This guide gives you a complete overview of Sensory Processing Disorder (SPD) including the symptoms, effects on real life, examples, risks and treatment options.
The guide is written by Dolly Bhargava of Behaviour Help which is an NDIS Registered Provider for Behaviour Support and Therapeutic Support (Speech Pathology Services).
What is Sensory Processing Disorder?
SPD affects the way the brain handles sensory information. The different types of sensory information are:
- Tactile (touch),
- Olfactory (smell),
- Gustatory (taste),
- Auditory (sound),
- Visual (sight),
- Proprioceptive (body awareness),
- Vestibular (movement),
- Interoceptive (inner feelings).
Sensory processing refers to the way the brain receives, processes and organises sensory information in order to make sense of the world and produce a response. This sensory information comes from one’s own body and the environment.
Sensory Processing Disorder (SPD) is a neurological condition in which the brain has difficulty with receiving, organising, interpreting and responding to sensory information. SPD can interfere with functioning in everyday life.
SPD can cause a child or adult to be hypersensitive or hyposensitive to sensory stimuli. Hypersensitivity is an oversensitivity or over-responsivity to sensory information, which results in the person reacting strongly to the sensory input. They may not do anything about this themselves, or they may actively engage in behaviour to avoid or escape the stimuli.
Conversely, hyposensitivity is an under sensitivity or under-responsivity to sensory information, which results in the person appearing to not be affected by the sensory stimuli. They may not take any action to gain more input or they may engage in behaviours to actively seek out greater sensory input.
It is important to note a person's responsiveness to sensory information may fluctuate across the day, months or years between being over-responsive and under-responsive to sensory input. Or, the person may display under responsiveness to some stimuli within that sensory system and over-responsiveness to others.
Examples of hyper (over) sensitivity and hypo (under) sensitivity
These are some simple real life examples of children displaying hyper and hypo sensitive behaviour as a result of having Sensory Processing Disorder. For each sense, there is an example of under and over sensitive behaviour.
Under sensitivity to touch:
Ben doesn’t feel the heat when wearing warm clothes on a hot day while Drew isn’t aware of the mess on his skin and clothes.
Oversensitivity to touch
Mia dislikes getting messy or being touched by anyone.
Under sensitivity to visual
Callum has an excessive interest in patterns while Michele is obsessed with bright lights.
Over sensitivity to visual
Renee prefers darkened rooms with little in the way of visual stimulus.
Under / over sensitivity to sound
Jason is fascinated with loud banging whereas Penny is distressed by loud noises.
Under sensitivity to taste
Simon often tastes or licks toys before playing with them.
Over sensitivity to smell
Harriet dislikes the smell of some of her toys and will not play with them.
These are all simple examples of the ways children might behave because of their SPD but they are not necessarily the symptoms.
It is interesting to note that hyposensitivity (under sensitivity) caused by SPD is often misdiagnosed as Attention Deficit Hyperactivity Disorder (ADHD). Some examples include the child’s constant need for movement or touching things or distractibility to auditory and visual stimuli (Star Institute, 2022).
It is important to acknowledge that the child is not choosing the behaviour that can be perceived by others as ‘difficult, oppositional or attention seeking’, rather they are driven to it by their sensory processing needs.
This brings us onto the symptoms of SPD.
Symptoms of Sensory Processing Disorder
Symptoms of SPD typically begin in early childhood, however, young and old adults have also received this diagnosis later in life.
The age of the person is important to consider when looking at symptoms of SPD. This is because very young children, school-age children and adults will exhibit different behaviours as they grow up.
Let’s look at the different symptoms found in three age groups, infants and toddlers, school-aged children and adults.
Symptoms of SPD in infants and toddlers
Symptoms of SPD are often first recognised in infants and toddlers when caregivers notice that the child has difficulties with eating, sleeping, tolerating pain or controlling their body movement.
Here is a full list of what to look for in infants and toddlers as signs of Sensory Processing Disorder:
- Difficulty eating, especially foods of certain smell or texture, for example cheese,
- Difficulty sleeping, trouble falling asleep, staying asleep or frequently waking up,
- Being clingy around parents, guardians or caregivers,
- Seems uncomfortable when being dressed preferring to remain undressed,
- Does not seem to enjoy playing with toys or has trouble playing with toys requiring dexterity,
- Either very tolerant of pain or slow to respond to pain,
- Does not enjoy being held, cuddled or kissed. Often the infant will arch their back to get out of an adult’s hold.
- Clumsy on their feet or with their body in general. The infant might often fall over or bump into objects around them like furniture.
- Easily startled and is difficult to soothe with a pacifier, loved one’s voice or toys,
- Possibly delayed in developmental milestones such as crawling, standing, walking, running or sitting,
- Difficulty being toilet trained
Symptoms of SPD in school aged children
SPD varies from child to child, but some common signs of SPD in school aged children are:
- In constant motion or fidgety.
- Needs to touch everything in their environment.
- Seems unaware of other children or objects in their surroundings and bumps into things constantly or does not notice being bumped by a peer or object.
- Sudden mood changes or tantrums.
- Slow to learn new fine motor skills.
- Difficulty with transitions.
- Spoken language may be hard to understand by others.
- Difficulty making or keeping friends due to overly aggressive play or impassivity.
- Easily distracted.
- Overwhelmed easily during recess (playtime) or in a crowded spaces such as the cafeteria,
- Stumbles over words when reading. The child might be difficult to understand when they are reading aloud.
Symptoms of SPD in adults
SPD symptoms can reveal itself in different ways and it is likely these symptoms have existed since childhood. However, as people grow up and become adults, their behaviours will likely change and so to do the ways SPD affects daily life. These are common SPD symptoms found in adults:
- Frequently overwhelmed by environmental stimuli.
- Begins new tasks frequently but seldom finishes them.
- Needs physical activity to remain focused during the day.
- Must read books and other content several times to understand meaning or instructions.
- Dislikes being messy.
- Sensitive to smells or tastes.
- Discomfort with touch and hugs.
- Seem to be unaware of other children or objects in their surroundings.
- Speech lacks fluency.
- Being picky about clothes, textures, tags or fit.
Sensory Processing Disorder’s effects on life
SPD presents challenges in everyday life that might cause children difficulty keeping pace with peers developmentally or adults difficulty succeeding in work, marriage or community (Star Institute, 2022).
Children may find it difficult to maintain their attention or behave in acceptable ways in education. This often results in problems at school and may limit the child academically as a result.
The same difficulties may also limit a child with social skills which in turn could have an impact on self esteem and play skills which are so often developed alongside peers or friends at a young age.
SPD can also create difficulties for children developing fine, gross and oral motor skills. This might limit certain activities and make communication more challenging.
Even every-day activities like eating, dressing, bathing, sleeping, cutting your nails or participating in leisure activities can be made more challenging by Sensory Processing Disorder for children and adults.
Without appropriate support and services, many individuals with SPD will experience these difficulties. (Ford-Lanza, 2021; Schaaf et al. 2010)
Types of Sensory Processing Disorder
SPD effects all senses and can cause hyper (over) or hypo (under) sensitivity to sensory stimuli. Given that the symptoms and effects are so wide ranging, SPD is organised into categories and subtypes so we can better make sense of the different types of SPD a person may be experiencing.
There are three main categories, they are:
- Sensory Modulation Disorder, SMD
- Sensory Discrimination Disorder, SDD
- Sensory-based Motor Disorder, SBMD
Let’s look at each of these categories to understand how they differ.
Sensory Modulation Disorder, SMD
Sensory modulation is the ability to effectively ignore some components of sensory input while taking notice of others allowing the individual to respond appropriately (Mitchell, et al., 2015).
As such, Sensory Modulation Disorder is the inability to respond appropriately to sensory stimuli because the individual does not have the ability to effectively organize all the sensory input happening at once into manageable groups or ignore certain environmental stimuli but not others.
Put very plainly, for the person with SMD there is too much going on at once and they cannot filter out the noise.
There are three subtypes of SMD, they are:
- Sensory over responsivity, SOR
- Sensory under responsivity, SUR
- Sensory seeking, SS
Sensory over responsivity, SOR
Responses to sensory systems may be aversive or defensive and last longer than one might expect (Mitchell, et al., 2015).
Individuals who fall into this subtype of SMD are uncharacteristically responsive to environmental stimuli and may exhibit excessive behaviors in order to avoid or get away from the overwhelming stimuli. This subtype of SMD is commonly known as sensory defensiveness (Ford-Lanza, 2021).
Sensory under responsivity, SUR
Children with the SUR subtype of SMD are often, as the name suggests, under-responsive to environmental stimuli in comparison to their peers.
They may seem passive to loud noises, such as fireworks or a fire drill, and may appear sluggish or apathetic (Mitchell, et al., 2015).
Sensory Seeking, SS
Sensory seekers fall into their own subtype of SMD due to their insatiable need for sensory stimuli in their environment.
This can lead to extreme behaviors that are disruptive, socially unacceptable, or unsafe (Mitchell, et al., 2015).
Sensory Discrimination Disorder, SDD
SDD is characterized by an individual’s inability to understand the various qualities of sensory stimuli, such as similarities and differences (Mitchell, et al., 2015).
Those with SDD behaviors may demonstrate challenges with motor, language, and/or learning skills (Mitchell, et al., 2015).
Sensory-based Motor Disorder, SBMD
SBMD includes two subtypes, dyspraxia, and postural disorders (Wood, 2020). This category of sensory processing disorder presents with postural instability and impairments in voluntary movement due to problems processing sensory input (Mitchell, et al., 2015).
Dyspraxia is a neurodevelopmental disorder that manifests as difficulties with thinking, planning and executing planned movements or tasks (Pedro & Goldschmidt, 2019).
In short, they have deficits in the ability to conceive ideas for a future concept, such as the timing needed to jump hopscotch or jump rope. Their movements may be awkward and ill-timed, resulting in their appearing “clumsy” to their peers (Mitchell, et al., 2015).
Postural disorder sensory processing deficits result in poor postural development (Mitchell, et al., 2015). These types of individuals may find it intolerable to sit in a chair for longer periods of time.
How Senses are Effected by Sensory Processing Disorder
The eight main senses are all affected by SPD as discussed at the very beginning of this guide. This section explains how each sense is affected by SPD and the effect that has on a person.
How SPD affects Tactile (touch) sense
The tactile sense is one that involves touch, and it is the first sense to develop in utero, continuing to be the dominant sense used to communicate with caregivers during infancy (Hill, 2021).
The tactile sense is part of the nervous system and allows for individuals to “sense, perceive, organize, and integrate information through the receptors on our skin” (Hill, 2021).
Touch involves the processing of light or deep pressure, pain, and temperature and we often associate certain touches as preferable or nonpreferred (Hill, 2021).
For example, children who are hypersensitive may avoid being touched, eating certain textures, wearing specific clothes and engaging in particular self-care tasks (e.g. washing hair, cutting nails).
Whereas children who are hyposensitive will hold on to others tightly, may overfill their mouths as they can’t feel the food in their mouth or touch all surfaces (hot/cold/prickly/sharp) without expressing any discomfort as they may not feel pain or temperature.
How SPD affects Olfactory (smell) sense
Impairments in the olfactory sense, or sense of smell, affect the processing of smells in the environment around them, such as food cooking (or burning!) or a warning of danger with the smell of smoke or chemicals (Ford-Lanza, 2021).
A child with an impairment in their olfactory sense would also experience deficits in their taste buds (Ford-Lanza, 2021). The olfactory sense is directly linked to our sense of taste, memory, and emotions (Hill, 2021).
How SPD affects Gustatory (taste) sense
The gustatory, or taste, sense allows a child to process information in their environment related to how something smells and tastes.
Combined with the sense of smell, children learn and make inferences about their environment based on the texture, temperature, and flavor of food (Ford-Lanza, 2021).
For example, when experiencing a new restaurant, a child might infer the type of food the restaurant serves based on the smell and taste of the food offered to them.
Upon smelling and tasting a tortilla chip or quesadilla, they learn that they are eating Mexican food and might remember the smell of such food in the future in another location, recalling that this type of smell meant that Mexican food was about to be served.
The five basic qualities of taste are sweet, sour, salty, bitter, and savory, and impairments in taste may result in the child’s over or under responsivity to various foods (Hill, 2021).
How SPD affects Auditory (sound) sense
How the body hears stimuli in the environment and turns those sounds into comprehensive messages in the brain (Ford-Lanza, 2021).
The auditory systems affect the brain regions of cochlear nuclei, superior olivary nuclei, lateral lemniscus, inferior colliculus, medial geniculate nuclei, and auditory cortex (Hill, 2021).
Another important function of the auditory system is to filter out unnecessary information, such as multiple conversations occurring at once while in a classroom or public function (Hill, 2021).
Impairments in auditory processing would include the inability to filter out unnecessary sounds in the environment, leading the child to become overwhelmed and unfocused.
How SPD affects Visual (sight) sense
Visual processing refers to the way individuals dissect information gained from sight.
Visual stimuli help children process what they see in the world around them, guiding them to new learning experiences and social connections.
Impaired visual processing would affect a child’s ability to learn and even their vestibular sense, or sense of motion, as riding a bike, walking, or climbing all require visual processes (Hill, 2021).
How SPD affects Proprioceptive (body awareness)
Sometimes referred to as a human’s “sixth sense”, the proprioceptive sense involves the ability to gauge depth such as how far to squat down when sitting in a seat, how high to lift one’s leg when climbing stairs, or how your arm adjusts to properly carry something heavy (Wilson, 2019).
In essence, proprioception allows an individual the ability to always know where their body begins and ends (Wilson, 2019).
Kaviraja (2021) explains the common signs of proprioceptive dysfunction:
- Sensory seeking (pushes, writes too hard, plays rough, bangs or shakes feet while sitting, chews, bites, and likes tight clothes).
- Poor motor planning/Control & Body Awareness (difficulty going up and down stairs, bumps into people and objects frequently, difficulty riding a bike).
- Poor Postural Control (slumps, unable to stand on one foot, needs to rest head on desk while working).
How SPD affects Vestibular (movement)
A less commonly known human sense, the vestibular sense involves change in position, direction, or movement of the head (Ford-Lanza, 2021).
In short, it allows individuals to process information regarding the position of their bodies.
It tells individuals if they are moving fast or slow, with or against gravity, and in what direction they are moving (Ford-Lanza, 2019).
The vestibular sense impacts muscle tone, righting reactions, balance, postural security, eye movements, and overall alertness (Ford-Lanza, 2019).
For example, children with vestibular hypersensitivity can be poor at sports, experience difficulty changing directions, walking or crawling on uneven or unstable surfaces and become anxious if their feet leave the ground.
Children with vestibular hyposensitivity can be described as risk takers and fearless. They enjoy and seek all sorts of movement such as jumping from heights, bouncing, spinning or swinging for a long time without getting dizzy. They may often rock forth and back while standing or sitting.
How SPD affects Interoceptive (inner feelings)
Interoception refers to the ability to perceive and understand internal bodily sensations such as thirst, hunger, feeling hot or cold, running out of breath, experiencing an increased heart rate, or the need to use the bathroom.
A deficiency in the interoceptive sense can cause safety concerns as the person has difficulties with emotional regulation.
A Sensory Processing Disorder ‘Real’ Life Case Study
This case study provides an insight into the behaviours and exhibited symptoms of a child with Sensory Processing Disorder. Often, a person will show a range of symptoms and behaviours consistent with SPD as they go about their day.
Here is an example of a child named Rod, an individual diagnosed with sensory processing disorder.
An occupational therapy assessment has determined that Rod is hypersensitive. He exhibits hypersensitive/overly reactive responses to auditory, tactile, olfactory and gustatory stimuli.
As a result, he avoids these stimuli or attempts to control them as much as possible.
Rod is a resistant eater related to sensory sensitivity to textures, taste, temperature, and smell of the food. Consequently, Rod eats from a limited food selection (total of 10-15 foods).
He exhibits extreme anxiety when presented with new foods and/or foods with strong smells.
For example, he will eat dry foods, corn thins with Nutella, packaged foods such as cupcakes, popcorn, Sprite, Oreo Storm from Hungry Jacks and Ice cream sandwich.
He refuses all hot foods, fruits, vegetables, and anything cooked. He will put his hands over his ears and will look down when in busy areas. He refuses showering, hair cutting, teeth brushing and wears only incredibly old clothing that he has ‘worn in’.
Rod is unable to regulate his body temperature and finds extremes in temperature difficult to cope with. Rod’s sensitivities restrict his ability to engage in everyday activities and others, leading him to isolate himself and then not engage with the environment for learning.
The Relationship Between Sensory Processing Disorder and Other Disorders
SPD can occur in isolation but it can also be comorbid with other disorders. Put another way, a person (child or adult) can be diagnosed with SPD and another disorder such as:
- Autism spectrum disorder (ASD)
- Learning disabilities
- Language disorders
- Head injury or traumatic brain injury (TBI)
- Oppositional defiance disorder (ODD)
The risks of infants born prematurely are still being researched to expand on the concept of premature infants and a correlation with SPD.
Neurosensory development is part of the last processes of growing in-utero babies and takes place in the last 16-20 weeks of gestation (Mitchell, et al., 2015). Therefore, it is believed that SPD develops due to the early cessation of in-utero neurosensory development, as premature infants have not spent enough time in the womb developing their senses to their full extent, as babies born at full term would (Mitchell, et al., 2015).
It is also suggested that SPD could develop after an extended stay in the NICU, exposed to intense stimuli that could alter sensory system development and function (Mitchell, et al., 2015).
Premature infants are defined as those born before 37 weeks and/or have a low, very low, or extremely low birthweight (Mitchell, et al., 2015).
Research appears conflicted on whether or not preterm birth correlates with a later SPD diagnosis.
To date, only four studies have been published examining this concept and their results are somewhat conflicting (Mitchell, et al., 2015).
However, parents whose infants are born prematurely are encouraged to closely monitor their child as they continue to grow for symptoms of sensory processing disorder.
Treating Sensory Processing Disorder
An occupational therapist (OT) is an allied health professional who provides assessment and treatment/therapy to help the individual become as independent as possible in daily activities.
As part of the OT assessment one of the areas that is assessed is how the person is processing and responding to sensory information. The OT will use assessment tools such as a standardised tests (e.g. sensory profile), observations, and caregiver interviews to gather this information.
Based on the results the OT will determine the individual’s sensory preferences and identify sensory strategies to help the individual stay calm and regulated in daily activities by identifying adaptations to the environment, activity and interactions.
The OT will help create a sensory diet for the various environments the individual participates in.
Sensory diets are designed to help children with transitions, feel calmer, and better control and regulate their bodies in a given environment.
This is done through strategically timed sensory activities, such as before, during or after school (Hill, 2022). The idea is to let the individual receive the necessary input at periodic intervals to regulate their body (Hill, 2022).
The OT may also recommend a range of sensory tools that can be used to help the individual stay calm and regulated. For example, weighted vests, or blankets, fidget toys, chewable jewellery and noise cancelling headphones.
Sensory processing disorder is complex in that it has several types and can look different from child to child, depending on their unique sensory needs.
Sensory processing deficiencies can make a “normal looking” child melt down at any given time, often causing judgmental looks from other people who don’t understand the situation.
It is also important to remember that a child’s behavior that is caused by sensory processing difficulties is not being 'attention seeking', 'manipulative or 'naughty' instead they are responding to stimuli that they may find aversive or necessary.
So if you feel you child has sensory processing challenges please get them the help they need through occupational therapy.
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Hill, J. (2021). What is the auditory system? Retrieved from https://harkla.co/blogs/special-needs/auditory-system
Hill, J. (2022). The ultimate guide to sensory diets- activities, templates, and more. Retrieved from https://harkla.co/blogs/special-needs/sensory-diet
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Star Institute (2022). About SPD. Retrieved from https://sensoryhealth.org/basic/about-spd
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