".

2) Sensory Discrimination Disorder (SDD)

Close your eyes, put your hand in your pocket or handbag, and feel around for your keys. Did you find them or did you touch upon that old gum wrapper? How do you know what’s what? How do you know how far and in what direction to reach, how to pull your hand out, or what material you were touching?

Better yet, how do you know what is your car key versus your house key without opening your eyes? Now put on a pair of gloves and try again.

Were you as successful in finding what you needed without using a secondary sense of vision? It’s unlikely!

You may not realize it, but every day you use a combination of discrimination senses to help you navigate your world - in this case, you just used your proprioceptive and tactile discrimination senses to help you find what you needed without your eyes!

Sensory Discrimination Disorder can happen in any of the eight sensory systems. 

Here are some characteristics or common observations with SDD:

  • Difficulty interpreting or giving meaning to the specific qualities of sensation
  • Trouble detecting similarities and differences among sensory stimuli
  • Difficulties in daily routines and activities
  • Difficulties with motor planning
  • May be awkward with gross and fine motor skills
  • May appear inattentive to people and objects in their environments

3) Sensory-Based Motor Disorder (SBMD)

Sensory-Based Motor Disorders are manifested by difficulties with balance, motor coordination, and motor tasks. There are two subtypes of SBMD: postural disorder and dyspraxia.


This appears as low muscle tone, decreased balance, decreased motor control; bilateral movements, ocular motor control, oral motor.

The child’s decreased muscle strength affects postural control (sitting, standing with balance) in order to do higher-level skills with control.


Praxia, the root of Dyspraxia, is the skill of motor planning. This skill is how someone makes a plan in their head, then gets their body to execute that move properly.

Dyspraxia is the partial loss of this motor planning ability.

You might also hear the term apraxia, which is the complete loss of Constructional Praxis.

When dealing with dyspraxia, the child appears clumsy or awkward. The child knows the purpose of the task but cannot organize motor actions to solve the motor problem - planning, sequencing, problem-solving. Prefers familiar activities (novel activities require too much motor planning). 

The child can get frustrated easily. Gross motor delays may be more evident than language or fine motor delays.

If you want to learn more about Praxia and Dyspraxia, we have 2 podcast episodes to check out:

The 8 Sensory Systems

How that we've covered the 3 subtypes of Sensory Processing Disorder, it's important to also have an idea about the bodies 8 systems systems!

And, yes, there are 8 sensory systems! Not just 5!

It's important to know all 8 systems since the lesser known ones can have a massive impact when it comes to treating Sensory Processing Disorder

1) The Auditory System

The Auditory System is how our bodies turn sounds in the environment into comprehensible thoughts in our head.

It includes the physical structure of our ears, as well as certain brain regions.

Dive Deeper On The Auditory System

Check out our article on the Auditory System!

2) The Visual System

The visual system is obviously about sight. We all probably have sensory issues with our visual system when it comes to harsh florescent lights that are so prevalent in schools and office buildings.

Dive Deeper On The Visual System

Check out our article on the Visual System!

3) The Olfactory System

The olfactory system is our sense of smell. 

Biologically speaking, our sense of smell has very important functions, including detection of hazards, pheromones, and is involved in our sense of taste, as mentioned earlier.

Dive Deeper On The Olfactory System

Check out our article on the Olfactory System!

4) The Gustatory System

The gustatory system is our sense of taste. The sense of taste is not just one sense that is located in the mouth, but rather several sensations that are experienced in and around the mouth - smell, texture, and temperature. Once the taste is combined with the smell, the actual “flavor” is produced and interpreted by the brain. (article) Just like our sense of smell, our sense of taste is directly linked to memories and emotions.

Dive Deeper On The Gustatory System

Check out our article on the Gustatory System!

5) The Tactile System

The tactile system is our sense of touch, which extends all over our skin! Hands, feet, etc.

Dive Deeper On The Tactile System

Check out our article on the Tactile System!

6) The Vestibular System

The vestibular system may be the first sensory system you haven't heard of on this list!

The vestibular system is the system that deals with change in position, direction, or movement of the head.

Dive Deeper On Vestibular Input

Check out our article & podcast on vestibular input.

7) The Proprioceptive System

Proprioception is the sense that tells your brain where all your body parts are.

It works  even if you’ve got your eyes closed, even when you’re upside down in a handstand, or folded in half cleaning something off the floor.

Dive Deeper On The Proprioceptive System

Check out our article all about proprioception

8) The Interoceptive System

The interoception system is in charge of interpreting our internal information. This means understanding what the feeling of hungry, thirsty, or fatigue actually mean.

While this is unconscious for many of us, some people struggle to connect the feeling to the meaning!

Dive Deeper On The Interoceptive System

Check out our article & podcast all about interoception

What Are The Symptoms Of Sensory Processing Disorder?

The symptoms of sensory processing disorder can generally be classified as sensory seeking or sensory avoidance. 

In addition, some children with SPD have trouble registering input, making them appear aloof or disengaged. We will review each of these categories individually.

Each subcategory has its own symptoms, while there are some overlapping symptoms, like struggling to sleep.

 You can use this symptom list as a guide to determine if your child may have sensory processing difficulties. 

Please be aware that this is by no means a way to diagnose any kind of disorder. This must be done by a trained professional, such as an occupational therapist.

Sensory Seeking Symptoms

Children with sensory seeking symptoms have sensory systems that crave input. In order for them to feel internally settled, they engage in actions that will provide a great deal of input to their systems. 

  • Engages in rough play, such as kicking, rolling, hitting objects, etc. 
  • Hyperactive and have difficulty sitting in one position 
  • Appears to have a lack of body awareness 
  • Chews on objects or clothing 
  • May enjoy spinning in circles
  • Can appear clumsy, might often bump into walls or other people 
  • Enjoys loud music and noises
  • Likes to use hands and wants to constantly touch objects in environment 

Sensory Avoiding Symptoms

Children with sensory avoiding tendencies are oversensitive to certain sensory stimuli within their environment. These stimuli become overwhelming and so they will find ways to avoid it. 

  • May dislike certain clothing fabrics, textures, or tags 
  • Avoids loud music or loud noises  
  • Is bothered by certain textures on hands 
  • Is bothered by certain tastes or food textures 
  • Doesn’t like to engage in movement, may withdraw from physical activities 
  • May exhibit poor fine motor skills (writing, fastening buttons, tying shoelaces, etc)

This symptoms typically fall under the umbrella term of Sensory Overload.

If you'd like to learn more about Sensory Overload and how it can cause anxiety in children, you can learn more here.

Sensory Registration Symptoms

The term registration refers to how a person registers or takes in the stimuli around them. If a child has difficulty with registration, this means they are having difficulty noticing or being aware of the sensory occurrences around them. 

Basically, their brain and body are not processing the number of stimuli from the environment that it should be. 

  • Appears aloof or as if they are unaware of their surroundings 
  • Takes a while to respond to their name or respond to directions
  • May not notice errors in school work
  • Difficulty maintaining correct posture
  • May use excessive force when giving hugs, writing, throwing balls, etc. 
  • Exhibits poor body awareness or appears clumsy 

Think Your Child Might Have Sensory Challenges?

Harkla's in-house Occupational Therapy Assistants have put together a Sensory Challenge Assessment to help parents figure out if looking into sensory integration therapy may be helpful!

Click the button below to take the quick assessment and get recommendations based on your results!

Common Treatments for Sensory Processing Disorder

So what do you do if you suspect that your child may have sensory processing disorder?

First, remember that there is NOTHING wrong with your child! This may just be something that they struggle with and your job is to help them as they grow.

Next, keep reading! We'll cover some common treatments, as well at tips and strategies you can start with right away.

Then, if you are ready to help your child even further, seek out a trained Occupational Therapist in your area who can work 1-on-1 with your child to get them the specific sensory integration therapy they need!

Sensory Integration Therapy

Sensory Integration Therapy is a specific type of therapy that is used by occupational therapists (OTs) to help change how the brain reacts to different sensory inputs.

The different sensory inputs could be any of the 8 sensory systems we discussed above, specific to the child's needs.

These activities are designed to be fun and engaging to make it something the child actively wants to participate in.

Want To Dive Deeper on Sensory Integration Therapy?

We have an article dedicated to Sensory Integration Therapy where you can learn more about it!

Creating Sensory Diets

While it sounds like Sensory Diets are about food, it's actually a term for a specific program of sensory activities that are designed around a child's specific sensory needs.

If you go to an OT to do sensory integration therapy, they'll work with you to create a sensory diet for your child.

However, Sensory Diets, if used properly, can be easily used at home or at school! We do have an article directly related to sensory breaks in the classroom.

We love Sensory Diets so much that we created an entire course that teaches you how to use and modify Sensory Diets for a number of different scenarios. You can click here to learn more about the Sensory Diet Course.

Want To Dive Deeper On Sensory Diets?

We have a deep dive article and podcast all about Sensory Diets!

Bring Sensory Input Home with Sensory Products

At Harkla, we are obviously big fans of sensory products! When used properly, they can provide necessary sensory inputs, improve sleep, and increase focus.

However, we don't believe that families or teachers should buy sensory products without doing research first into which products could work best for their child. For this reason, we've put together some articles to help families, teachers, and therapists to make decisions on which products would be good to try out!

While we don't sell all of the products listed below in the articles, we still like to provide our insight to help you make decisions!

We do have a massive list of Sensory Toys, but below are some articles dedicated to specific sensory tools and products:

If you're looking to combine multiple sensory toys, tools and products into one space for your child, we would call this a Sensory Room (although it could just be a Sensory Corner of a room).

We have an article dedicated to helping you create a sensory room that can offer different sensory inputs for a variety of sensory play that you can see here.

What Sensory Products Does Harkla Offer?

If you've made it this far in the article, you've obviously into the Sensory World! And if so, might be curious what Sensory Products we offer here at Harkla, if you don't already know!

Want To See All Harkla Products?

Final Thoughts

There’s a lot to know about the ins and outs of sensory processing. This guide is not meant to diagnose your child’s sensory processing disorder, it is intended to help you begin an informed conversation with your occupational therapist about some of the sensory behaviors that are causing you to seek professional guidance.

Think Your Child Might Have Sensory Challenges?

Harkla's in-house Occupational Therapy Assistants have put together a Sensory Challenge Assessment to help parents figure out if looking into sensory integration therapy may be helpful!

Click the button below to take the quick assessment and get recommendations based on your results!




Alescia Ford-Lanza MS OTR/L, ATP is an Occupational Therapist and Assistive Technology Practitioner with over 15 years of pediatric experience. She specializes in educationally-relevant interventions with a focus on sensory integration and assistive technology supports to learning.

Alescia strives to help children by fostering a love of learning and supports families with her parent-friendly, informative blog posts. Alescia founded Adapt & Learn, LLC on the mission that children of all abilities can play, learn, adapt, and develop with the right therapeutic, family, and educational supports.

You can get more information on Alescia and her practice at www.adaptandlearn.com.

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