A basic explanation of “sensory processing” (also referred to as “sensory integration”) is this — the brain’s ability to understand sensory information coming 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. The brain then organizes the information for functional use, and then sends out signals to the rest of the body to activate the appropriate motor, behavior, or emotional responses. In individuals with intact sensory processing, this happens automatically, unconsciously, and nearly instantaneously. A simple example 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.
Sensory systems that provide the brain with information include the following:
Vision: it’s more than just about being able to see clearly. Vision is our dominant sense. Vision engages much of the brain. So training your vision is training your brain, not your eyeballs. Vision is the process of deriving meaning from what is seen. It is a complex, learned and developed set of functions that involve a multitude of skills. About 80% of what we learn from the world around us is due to perception, learning, cognition and activities are mediated through vision. The ultimate purpose of the vision is then to act on what we see and respond to that either with our muscles or through cognitive response (understanding). 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.
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.
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.
Auditory: Sense of hearing but, again, it’s more than just being 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.
One of the simplest ways to describe this is to say that, with SPD, the body can respond to sensory input in one of three ways. It can under-respond to sensory input, over-respond to sensory input or seek/crave sensory input. Therapy can help the brain interpret sensory information and put it together with the other senses for accurate responses for the body. Talk with your pediatrician regarding any general concerns and talk to your eye doctor for any vision related concerns.