evaluation, lifespan, sensory processing

The Sensory Processing Three Dimensions Scale (SP3D)

Why is getting an accurate and thorough sensory processing disorder (SPD) diagnosis so hard? There are a few major factors, but here’s a big one:

There are virtually no quality clinical tests to assess for it.

Right now, the only clinical tests for SPD are old and outdated and are only for children 8 years old and younger.

Clinicians who have specialized training can use their judgment and reasoning to document signs and symptoms of SPD that are apparent when using other, primarily motor-based assessments or by testing for “soft” signs of neurological impairments. This isn’t always a very accurate method and does not always convince physicians and insurance companies of the validity of an SPD diagnosis.

The only other way of assessing for SPD are questionnaires that have been standardized* (like the Sensory Profile and Sensory Processing Measure), but these are limited by how aware of symptoms the person filling out the questionnaire is (usually a parent, teacher, and/or the person being tested). These questionnaires are also limited in the scope of symptoms assessed and may not provide a complete or accurate picture of symptoms. (*Standardized means the assessment tool has been researched on a sample of people of varying abilities and statistically analyzed to determine what is “typical” and “atypical”.)

Now, here’s the good news: There is a new test in development for clinical assessment of SPD!

The test was developed by clinicians and researchers at the STAR Institute for SPD and the University of New Hampshire and is being published by Western Psychological Services.

The test is called The Sensory Processing Three Dimensions Scale (SP3D) and is the first assessment for SPD with a version for teens and adults. It consists of seven subtests and assesses symptoms of SPD across all three subtypes (sensory modulation disorder, sensory discrimination disorder, and sensory-based motor disorder).

You can help by volunteering to participate in research.

There are several trained clinicians across the United States who are collecting data by giving the assessment to a wide variety of people. You can apply here to see if you qualify to participate!

sensory processing

What is Sensory Processing?

In simple terms, sensory processing and integration are the ways your brain detects, prioritizes, and remembers:

  • External sensations from the environment around you
  • Internal sensations from within your bodies, and
  • Interactive experiences with the people and objects you encounter.
Figure 1. The Sensory Funnel. The way your brain processes information illustrated as a funnel.

Differences in the way your brain has developed gives you a unique set of filters through which you process the sensations you experience. Everyone has subtle differences in the way they process sensations, which are known as your sensory preferences. Here’s a quick overview of how sensory processing works.

Sensory Modulation

Sensory modulation is how your nervous system regulates your brain’s response to sensory stimuli. It is what allows you to perceive a sensation as being too much, too little, or just right. Sensory modulation is related to sensory gating, which is how your brain decides if something is worth paying attention to or not.

When functioning appropriately, sensory modulation alerts you to important information and helps you respond to dangerous situations quickly. However, problems with sensory modulation can lead to a wide variety of challenges.

Sensory Over-Responsiveness

Sensory over-responsiveness (SOR) is also sometimes referred to as sensory sensitivity or being highly sensitive to sensations. An over-responsive reaction to sensations may cause you to easily startle or become overwhelmed by sensations. Sensory over-responsiveness can affect individual sensory systems or the nervous system as a whole.

Figure 2. Sensory Over-Responsive. When you are easily startled or become overwhelmed by sensations.

Sensory Under-Responsiveness

Sensory under-responsiveness (SUR) is also referred to as low registration of sensory input. When you are under-responsive to sensations, you easily miss sensory information unless it is substantial enough to be noticed. Sensory under-responsiveness can affect individual sensory systems or the nervous system as a whole.

Figure 3. Sensory Under-Responsive. When you easily miss sensory information unless it is substantial enough to be noticed.

Sensory Craving

Sensory craving (SC) is often confused with sensory seeking (which is usually an adaptive behavior and not a problem). Sensory craving is more mal-adaptive (addictive or risk-taking) in nature. When your brain cannot detect what or how much sensory input is needed, you are driven to seek out increasing amounts of input, even if doing so leads to negative consequences.

Figure 4. Sensory Craving. When you are driven to obtain increasing amounts of input, despite negative consequences.

Sensory Discrimination

Sensory discrimination is how you filter and categorize sensations. It helps you identify what a sensation is (for example, a sound), determine its qualities (a quiet whisper to my left), and compare and contrast it to other sensations with refined detail (that sounds like my Aunt Mabel).

When functioning well, sensory discrimination allows you to pay attention to and process your experiences. It allows you to discard irrelevant information, catalog things of interest, and remember important details and their attached meanings. Sensory discrimination relies on efficient and reliable sensory modulation abilities, so when you have difficulties with sensory modulation, chances are you have some challenges with sensory discrimination as well.

Here are a few examples of sensory discrimination challenges:

  • May not notice how much is “too much” until too late—you may be overly rough with others, use too much force and break things, or over-stuff your mouth when eating. You may be slow to catch yourself when you trip and fall, talk too loud, or be unable to tell if food is spoiled or not. You may tend to overeat, wait until the last minute to use the bathroom, or not notice signs of hunger or thirst. You may overexert during exercise or yard work, talk excessively, or accidentally overfill containers.
  • May be unable to tell when something is “not enough“—you may tend to run out of things completely before buying more, not clean thoroughly, or use too little pressure when hugging or shaking hands. You may talk too softly, drop things often, or misjudge how much of something is needed when planning ahead or preparing a meal. You may not offer adequate information when communicating with others, not notice when a room is becoming too dark to see, or misjudge how much time it will take to complete a task.
  • May need extra time to form conclusions or come up with questions when learning something new—You may comprehend information on a surface level but have “aha” moments much later. You may ask someone to repeat themselves only to figure it out before the other person finishes repeating what they said. You may not fully understand the meaning of something until a later time. You may not appear to be listening but then surprise others when you say or do something later that demonstrates you were listening after all.

These challenges, along with other similar difficulties with processing sensations are referred to collectively as sensory discrimination disorder (SDD). What is puzzling is that if you have SDD, you may often (though not always) be perceptive of details, but seem to have a hard time making meaning of the information taken in. It can seem like the “filter” in your sensory funnel is clogged. You take in information, and may even comprehend what you are perceiving, but you need time to form conclusions or questions about what you have learned. If you are required to take in too much information for too long, you may experience a form of shutdown that appears as though you are under-responsive to sensations. SDD may cause you to have difficulty prioritizing your responses to sensations, often missing or ignoring your body’s signals until the sensations become intense enough to register as urgent.

Figure 5. Sensory Discrimination Disorder. When it is hard to make sense of incoming information, as if the filter on your sensory funnel is clogged.

Want to know more? Check out The Eight Sensory Systems (that’s right–Eight!). Also, stay tuned for Sensory-Based Motor Disorders, and Why You Should Care About Sensory Processing.