In a series of articles, I will attempt to describe Sensory Processing Disorder (SPD). We will discuss the history of SPD, the eight sensory systems, and the patterns and subtypes of SPD.
In the 1960’s, pioneering occupational therapist, psychologist, and neuroscientist A. Jean Ayres, Ph.D. coined the term Sensory Integration Disorder (SID). In 2004, Lucy Jane Miller proposed that Sensory Integration Disorder be renamed to Sensory Processing Disorder in order to facilitate coordinated research.
Part One: Our Eight Sensory Systems
Sensory Processing Disorder, also called Sensory Integration Dysfunction or Sensory Integration Disorder, is an inability to pull together and understand (or process) sensory input. We receive sensory input through external and internal senses. Difficulty taking in or interpreting this input can lead to problems with daily functioning, social and family relationships, self-regulation, self-esteem, behavior, and/or learning.
Information about our bodies and our world is received through eight primary senses that work in combination to allow us to feel safe, have fun, learn, and interact successfully within our environment. Our eight sensory systems include:
Touch (Tactile System). There are 2 functions of the Tactile System:
- Protective: Allows us to feel pain, temperature, and pressure. For example, this system allows us to pull our hand away when it touches a hot stove.
- Discriminative: Allows us to identify size, shape, and texture without the use of vision. When you put your hand in your pocket and select a quarter from an assortment of change, you are using tactile discrimination.
Body Awareness – (Proprioceptive System or Muscle and Joint Input). Allows us to feel where our body is in space. This system also tells us how much force is needed for a task, such as opening and closing a door, throwing a ball, or applying an appropriate amount of pressure on a pencil.
Movement and Balance (Vestibular System). Allows us to maintain our balance and upright positioning. It also allows us to orient our body in space. Our vestibular system provides information about position changes of the head and information about the speed and direction of movement. It tells us if we are falling and activates our postural muscles to help upright our bodies when needed.
Hearing (Auditory System). Allows us to identify volume, pitch, and directionality of sound.
Sight (Visual System): Allows us to see. Helps to identify objects, judge distance from others, and identify speed of movement to help us navigate through the environment.
Taste (Gustatory System): Allows us to detect sweet, salty, sour, and bitter flavors.
Smell (Olfactory System): Allows us to identify different scents.
Internal Signals (Interoceptive System): Allows us to identify physical sensations of the body; for example, the ability to feel when we need to have a bowel or bladder movement, and the ability to feel hunger or when we are full.
Our five basic senses (sight, smell, touch, hearing, taste) tell us about what is happening in the external world and allow us to acclimate to the environment and adjust to daily demands placed upon us. Our other internal senses allow us to stay connected to what is happening inside our bodies and adjust our responses accordingly. If a person has problems pulling together or understanding this sensory input, the person may experience problems with daily functioning.
Everyone experiences difficulties with pulling together sensory input at one time or another, particularly during periods of growth, change, or stress. However, people who have Sensory Processing Disorder experience these difficulties consistently throughout most of their day. This impacts their performance at home, school, play, and work.
Next week we will focus on SPD patterns and subtypes.
From our family to yours,
Melissa Hough, OTR/L, C/NDT
Owner, Children’s Therapy Center, PSC
Melissa Hough, OTR/L, C/NDT is an occupational therapist with over 20 years of pediatric experience and certifications in Sensory Integration (SI) and Neuro-Developmental Treatment (NDT). Melissa has a professional and personal perspective when working with children because she is also the adoptive parent of a child with special needs.
Since 2002, Children’s Therapy Center, PSC has served thousands of families in Louisville, Kentucky, by providing high-quality therapy services and parent education.