To add to the complexity, scientists now describe some additional senses! We use our Proprioceptive system to evaluate our position in space and in relationship to other people and objects, so we aren’t always crashing into things. We depend on our Vestibular system for balance and coordination. Our Interoceptive system helps us notice and respond to our own internal cues, so (for instance) we know when we need to eat and when we’re full. And Touch turns out be a complicated system that is always working to assess what our body touches, evaluate cues such as temperature and hardness, and notice and immediately respond to pain, which together we call the Tactile system.
Again, the Proprioceptive, Vestibular, Interoceptive and Tactile systems can function differently from person to person. For instance, some people crave intense physical contact, which seems to ground them. Others perceive a tag in their clothing as so irritating that they can’t focus on anything else until it is cut out. In children, this extreme sensitivity can trigger a big enough “fight, flight or freeze” reaction to result in a massive tantrum.
Sensory Integration is the process that allows the brain, nervous system and senses (including the tactile, proprioceptive and vestibular systems) to work together to perceive the world, organize and interpret these perceptions, and respond appropriately. Healthy sensory development in young children requires activities, notably including complex movement and messy play, that stimulate all of the child’s sensory systems.
Difficulties with Sensory Integration in children can show up as Motor issues (dyspraxia, postural disorder), Sensory Discrimination issues (challenges evaluating sensory information such as how forcefully to push something) or, very commonly, Modulation issues (Sensory Seeking, Avoiding or Under-responding). Sensory seeking children seem to crave stimulation, and are always in motion, touching and bumping into things and people. Sensory avoiders over-react to stimulation, sometimes perceiving physical bumps, noise and bright lights as threats. Sensory Under-responders seem not to notice cues, such as their body shivering or a small cut. It is unfortunately not uncommon for kids with sensory integration issues to have disrupted attachments, because the usual bonding process of touch can be disrupted and connection between parent and child is more challenging.
As many as one in 20 kids has sensory integration challenges. If you suspect that your child might have a sensory processing issue, ask your pediatrician to do a quick assessment. (You can also find checklists online.) Early intervention at the preschool age has the most success since the brain is still forming, but Occupational Therapists who specialize in Sensory Issues are gaining increasing skill in treating sensory issues in people of all ages.