October is National Sensory Awareness Month, and today I’m here to introduce you to the many sensory systems that allow us to participate in and enjoy life!
If you’ve been around kid-land for long, then you’ve probably heard the term “sensory” thrown around here and there. Maybe you’ve heard about sensory exploration, sensory bins, sensory processing/sensory integration, or even Sensory Processing Disorder. Perhaps you’ve even seen sensory play ideas all over social media.
We have more senses than most of us realize (yep, it’s not just the classic five) and, more often than not, we take our body’s ability to deal with sensory input for granted. But processing all the sensory information that comes to our brain from the environment and from within our own body is a complex process.
So what is “sensory processing” (or “sensory integration”)?
A basic explanation of “sensory processing” (also referred to as “sensory integration”) is this — the brain’s ability to organize sensory information coming in from all parts of the body in order to be able to use it. The human body takes in sensory input from several different sensory systems, organizes it in the brain for functional use, and then sends out signals to the rest of the body to activate the appropriate motor, behavior, or emotional responses (known as an “adaptive response”). In individuals with intact sensory processing, this happens automatically, unconsciously, and nearly instantaneously.
A simple example of sensory processing in real life would be when you go to pick up a cup or open a door you think is light (but is actually heavy), you automatically, unconsciously, and nearly instantaneously increase the amount of force you are using in order to actually pick it up or open it. Or if you are walking along a curb and you start to lose your balance, you automatically react to the sensation of being off-balance by either trying to regain your balance or by stepping down off the curb. These are all basic examples of sensory processing in action.
Okay, so now we know what “sensory” means.
Did you know we actually have SEVEN sensory systems?
When occupational therapists talk about sensory processing or sensory integration, we are typically referencing seven sensory systems. Most people have heard of the classic five senses but never knew there are two additional “hidden” sensory systems that play a powerful role in our body’s ability to function on a day-to-day basis. (There are actually more “hidden” sensory systems and receptors as well, such as interoception, but we’ll focus on these ones right now for the purpose of this post).
Here are the seven sensory systems you’ll typically hear OTs talk about:
- Vestibular: Sense of balance and motion, located in the middle ear. At the most basic level, the vestibular system is activated any time we move our head, but it is also continuously being activated by the downward force of gravity to give us a sense of where we are in space. The vestibular system is a very complicated yet powerful sensory system, and there are actually different types of vestibular input depending on what direction or angle your body is moving. Vestibular input can produce a variety of responses. It can be calming, organizing, alerting, or disorganizing depending on the type of movement and the sensitivity of the individual. Occupational therapists with a background in sensory integration are trained to be able to identify what type of vestibular input is needed in different circumstances in order to help produce the desired response needed to improve participation in the task at hand.
- Proprioception: Sense of body awareness. Our body senses proprioception through messages sent from sensory receptors in our muscles and joints. The proprioceptive system is activated any time we push or pull on objects (such as closing or opening a car door), as well as any time the joints are compressed together or stretched apart (such as jumping up and down or hanging on monkey bars). This system helps us understand how much force we are using and whether we need to use more or less force in order to successfully complete the task, such as when coloring, cutting our food with a fork and knife, or opening a door. Proprioceptive input tends to have a calming and organizing effect on the body, particularly when feeling overstimulated or overwhelmed.
- Tactile: Sense of touch, located in sensory receptors in our skin and mouth. Our tactile system has two main functions – to tell us when we’ve touched something (being able to “sense” it) and what it is we’ve touched (being able to “discriminate” its features, such as texture, size, shape, or temperature). Think about how, when you’re digging through your purse or pocket, you first sense that you’ve touched something and then, as you feel more closely, you are able to interpret (or discriminate) the properties of what it is you’ve touched without even having to look at it, whether it’s a certain coin, key, or pen. In addition to the two main functions (sensation and discrimination), the tactile system is responsible for processing light touch (such as when the cat walks by and grazes you with her tail) as well as deep touch (like with a firm handshake or a massage). Light touch tends to be alerting and, for some, alarming. However, deep touch (also called “deep pressure”) tends to be calming and organizing, especially when feeling overstimulated or overwhelmed.
- Visual: Sense of vision, but it’s more than just about being able to see clearly. Our visual system also helps us see what we need to see and filter out what we don’t need to focus on. Visual processing comes into play when tackling tasks such as looking for two matching socks in the laundry pile, scanning a lecture hall or classroom to find an empty seat, or completing a worksheet at school.
- Auditory: Sense of hearing but, again, it’s more than just able to hear accurately. When we process auditory information, our brain has to be able to determine what sounds are important and what sounds can be “tuned out”. It also has to be able to locate where sounds are coming from (Are they in front of me? Behind me? To the side? Nearby? Far away?) and what they mean so we can act or react accordingly. The auditory system is a survival system, and when auditory processing is disordered, it can make people feel disoriented, disorganized, and overwhelmed.
- Olfactory: Sense of smell, influences sense of taste, and is the only sense that is directly tied to the part of the brain responsible for emotional memories (think of the emotions you feel when you smell a familiar smell, whether a positive one like grandma’s cookies baking in the oven, or a negative one like the smell of cologne/perfume that a previous boyfriend/girlfriend used to wear).
- Gustatory: Sense of taste, responsible for detecting all the different flavors that come in the mouth.
These senses work together as a team (in addition to using cognitive skills) in order to help us successfully navigate and participate in our world. For example, visual and vestibular systems work together to facilitate eye tracking in order to do things like reading, writing, and participating in sports. The gustatory, olfactory, tactile, and visual systems work together to allow you to fully appreciate a delicious meal or savory dessert. The proprioceptive and tactile systems work together to tell your body how tightly or loosely to grasp a pencil, how roughly or gently to play with a toy, or how much force to use when picking up or carrying an object. And the proprioceptive, vestibular, tactile, and visual systems work together to facilitate the responses needed in order to kick or catch a ball that’s coming right at you.
When these sensory systems are able to work together and coordinate their efforts, we are then able to function without even realizing how much “work” is being done within our brain. But when the sensory systems have difficulty communicating and working together (aka- “integrating”), then everyday activities such as those mentioned above can become significantly more difficult. This is when we start broaching the topic of “Sensory Processing Disorder”.
Be sure to follow along with Mama OT to learn more about SENSORY and SENSORY PROCESSING DISORDER in the weeks and months to come — what it is, what it isn’t, how it works, and what you can do to help children you know who are struggling with it.