Sensory Processing
You have more than five senses.
Most people learn about five: sight, hearing, smell, taste, touch. But the body also has a sense that tells you where your limbs are without looking at them (this is called proprioception), a sense that tells you about balance and movement (this is called the vestibular sense), and the internal-body sense, interoception.
Eight senses, at least. All of them taking in information, all the time.
For autistic people, the volume on these senses is often set differently. And "differently" really does mean either direction.
Hypersensitivity means that certain inputs arrive much louder, brighter, sharper, or more insistent than they do for most people. A wool jumper that feels scratchy to most people feels like sandpaper. The smell of someone's perfume fills a room that seems, to everyone else, to smell of nothing. The fluorescent light doesn't just look bright; it hums, visibly, in a way nobody else seems to see.
Hyposensitivity means the opposite: inputs that register at full volume for most people arrive faint or barely at all. The same child who cannot tolerate the scratch of a new shoe might not notice when they're bleeding. Someone might seek out very loud music, very deep pressure, very intense movement, because their nervous system needs more input to register the world as present and real.
The same person can be hypersensitive to one thing and hyposensitive to another at the same time. These are not preferences. They are not stubbornness. They are the nervous system's wiring.
Sensory differences were added to the diagnostic criteria for autism in the DSM-5 in 2013, making them officially part of the picture rather than a side note. The foundational work on sensory integration theory was done by Dr. A. Jean Ayres, an occupational therapist and neuroscientist, in the 1970s; her framework for thinking about multiple sensory systems and their integration has shaped how professionals work with sensory differences ever since.
The two directions of difference, hyper and hypo, are both real and both common, and both cause daily difficulty in different ways. Hypersensitivity to sound means school canteens, supermarkets, and birthday parties are exhausting in a way that has nothing to do with social ability. The noise is genuinely louder. It takes more processing. By the end of a noisy school day, a hypersensitive child may have used a great deal of energy simply filtering the auditory environment.
Proprioceptive and vestibular differences are worth mentioning alongside the more visible sensory differences because they're less well understood by most adults. Proprioception is the sense that tells you where your body is in space: whether your feet are below you, whether your arms are at your sides or extended, whether you are sitting upright. When proprioceptive processing is atypical, a child may bump into things more, may need to touch walls or surfaces to feel oriented, may not notice that their posture has collapsed. Vestibular differences affect balance and the tolerance of movement: a child who seems either fearless about spinning and heights, or who cannot bear the sensation of swinging, is telling you something about how their vestibular system calibrates.
The practical question, for parents and teachers, is: what does this particular child's sensory environment actually feel like to them, and what is it costing them to be in it? The answers are often surprising to adults who don't share those sensory profiles. What reads as refusal or behaviour is often, underneath, a body that is working very hard, or trying very hard to find the input it needs.
Making the environment work better is the more effective intervention. Not adapting the child to the environment, but adapting the environment to the child.
- Asking the child what sensory environments are hard and which are comfortable, and believing the answers.
- Modifying environments where possible: softer lighting, noise-cancelling headphones, seamless socks, food separated on the plate.
- Identifying sensory-seeking behaviour (bouncing, spinning, pressing into things) as a need being met, not a problem to stop.
- Giving advance warning before entering sensory-challenging environments.
- "Everyone has to deal with [loud noise / bright lights / scratchy fabric]." (Not at this volume.)
- Removing sensory coping strategies because they look unusual.
- Treating sensory-seeking as misbehaviour.
- Dismissing sensory complaints as attention-seeking or overdramatic.