Sensory processing, in plain terms: the eight senses and what difficulty means

The eight systems, including the three you were not taught

Most people learn five senses at school. Practitioners working with children generally describe eight, and the three additional ones do most of the work in explaining what children do in play.

Proprioception, and why children crash into things

Proprioception is the sense that tells you where your limbs are without looking. It comes from receptors in muscles and joints and it is loaded by resistance: pushing, pulling, carrying, climbing, squeezing, hanging.

Heavy work of this kind is widely reported by practitioners and parents as organising and calming, and children frequently seek it out on their own. A child who repeatedly crashes into cushions, wraps themselves in blankets or asks to be squashed is generally doing something purposeful rather than something naughty. The observation is robust; the physiological explanation offered for it is less well established than the confident language around it suggests.

The vestibular sense, and why spinning is not random

The vestibular system sits in the inner ear and reports head position and movement, including the relationship to gravity. It contributes to balance, to eye movement control and to the sense of where "up" is.

Children who seek vestibular input spin, swing, hang upside down, roll down slopes and jump repeatedly. Children who avoid it dislike having their feet off the ground, resist being tipped back, and can find playground equipment genuinely unpleasant rather than merely unfamiliar. Both patterns are common. Intense vestibular input can produce delayed reactions including nausea and disturbed sleep, which is worth knowing before an adult spins a child for a long time because the child asked.

Interoception, the one that explains the toilet

Interoception is the sense of the internal state of the body: hunger, thirst, temperature, pain, and the signals that precede needing the toilet. It is the least discussed of the eight and often the most practically relevant.

Children vary considerably in how clearly they register these signals, and a child who is deeply absorbed in play may not register them at all until they are urgent. This is a routine explanation for accidents in an otherwise reliably toilet-trained child, for a child who does not notice they are cold, and for one who does not eat all day at nursery and then eats enormously at home. It is not defiance and it responds better to prompting and routine than to consequences.

Seeking and avoiding are both strategies

Two broad patterns get described, and most children show a mix that varies by system, by day and by fatigue.

Seeking looks like movement, noise, crashing, touching everything, mouthing objects beyond the usual age, and preferring strong flavours. Avoiding looks like covering ears, refusing textures, disliking crowds, resisting having feet off the ground, and needing to control what touches them.

Neither is misbehaviour. Both are attempts to keep the system at a workable level, and both usually respond better to environmental adjustment than to instruction. Reducing noise, offering a route out of a busy room, allowing movement during listening and building in heavy work before demanding tasks are all low cost and low risk.

The diagnostic question, stated carefully

This is where accuracy matters most. Sensory Processing Disorder is not a standalone diagnostic category in the main manuals used in UK practice. Sensory differences are, however, formally recognised as part of the diagnostic picture for autism, and they appear in the guidance around a number of other conditions.

The practical consequence is that a UK family will rarely be given "sensory processing disorder" as a diagnosis, and may be offered an occupational therapy assessment focused on function instead. That is not a fob-off; function is what interventions can actually change.

On treatment, systematic reviews of sensory integration therapy have generally found the evidence limited, with small studies and inconsistent outcome measures. Some children and families report it helps, and that report deserves respect. It is a different claim from a demonstrated effect, and anyone selling the therapy should be asked which reviews they are relying on.

When to seek an assessment

The threshold is function, not intensity. Ask for help when sensory responses are stopping a child eating a reasonable range of food, wearing weather-appropriate clothing, sleeping, using the toilet, staying in a classroom or joining family activity, and when this is persistent rather than situational.

The route in the UK is a GP or health visitor, or the special educational needs coordinator at the child's setting, who can request an occupational therapy assessment where indicated. What is not a useful route is an online questionnaire that produces a label, because a label without a functional assessment changes nothing that happens on Monday morning.