The Sensory Spectrum & Sensory Processing Disorder

What’s inside this article: An introduction to the sensory spectrum and sensory processing disorders. This is the first part of a 10-part series on sensory processing. Links to detailed articles for each of the 8 sensory systems are at the bottom of this article.

Sensory processing is a normal process where the brain and nervous system receive information from all of the senses and then interpret this information to create appropriate motor and behavioral responses.

Typical sensory processing lets us respond to the input we receive both automatically and appropriately. For most of us, this happens seamlessly. We don’t even think about it.

Everyone processes sensory input differently; the Sensory Spectrum is used to describe the way our bodies uniquely receive and process sensory input.

What Is Sensory Processing Disorder (SPD)?

Sensory Processing Disorder (SPD) is a condition that occurs when the brain has trouble receiving and responding to information from our senses. Sensory signals are not organized and processed into appropriate behavioral responses.

SPD affects approximately 1 in 6 children. It can be a stand-alone condition, or it might be present with other conditions, like autism, attention deficit hyperactivity disorder (ADHD), or learning disabilities.

In fact, 98% of children with autism also deal with a sensory processing disorder.

SPD can affect just one sense, like hearing or multiple senses. And, because the brain is having trouble interpreting this sensory information, children with SPD might behave in ways that are considered inappropriate for their age.

Some people may be overly sensitive to things in their environment, such as sounds, lights, or textures. Others may be under-responsive or not as sensitive to sensory input as others.

Here’s a more detailed breakdown:

Sensory Hyper-Sensitivity (Sensory Avoiding):

Children who are hyper-sensitive may find sensory input overwhelming and might go to great lengths to avoid it. They are more susceptible to sensory overload.

Depending on which sensory systems are affected, avoidance can manifest in different ways. For example, they might cover their ears when they hear loud noises, refuse to wear certain clothing because of how it feels, or be highly picky eaters due to the texture of foods.

Sensory Hypo-Sensitive (Sensory Seeking):

Hypo-sensitive children, on the other hand, are under-responsive to sensory stimuli. These kids may not notice when it’s cold outside, might not respond to their name, or might play really roughly as though they don’t realize their own strength.

Sensory Discrimination Disorder:

This is when individuals have difficulty discerning between different types of sensory input.

For example, they might be unable to tell the difference between hot and cold or have difficulty judging the distance or force needed to interact with objects.

Sensory-Based Motor Disorder:

This includes problems with balance, motor coordination, and the performance of skilled movements due to how the individual perceives sensory information, especially information related to body awareness and movement.

The Sensory Spectrum

The term “the sensory spectrum” describes the array of sensory differences that exist from person to person. How we experience and interpret various stimuli is an individualized experience.

Additionally, we all have sensory preferences. These are things we enjoy and avoid. This is called a sensory bias. It’s the reason why we like different foods, music, activities, etc.

A sensory bias is only a problem when it severely restricts or limits productivity. Or when it chronically interferes with enjoyment in life.

Where do you fit?

We all have what’s known as a neurological threshold, which is our tolerance to sensory input. This is measured by how much input is needed for us to have a reaction. Most of us fall between the two green lines in the diagram above.

If you have abnormaly increased sensitivity, you’re considered hyper-sensitive. Hyper-sensitive people are more likely to experience sensory overload.

In contrast, some people are hypo-sensitive. These individuals may miss important cues from their bodies, like not realizing they are hungry until they are starving.

Hypo-sensitive kids often exhibit a lot of sensory-seeking behaviors, and those who are hyper-sensitive tend to show sensory avoidance. This is covered in more detail throughout this series.

Moreover, a person’s particular placement on the sensory spectrum could vary depending on external and internal factors. For example, I personally fall within the normal range. But, being up all night and waking with a headache increases my sensitivity to sensory input, especially auditory input.

Healthy Development of Sensory Processing

Healthy sensory development begins in infancy.

Learning to lift the head and gain postural control and movement control – learning to sit, stand, and roll – are the very first sensory processing skills to develop as a baby.

Babies will put objects in their mouths, exploring and learning by using the oral-motor system.

They develop the ability to grasp objects, begin responding to noises, and follow their parents’ movements with their eyes.

As children progress into toddlerhood, they begin to learn more complex skills, such as drawing with a crayon, walking, throwing a ball, and self-care skills like dressing.

These are all the foundations of developing efficient sensory processing and integration.

When sensory processing is well developed, it positively influences cognitive development, communication, self-regulation, motor skills, and interactions with the environment.

Sensory Integration Problems

Sensory integration problems include:

Sensory Modulation – The brain either over-responds or under-responds to information, this is the case in kids who are hyper-sensitive and hypo-sensitive to stimuli.
Discrimination and Perception – the brain struggles to interpret sensory information or give meaning to the information. This is the challenge associated with sensory discrimination disorder.
Vestibular Bilateral Functional Problems – Problems related specifically to the vestibular system and coordinating the two sides of the body (bilateral coordination). This is associated with sensory-based motor disorder.
Praxis Problems – Praxis means how the body plans and executes motor movements that it has not done before. This challenge is also present in sensory-based motor disorders.

The 8 Senses

We have 8 sensory systems in our bodies. These are:

Visual (sight)
Auditory (hearing)
Olfactory (smell)
Gustatory (taste)
Tactile (touch)
Vestibular (balance and movement)
Proprioceptive (muscles and joints)
Interoception ( Internal body sensations)

This table shows a brief description of each of the sensory systems (excluding interoception). Individual articles in this series (linked below) will address each system in detail.

The Sensory Spectrum - Description of the sensory systems

Intervention and Treatment for Sensory Processing Disorder

There are many intervention strategies for children struggling with sensory processing. Which intervention strategies work best will depend on your child’s unique sensory needs.

The goal of interventions is to improve sensory processing for the sensory systems that are showing dysfunction. These interventions vary depending on the person.

Intervention often involves occupational therapy with a sensory integration approach, but the specific interventions can vary greatly depending on the individual’s unique needs and the nature of their sensory processing challenges.

However, home and school-based sensory diet plans can greatly benefit children with sensory processing disorders as well. In other words, many strategies can be implemented by parents and educators.

A sensory diet includes specific, scheduled sensory activities and structured leisure time to benefit the individual’s sensory needs.

An occupational therapist creates a sensory diet individualized for your child. However, parents can find many ideas online and, with an understanding of the sensory systems, can find activities that help at home.

Ready to Learn How Each Sensory System Works?

This post is part of a 10-part series on sensory processing and the systems.

Each part will contain a table of contents to help you easily navigate through the entire series.

The Sensory Spectrum and Sensory Processing Disorders