The 8 Sensory Systems and The Impact of Sensory Processing Disorder

Sensory Processing Disorder (SPD) can change how any one of these systems responds, which is why it helps to know what each one does.⁠^3,13

What are the 8 senses, and what does each one do?

The STAR Institute for Sensory Processing groups the eight sensory systems into three sets: the five basic senses (visual, auditory, olfactory, gustatory and tactile); the three that occupational therapist A. Jean Ayres focused on in describing sensory integration (tactile, vestibular and proprioceptive); and interoception, the most recently discussed, which concerns sensations from the internal organs.⁠¹ Together they let the brain build a picture of what is happening around the body, with it and within it, and where it is.⁠⁶

How many sensory systems are there?

It depends on how finely you divide them. The familiar count is five. The American Academy of Pediatrics describes sensory integration as organizing information from the five senses plus a vestibular sense of balance and a proprioceptive sense of body position, which makes seven.⁠⁴ Neuroscience research in the early 2000s described a dedicated neural system that represents the physiological condition of the body, the basis of interoception, which is counted as the eighth.⁠^1,5 Finer divisions give more: proprioception alone includes senses of limb position and movement, effort, force and heaviness, and the nerve endings that give the coolness of mint and the burn of chili peppers form a common chemical sense separate from taste and smell.⁠^9,10 Eight is the count used in sensory processing work.⁠^1,3

Why are balance, body position and inner senses easy to overlook?

Because they work out of sight. Most people are surprised to learn that they have eight sensory systems rather than five.⁠⁶ Proprioception runs in the background: we stop noticing sensations that are always present, which leaves attention free for other things.⁠¹ It is also what lets someone close their eyes and touch a finger to their nose.⁠⁸ The vestibular system senses head movement and works with the eyes, muscles and joints to coordinate balance automatically.⁠⁷ The STAR Institute calls interoception the eighth, often neglected sensory system, although hunger, thirst and the need to use the toilet all depend on it.⁠¹

What is the sensory system, and how does the brain process sensation?

The sensory system is the set of receptors, nerves and brain areas that detect sensation and turn it into perception. Each sense has its own pathway. Light reaches the retina, where photoreceptors turn it into electrical signals that travel through the optic nerve to the brain, which turns them into the images you see.⁠¹⁵ Sound waves become vibrations, then fluid waves in the cochlea, then electrical signals carried by the auditory nerve.⁠¹⁶ Sensory processing, the brain’s work of registering all this and piecing it together, usually needs no conscious thought.⁠⁶

Sensory integration is the term for how the brain organizes information from the senses and responds appropriately.⁠⁴ Ayres likened sensory processing disorder to a neurological traffic jam that keeps parts of the brain from receiving the information they need to interpret sensation correctly.⁠¹¹

How do the sensory systems work together?

No sense works alone. Balance comes from three inputs, the vestibular organs, the eyes, and the muscles and joints, combined by the brain. Two reflexes link them: one moves the eyes against the head to keep the gaze steady, and one shifts body weight so you do not stumble.⁠⁷ Flavor combines the five basic tastes with smell, the common chemical sense, heat, cold and texture, which is why food tastes bland with a blocked nose.⁠^10,17 Interoception works with the vestibular and proprioceptive senses to shape how a person perceives their own body.⁠¹ Praxis, the ability to plan and carry out purposeful movement, depends on the tactile, vestibular and proprioceptive systems working together.⁠⁶

What does the visual system do?

The visual system is responsible for seeing. Light passes through the front of the eye to the retina, where photoreceptors turn it into electrical signals that the optic nerve carries to the brain.⁠¹⁵ The primary visual area is the occipital lobe at the back of the brain. From there, one stream of information goes to the temporal lobe to work out what objects are, and another to the parietal lobe to work out where they are, covering color, shape, orientation and motion.⁠¹

What does visual sensitivity look like in SPD?

An over-responsive child may find sights overwhelmingly big or intense, and Cleveland Clinic lists reacting to bright lights among common symptoms of SPD.⁠^6,13 Some people register everything around them with the same intensity, so a busy, bright room can feel overwhelming and distracting.⁠⁶ Other children are drawn to visual stimulation: visual fascination with lights or movement is one of the sensory examples in the DSM-5 autism criteria.⁠¹⁸ Visual discrimination difficulties affect interpreting what is seen, such as telling a P from a Q, and can make a child seem inattentive or slow to process.⁠³ More on visual processing disorder.

What does the auditory system do?

The auditory system is responsible for hearing. Sound waves travel down the ear canal to the eardrum, three tiny bones in the middle ear amplify the vibrations, and fluid waves in the snail-shaped cochlea move hair cells that turn the motion into electrical signals for the auditory nerve.⁠¹⁶ Hair cells near the wide end of the cochlea detect high-pitched sounds and those near the center low-pitched ones, and the primary auditory cortex in the temporal lobe maps sound frequencies precisely.⁠^1,16

What does sound sensitivity look like in SPD?

Auditory over-responsivity is one of the most recognizable patterns: covering ears or trying to escape noises such as vacuum cleaners and sirens.⁠^3,19 In 925 children aged 7 to 11, the sounds parents most often said bothered their child were alarms (12%), and sirens and concerts (10% each).⁠¹² Decreased sound tolerance is especially common in autism: a meta-analysis estimated that 41% of autistic people have it at any one time and about 61% at some point in life.⁠²⁰ Under-responsive children may not respond to sounds of ordinary loudness, and auditory discrimination problems make similar sounds hard to tell apart, such as “cat” and “cap.”⁠³ More on noise sensitivity in autism and auditory processing disorder.

What does the olfactory system do?

The olfactory system processes smell. Olfactory sensory neurons in a small patch of tissue high inside the nose each carry one odor receptor and connect directly to the brain. Smells reach them through the nostrils and through a channel from the roof of the throat, which carries the aroma of food as it is chewed.⁠¹⁷ The olfactory bulb, at the front underside of the brain, helps discriminate odors, sharpen their detection and filter out background smells.⁠¹ Smell is also a warning system for gas leaks, spoiled food and fire.⁠¹⁷

What does smell sensitivity look like in SPD?

Over-responsive children may react strongly to smells, one of the sensations that can feel overwhelmingly intense.⁠⁶ Smell also shapes eating: children with tactile defensiveness have been described as refusing foods because of smell, and parents of autistic children name smell as a reason for food selectivity in 36% of cases.⁠²¹ At the other end, excessive smelling of objects is one of the sensory examples in the DSM-5 autism criteria, and olfactory discrimination problems make smells hard to tell apart.⁠^3,18

What does the gustatory system do?

The gustatory system is the sense of taste. Taste cells clustered in the taste buds of the tongue, the roof of the mouth and the throat respond to at least five basic qualities: sweet, sour, bitter, salty and umami, the savory taste of glutamate.⁠¹⁰ Contrary to the familiar tongue map, the different taste cells are scattered across the whole tongue, and we are born with about 10,000 taste buds.⁠¹⁰ The primary taste cortex lies deep in the insula. Taste helps tell safe food from harmful: most people prefer sweet and salty to sour and bitter, and many dangerous substances taste bitter.⁠¹

Taste and smell work closely together. Flavor is the five tastes combined with aroma, texture and temperature, and most people who think they have lost their sense of taste have a problem with smell instead.⁠¹⁰

What does taste sensitivity look like in SPD?

Taste sensitivity rarely acts alone. Parents of autistic children with food selectivity most often named texture (69%), appearance (58%), taste (45%), smell (36%) and temperature (22%) as the reasons.⁠²¹ In children aged 4 to 10, those who disliked how materials felt in their hands also liked foods less, especially the youngest, which suggests that touch sensitivity plays a part in which foods a child accepts.⁠²² Gagging at certain food textures is one of the common symptoms of SPD.⁠¹³ Picky eating is often normal in toddlers, so what matters is how limited and how lasting it is.⁠^21,23 When eating is very restricted, ask about feeding therapy.

What does the tactile system do?

The tactile system processes touch from the whole body. Signals travel through the spinal cord, brain stem and thalamus to the somatosensory cortex in the parietal lobe, which integrates touch, pressure, temperature and pain.⁠¹ Touch is one of the three foundational systems used in sensory integration treatment, and receptors in the skin also contribute to proprioception.⁠^1,9

What does touch sensitivity look like in SPD?

The STAR Institute calls the tactile system extremely important in SPD, because many people with it have tactile defensiveness or under-responsivity to touch and pain.⁠¹ Tactile defensiveness looks like fussing about stiff new clothes and labels, being bothered by sock seams, disliking light touch on the face, and protesting at nail trimming and tooth brushing.⁠¹⁹ In 925 school-age children, the touch sensations parents most often reported as bothersome were tags in clothing (39%), nail cutting (19%), hair brushing (16%) and mud (11%).⁠¹² An under-responsive child may not notice bumps, cuts or scrapes, or whether something is too hot or cold, and a craving child may need to touch everything.⁠^3,13 More on sensory over-responsivity and sensory under-responsivity.

What does the vestibular system do?

The vestibular system senses head movement and gravity. In the inner ear, three semicircular canals detect rotation, such as nodding, shaking or tilting the head, and two otolith organs, the utricle and saccule, detect straight-line movement such as a car speeding up or an elevator rising.⁠⁷ When the head moves, fluid shifts and bends tiny hair cells, which signal the brain through the vestibular nerve.⁠⁷ The system feeds the brain areas that control eye movement and keep the body upright, which is why it matters for balance, a steady gaze and posture.⁠^1,7

What do vestibular difficulties look like in SPD?

Some children are over-responsive to movement, for whom being moved can feel overwhelmingly big.⁠⁶ One recognized pattern is gravitational insecurity: a pilot assessment for it used 15 activities that are fear-inducing for children with the difficulty, scored their avoidance, emotional and postural responses, and correctly classified 83% of them.⁠²⁴ In a twin study, toddlers whose over-responsivity persisted to age seven had more motion sensitivity at four.⁠²⁵ Other children crave movement, and Cleveland Clinic gives a break for spinning or swinging as one sensory activity a therapist may suggest at school.⁠¹³ Vestibular processing also supports posture, and children with postural disorder have difficulty keeping the body stable at rest or in movement.⁠³ More on vestibular and proprioceptive processing and postural disorder.

What does the proprioceptive system do?

Proprioception is the body’s sense of its own position and movement. Mechanoreceptors in the skin, muscles, ligaments, tendons and joints detect stretch, pressure and motion, and the cerebellum, brainstem and sensory cortex combine their signals.⁠⁸ It covers several senses, of limb position and movement, of effort, of force and of heaviness, and limb position comes from populations of receptors rather than single ones.⁠⁹ Proprioception lets you scratch your nose without looking, walk smoothly over gravel and judge how hard to grip a heavy object.⁠⁸

What do proprioceptive difficulties look like in SPD?

Signs of poor proprioception include clumsiness, bumping into things, uncoordinated movement, balance problems, and using too much or too little force, such as pressing too hard when writing.⁠⁸ Cleveland Clinic lists sensory processing disorders, including dyspraxia, postural disorder and sensory under-responsivity, among the conditions that affect proprioception.⁠⁸ Under-responsivity to touch and deep pressure can lead to poor body awareness and movements that are not graded well.⁠³ Ayres considered proprioception, with the vestibular sense, a foundation of sensory integration difficulties, and therapists trained in sensory integration build treatment around it.⁠¹ More on dyspraxia.

What does the interoceptive system do?

Interoception is the sense of the body’s internal state. Researchers define it as the process by which the nervous system senses, interprets and integrates signals from within the body, moment to moment, at conscious and unconscious levels.⁠²⁶ Examples include a full bladder, hunger, thirst, nausea, itchy skin, muscle tension, a heartbeat, and feeling hot or cold. A sensor detects the signal, the thalamus relays it and the insula decodes it.⁠² The neuroscientist A. D. Craig described this system as a representation of “the material me” that might underlie feelings, emotion and self-awareness.⁠⁵

Interoception is learned. Children gradually learn to feel the need to pee or poop and to know when to use the toilet, and the skill varies a lot from person to person.⁠²

What do interoceptive differences look like?

Signs that interoception is not working as expected include difficulty knowing when the bladder is full, not feeling hungry, thirsty or full, a high or low pain tolerance, difficulty managing emotions and feeling easily anxious.⁠² Interoceptive differences are reported in autism, ADHD and anxiety disorders; a review found interoception atypical in autism, with a slight tendency toward under-responsiveness.⁠^2,27 Problems with interoception are increasingly recognized in anxiety, mood and eating disorders too.⁠²⁶ More on interoception.

How does sensory processing disorder affect the eight senses?

Sensory processing disorder is a difference in how the brain understands and responds to information from the senses.⁠¹³ It can affect a single sense, such as touch, sight or movement, or several.⁠¹¹ The STAR Institute describes patterns that can show up in any of the eight systems:⁠³

Estimates of how many children are affected range from 5% to 16%.⁠^6,12,28 What causes SPD is still being studied, and twin studies point to a partly inherited tendency.⁠^13,19 In toddlers the signs look different at each age, as the guide to sensory processing disorder in toddlers sets out.⁠²⁹

Can one child be both over- and under-responsive?

Yes. A person can have heightened sensitivity in some systems and reduced sensitivity in others, and even both within one system.⁠⁶ Some register everything with the same intensity, so a teacher’s voice, a ticking clock and the air conditioner all compete for attention, and they can look either under-responsive or overwhelmed.⁠⁶ Sensory processing can also fluctuate with stress, fatigue or surroundings.⁠⁶ More on over-responsivity and under-responsivity.

Is sensory processing disorder an official diagnosis?

Not yet. Cleveland Clinic notes that SPD is not an official medical diagnosis, and the American Academy of Pediatrics has advised that it generally should not be diagnosed because there is no universally accepted framework.⁠^13,30 Sensory reactivity is part of the DSM-5 criteria for autism, and the DC:0-5 manual for early childhood lists sensory over- and under-responsivity disorders.⁠^18,31

How is sensory processing assessed?

An occupational therapist usually assesses sensory processing, often after a pediatrician’s referral, by watching how the child responds to sensory experiences and asking about symptoms, behavior and history.⁠¹³ Standardized questionnaires help: the Sensory Profile 2 covers birth to 14 years 11 months, with caregivers and teachers reporting how the child responds to sensory events through the day.⁠¹⁴ Because sensory difficulties also occur in autism, ADHD, developmental coordination disorder and anxiety, the AAP asks that other conditions always be considered.⁠³⁰ More on testing for sensory processing disorder.

What helps a child with sensory processing difficulties?

Occupational therapy is the main treatment. There is no cure, but therapy helps children with motor skills, self-care, play and self-regulation.⁠¹³ Sensory integration therapy, developed by Ayres in the 1970s, uses play with equipment such as swings, trampolines and slides.⁠⁴ The evidence is strongest for autistic children working on their own goals with Ayres Sensory Integration.⁠^32,33 For specific techniques, a 2025 review found strong evidence for deep pressure touch and for training caregivers, and moderate evidence that working on several sensory systems helps more than working on one.⁠³⁴ The AAP calls the research limited and suggests a trial period with a clear way to judge the result.⁠³⁰ More on sensory integration therapy and sensory diets.

Everyday adjustments depend on the sense involved. At school, Cleveland Clinic gives examples such as headphones to block background noise, fidget toys and a break to walk, spin or swing.⁠¹³ Because training caregivers has strong evidence, understanding and support from the family is part of treatment.⁠³⁴ You can find a pediatric occupational therapist by city and state.

RelatedTypes of SPDSensory seekingSensory processing quiz

Sources

1. STAR Institute for Sensory Processing. Your 8 Senses. Sensoryhealth.org, undated. Checked October 11, 2026.
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   The page groups “The five basic sensory systems” (visual, auditory, olfactory, gustatory, tactile), “The three sensory systems Ayres focused on in describing sensory integration dysfunction” (tactile, vestibular, proprioceptive) and “The most recently discussed set of sensations related to internal organs” (interoception). Vision: “The primary visual area of the brain is the occipital lobe”; “Types of visual information include: color, shape, orientation, and motion. From the ventral stream in the occipital lobe information projects to the temporal lobe to process what objects are. From the dorsal stream, information goes to the parietal lobes to process where objects are located.” Hearing: “The primary auditory cortex is located in the superior temporal gyrus of the brain”; “Specific sound frequencies can be mapped precisely onto the primary auditory cortex.” Smell: “The olfactory bulb is located in the most forward part of the brain on the bottom side of the brain”; its functions include “discriminating among odors”, “enhancing detection of odors” and “filtering out many background odors”. Taste: “It allows us to discriminate between safe and harmful foods. Usually, individuals prefer sweet and salty tastes to sour or bitter tastes”; “many dangerous pharmacological agents taste bitter”; “The primary gustatory cortex is located near the somatotopic region for the tongue, in the insular cortex”. Touch: “The body sends tactile information to the somatosensory cortex through neural pathways to the spinal cord, the brain stem, and the thalamus”; “the somatosensory cortex is the part of the nervous system that integrates touch, pressure, temperature, and pain. The tactile system is extremely important in SPD. Many individuals with the disorder have tactile symptoms such as tactile defensiveness or under-responsivity to touch and pain. The touch system is one of the three foundational systems used in sensory integration treatment.” Vestibular: “The vestibular system contributes to balance and orientation in space. It is the leading system informing us about movement and position of head relative to gravity”; “The vestibular system sends signals primarily to the neural parts of the brain that control our eye movements, and that keep us upright.” Proprioception: “Proprioception was felt by Ayres to be the foundation (with vestibular impairments) of SPD. It is one of the three sensory systems used by SI trained therapists as the cornerstone of the sensory aspect of advanced treatment”; “Generally speaking we do not notice out proprioceptive sense because we disregard through habituation, desensitization, or adaptation sensory stimuli that is continuously present”; “One practical advantage of this is that unnoticed sensation continue in the background while an individual’s attention can move to another concern.” Interoception: “The eighth, often neglected, but frequently problematic sensory system in SPD is the Interoceptive System”; “Hunger and thirst are examples of interoception. Interoception detects responses that guide regulation, including hunger, heart rate, respiration and elimination”; “Interoception works the vestibular and proprioceptive senses to determine how an individual perceives their own body.”
2. Cleveland Clinic. Interoception. Health Library, last updated February 19, 2025. Checked October 11, 2026.
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   “Interoception is the understanding of your body’s internal senses. You can feel that you’re hungry, that your heart is beating or that you need to pee. It’s a learned skill that you develop as you grow.” “As you grow and develop, you learn more about what important interoception skills are necessary, like feeling the need to pee or poop and knowing when to use the toilet.” Examples: “A full bladder”, “Hot or cold temperatures”, “Hunger”, “Itchy skin”, “Muscle tension”, “Nausea”, “Thirst”, “Your heartbeat”. The thalamus receives the signal and “sends the information to the insula to decode it”. “It varies significantly from person to person.” Signs of poor interoception: “Difficulty knowing when your bladder is full (when you need to pee)”, “Difficulty managing emotions”, “Feeling easily anxious”, “Having a high or low pain tolerance”, “Not feeling hungry or thirsty or not feeling full after a meal”; conditions that affect it include anxiety disorders, ADHD and autism. The first step: “An interoceptor (sensor in a neuron/nerve cell) detects a signal.”
3. STAR Institute for Sensory Processing. Patterns or Subtypes of Differences in Sensory Integration & Processing. Sensoryhealth.org, undated. Checked October 11, 2026.
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   “These differences can affect multiple sensory systems, including visual, auditory, tactile, olfactory, gustatory, vestibular, proprioceptive, and interoceptive modalities.” The three major patterns are sensory modulation, sensory discrimination and sensory-based motor differences. Sensory over-responsive: “Predisposition to respond more intensely, quicker, and/or longer to sensory stimuli.” Sensory under-responsive: “Predisposition to respond less intensely to sensory stimuli, to have a delay before responding, and/or responses are muted.” “Individuals with sensory over-responsivity are more sensitive to sensory stimulation than most people. Their bodies feel sensation more easily and/or more intensely. They might feel as if they are being constantly bombarded with information. Consequently, these people often have a ‘fight or flight’ response to sensation, e.g. being touched unexpectedly or loud noise”; “They may try to avoid or minimize sensations, e.g. withdraw from being touched or cover their ears to avoid loud sounds.” “Individuals who are under-responsive to sensory stimuli require more intensity and repetition of sensation than others. They may appear quiet and passive, oblivious or not responding to stimuli of the usual intensity available in their sensory environment. Their under-responsivity to tactile and deep pressure input may lead to poor body awareness, clumsiness or movements that are not graded appropriately. These children may not perceive objects that are too hot or cold or they may not notice pain in response to bumps, falls, cuts, or scrapes.” Sensory discrimination: “(Do I see a ‘P’ or a ‘Q’? Do I hear ‘cat’ or ‘cap’?”); “Individuals with poor sensory discrimination may appear awkward in both gross and fine motor abilities and/or inattentive to people and objects in their environment. They may take extra time to process the important aspects of sensory stimuli.” Discrimination differences are listed for auditory, visual, tactile, vestibular, proprioceptive, gustatory, olfactory and interoceptive sensation. “An individual with postural disorder has difficulty stabilizing his/her body during movement or at rest”; people with dyspraxia “have trouble processing sensory information properly, resulting in problems planning and carrying out new motor actions ... These individuals are clumsy, awkward, and accident-prone. They may break toys, have poor skill in ball activities or other sports, or have trouble with fine motor activities. They may prefer sedentary activities”.
4. American Academy of Pediatrics, HealthyChildren.org. Sensory Integration Therapy. Last updated October 7, 2019; adapted from the AAP book Autism Spectrum Disorders: What Every Parent Needs to Know. Checked October 11, 2026.
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   “Sensory integration is a term that has been used to describe processes in the brain that allow us to take information we receive from our 5 senses, organize it, and respond appropriately. We also have a vestibular sense (balance) that tells us how to position our bodies and heads, and a proprioceptive sense (awareness of body in space) that helps us know what we do with our joints, muscles, and ligaments.” “Some children will look for ways to seek out certain sensations and engage in self-stimulating behaviors like rocking back and forth, head banging, and oral exploration of nonedible objects.” “Sensory integration therapy, which was developed in the 1970s by an OT, A. Jean Ayres”; “Therapy sessions are play-oriented and may include using equipment such as swings, trampolines, and slides.” “You may also learn about auditory integration training or behavioral optometry as methods for controlling sensory input”; “neither method has proved to be scientifically valid.”
5. Craig AD. How do you feel? Interoception: the sense of the physiological condition of the body. Nature Reviews Neuroscience. 2002;3(8):655–666. PMID 12154366. Checked October 11, 2026.
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   The abstract: “Recent functional anatomical work has detailed an afferent neural system in primates and in humans that represents all aspects of the physiological condition of the physical body. This system constitutes a representation of ‘the material me’, and might provide a foundation for subjective feelings, emotion and self-awareness.”
6. STAR Institute for Sensory Processing. Understanding the Sensory Integration Process. Sensoryhealth.org, undated. Checked October 11, 2026.
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   “Studies indicate that 5% to 16% of children exhibit symptoms of SPD.” “Our bodies and brains use specialized systems to register all the different sensory information in our environment and piece it together to build a complete picture of: what is going on around us, with our bodies, within our bodies, where we are, and what time of day it is.” “Our ability to process sensory data does not usually require conscious thought or cognitive effort.” “In the early years of life, there are very few, if any, experiences that are not deeply sensory in nature.” “Also through play as we knock over blocks, shake a musical rattle, and drop items off the high chair tray.” “We develop sense-of-self through these early experiences, we learn how to solve problems, we learn that we can impact objects and people”; “We also develop motor skills”. “Most people are surprised to find out that we actually have eight sensory systems rather than five.” “Heightened Sensitivity: Some neurodivergent individuals experience heightened sensitivity to sensory input. This can make sounds, sights, smells, being moved or moving, and even internal sensations feel overwhelmingly ‘big,’ ‘loud,’ or ‘intense.’” “you can have heightened sensitivity to some sensory systems and reduced in others. You may even have some higher and lower responsivity within one system”; “Some register everything around them with the same level of intensity”, so that “the teacher’s voice, the ticking of the clock, the buzzing of the air conditioner, and the bell signaling time for transition may all be equally intense”. “Praxis is the ability to plan and carry out purposeful movements. This skill is essential for everything from learning to roll over, to riding a bike”; “Effective praxis depends on the integration of our tactile, vestibular, and proprioceptive systems”. “Sensory processing isn’t static; it can fluctuate based on factors like stress, fatigue, or environmental changes.”
7. Cleveland Clinic. Vestibular System. Health Library, last updated June 19, 2024. Checked October 11, 2026.
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   “The vestibular apparatus within your inner ear includes five vestibular organs: Three semicircular canals. Two otolith organs.” “Vestibular organs inside your inner ear sense your head movements and send this information to your brain.” The canals “detect rotational head movements” (nodding, shaking and tilting the head); the utricle “Detects horizontal motion (forward or back, like being in a moving car)” and the saccule “Detects vertical movement (up or down, like being in a moving elevator)”; “Your otolith organs are two chambers that detect linear movements (those related to gravity).” “When your head moves, the endolymph shifts, causing the hair cells to shear or move. As a result, the hair cells send sensory information about your movement to your brain.” “The nerve signals travel via an important structure called the vestibular nerve”. “It works closely with your eyes, muscles and joints to coordinate balance functions automatically.” “Based on these three inputs (vestibular system + eyes + muscles and joints), your brain sends signals that tell your body how to remain in balance.” The vestibulo-ocular reflex lets “your eyes moving opposite of your head to maintain your gaze”; the vestibulospinal reflex “causes your body weight to shift in response, so you don’t stumble.”
8. Cleveland Clinic. Proprioception. Health Library, last updated July 25, 2024. Checked October 11, 2026.
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   “Proprioception is your body’s ability to sense its own position and movements. It’s an automatic or subconscious process.” “Mechanoreceptors are in your skin, muscles, ligaments and tendons, and near your bones and joints. They can detect various forms of stimuli, like touch, pressure, stretching, vibration and motion.” “Several parts of your brain work together to process sensory information, especially the cerebellum, brainstem and sensory cortex.” “people with a healthy sense of proprioception can close their eyes and accurately touch their fingers to their noses.” Examples: walking on uneven gravel, scratching the nose without looking, and “If you’re holding a heavy object, your body knows how much strength (force) you need”. Signs of poor proprioception include “Balance issues”, “Clumsiness, like accidentally running into objects around you”, “Uncoordinated movements” and “Using too little or too much force for actions (like using too much pressure when writing)”; conditions that affect it include “Sensory processing disorders, including dyspraxia, postural disorder and sensory under-responsivity (SUR)”.
9. Proske U, Gandevia SC. The proprioceptive senses: their roles in signaling body shape, body position and movement, and muscle force. Physiological Reviews. 2012;92(4):1651–1697. PMID 23073629. Checked October 11, 2026.
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   The abstract: the proprioceptive senses “include the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. Receptors involved in proprioception are located in skin, muscles, and joints. Information about limb position and movement is not generated by individual receptors, but by populations of afferents.”
10. National Institute on Deafness and Other Communication Disorders. Taste Disorders. NIDCD health information, undated. Checked October 11, 2026.
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    “These taste cells, or gustatory cells, are clustered within the taste buds of the tongue and roof of the mouth, and along the lining of the throat.” “At birth, you have about 10,000 taste buds”. “Taste cells have receptors that respond to one of at least five basic taste qualities: sweet, sour, bitter, salty, and umami”; “A common misconception is that taste cells that respond to different tastes are found in separate regions of the tongue. In humans, the different types of taste cells are scattered throughout the tongue.” “Another chemosensory mechanism, called the common chemical sense, involves thousands of nerve endings ... These nerve endings give rise to sensations such as the coolness of mint and the burning or irritation of chili peppers.” “When you eat, the sensations from the five taste qualities, together with the sensations from the common chemical sense and the sensations of heat, cold, and texture, combine with a food’s aroma to produce a perception of flavor.” “Most people who think they have a taste disorder actually have a problem with smell.” “Without smell, foods tend to taste bland and have little or no flavor.”
11. STAR Institute for Sensory Processing. About SPD. Sensoryhealth.org, undated. Checked October 11, 2026.
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    “Sensory Processing Disorder (SPD), exists when sensory signals are either not detected or don’t get organized into appropriate responses.” Ayres “likened SPD to a neurological ‘traffic jam’ that prevents certain parts of the brain from receiving the information needed to interpret sensory information correctly.” “for children, adolescents, and adults with SPD, these difficulties are chronic, and they can significantly disrupt everyday life.” “Sensory Processing Disorder can affect people in only one sense–for example, just touch or just sight or just movement–or in multiple senses.” “Many worry that they are somehow to blame for their child’s sensory issues.” “Preliminary research suggests that SPD is often inherited.” “Prenatal and birth complications have also been implicated, and environmental factors may be involved.”
12. Ben-Sasson A, Carter AS, Briggs-Gowan MJ. Sensory over-responsivity in elementary school: prevalence and social-emotional correlates. Journal of Abnormal Child Psychology. 2009;37(5):705–716. PMID 19153827. Checked October 11, 2026.
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    In “a representative sample of elementary school-aged children (n=925, 50% boys, ages 7–11 years) who were followed from infancy. Sixteen percent of parents reported that at least four tactile or auditory sensations bothered their children”; “Parents of children with versus without elevated SOR in school-age reported higher frequencies of early and co-occurring internalizing, externalizing, and dysregulation problems, and lower levels of concurrent adaptive social behaviors.” “The sensations that parents reported bothered children most frequently were tactile, with the most frequently reported tactile sensations being: tags in clothing (39%), cutting finger or toe nails (19%), hair brushing (16%), and mud (11%)”; “the most frequent sounds being alarms (12%), sirens, and concerts (both 10%)”; “Fifty percent of school-age children were bothered by one to three sensations.”
13. Cleveland Clinic. Sensory Processing Disorder (SPD). Health Library, last updated March 20, 2025. Checked October 11, 2026.
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    “Sensory processing disorder (SPD) is a difference in the way your brain understands and responds to information from your senses. This includes what you see, hear, smell, taste and touch. It can also affect your movement.” “Healthcare providers and parents typically identify SPD in children. But it can also affect adults. SPD commonly affects people with neurodevelopmental and neurodivergent conditions, like autism spectrum disorder and attention-deficit/hyperactivity disorder (ADHD). But you can also have SPD without any other condition.” “Currently, SPD isn’t an official medical diagnosis. But providers recognize the benefits of identifying SPD and using therapy to manage it, especially if it affects your ability to function day to day.” Sensory under-responsivity: “You may be unaware of sensory information and/or have a delay before responding, compared to most people.” Sensory craving: “In this type, you need and seek out sensory information for stimulation. But getting the stimulation results in disorganization and doesn’t satisfy the craving.” Common symptoms include “Constantly bumping into things (clumsiness)”, “Gagging when eating certain food textures”, “Needing to constantly touch things”, “Not recognizing personal space” and “Reacting to sudden movements, touches, loud noises and/or bright lights.” “Researchers don’t yet know the cause of sensory processing disorder. Studies show that genetics and environmental factors likely play a role.” “your child’s pediatrician may refer you to an occupational therapist. These professionals can assess your child for SPD by watching them interact with certain sensory experiences. They’ll also ask about your child’s symptoms, behavior and medical history to help in the diagnosis. Your pediatrician may also refer you to other specialists”. “There’s no cure for sensory processing disorder. But various types of occupational therapy can help manage the symptoms of SPD”; therapists help children “Meet developmental milestones (for children), like fine and gross motor skills”, “Improve self-care and activities of daily living”, “Improve play and social skills” and “Improve self-regulation skills and behavior.” “your child’s occupational therapist may recommend incorporating routine sensory activities and tools at home and school”, for example “Access to headphones to block out background noises while they work”, “Access to fidget toys” and “A designated break to do a sensory activity, like walking, spinning or swinging.”
14. Pearson Assessments. Sensory Profile 2. Product page for the questionnaires by Winnie Dunn, published 2014. Checked October 11, 2026.
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    The family of assessments “provides standardized tools to help evaluate a child’s sensory processing patterns in the context of home, school, and community-based activities.” “Age range: Birth–14:11”; “caregivers and teachers report on the child’s response to sensory events throughout the day”; the forms are “Infant, Toddler, Child, Short, and School Companion”.
15. National Eye Institute. How the Eyes Work. Last updated April 20, 2022. Checked October 11, 2026.
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    “When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals.” “These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.”
16. National Institute on Deafness and Other Communication Disorders. How Do We Hear? Last updated March 16, 2022. Checked October 11, 2026.
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    “Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum.” “The bones in the middle ear amplify, or increase, the sound vibrations and send them to the cochlea, a snail-shaped structure filled with fluid, in the inner ear.” “Hair cells near the wide end of the snail-shaped cochlea detect higher-pitched sounds, such as an infant crying. Those closer to the center detect lower-pitched sounds”; “The auditory nerve carries this electrical signal to the brain, which turns it into a sound that we recognize and understand.”
17. National Institute on Deafness and Other Communication Disorders. Smell Disorders. NIDCD health information, undated. Checked October 11, 2026.
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    “Your sense of smell is also a warning system, alerting you to danger signals such as a gas leak, spoiled food, or a fire.” “Your ability to smell comes from specialized sensory cells, called olfactory sensory neurons, which are found in a small patch of tissue high inside the nose. These cells connect directly to the brain. Each olfactory neuron has one odor receptor.” “Smells reach the olfactory sensory neurons through two pathways. The first pathway is through your nostrils. The second pathway is through a channel that connects the roof of the throat to the nose. Chewing food releases aromas that access the olfactory sensory neurons through the second channel.”
18. Centers for Disease Control and Prevention. Clinical Testing and Diagnosis for Autism Spectrum Disorder. Page dated May 8, 2025, reproducing the DSM-5 criteria. Checked October 11, 2026.
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    “To meet diagnostic criteria for ASD according to DSM-5, a child must have persistent deficits in each of three areas of social communication and interaction (see A.1. through A.3. below) plus at least two of four types of restricted, repetitive behaviors (see B.1. through B.4. below).” B.4: “Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment (e.g. apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement).”
19. Goldsmith HH, Van Hulle CA, Arneson CL, Schreiber JE, Gernsbacher MA. A population-based twin study of parentally reported tactile and auditory defensiveness in young children. Journal of Abnormal Child Psychology. 2006;34(3):378–392. PMID 16649001. Checked October 11, 2026.
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    “Using a population-based sample of 1,394 toddler-aged twins, mothers reported on tactile and auditory defensiveness, temperament, and behavior problems”; “Girls were overrepresented in the extreme tactile defensiveness group. Both auditory and tactile defensiveness were modestly associated with fearful temperament and anxiety, but they were relatively distinct from other common dimensions of childhood behavioral dysfunction.” The symptoms “occur not only in subsets of children with ADHD, autism, and Fragile X syndrome, but also in the apparent absence of accompanying disorders.” “Some children fuss about stiff new clothes, turtleneck sweaters, and labels sewn inside collars. These children may be bothered by the seams of socks, dislike being touched lightly on the face, protest vigorously to fingernail trimming and tooth brushing”; “highly aversive reactions to vacuum cleaners and sirens, might indicate ‘auditory defensiveness.’” “Heritability was calculated at 38%, shared environment accounted for 33% of the variance” for auditory defensiveness; “For tactile defensiveness, the heritability was 52%”.
20. Williams ZJ, Suzman E, Woynaroski TG. Prevalence of decreased sound tolerance (hyperacusis) in individuals with autism spectrum disorder: a meta-analysis. Ear and Hearing. 2021;42(5):1137–1150. PMID 33577214. Checked October 11, 2026.
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    Hyperacusis is “decreased tolerance to sound at levels that would not trouble most individuals”; “The meta-analysis of interview/questionnaire measures (k(3) = 103, nASD=13093) estimated the current and lifetime prevalence of hyperacusis in ASD to be 41.42% (95% CrI [37.23, 45.84]) and 60.58% [50.37, 69.76], respectively.”
21. Cermak SA, Curtin C, Bandini LG. Food selectivity and sensory sensitivity in children with autism spectrum disorders. Journal of the American Dietetic Association. 2010;110(2):238–246. PMID 20102851. Checked October 11, 2026.
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    “Although picky eating is not uncommon among young children who are typically developing, pickiness in children with autism spectrum disorders (ASDs) may be even more restrictive”; “the factors parents felt influenced food selectivity were: texture (69%), appearance (58%), taste (45%), smell (36%), and temperature (22%)”. Of children with tactile defensiveness who did not have autism: “The children with tactile defensiveness were reported to have a fair to poor appetite, hesitated to eat unfamiliar foods, did not eat at other people’s houses, and refused certain foods because of smell and temperature. They also were resistant to eating vegetables, with overall vegetable consumption being half that of children without tactile defensiveness.”
22. Nederkoorn C, Jansen A, Havermans RC. Feel your food. The influence of tactile sensitivity on picky eating in children. Appetite. 2015;84:7–10. PMID 25261102. Checked October 11, 2026.
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    The abstract: “44 children between the ages of 4 and 10 were asked to feel different tactile stimuli with their hands and to taste different foods. Results showed a significant positive correlation between the evaluations of the two modalities, especially for the younger subjects. This suggests that tactile sensitivity might play a role in the acceptance of food.”
23. American Academy of Pediatrics, HealthyChildren.org. 10 Tips for Parents of Picky Eaters. AAP Committee on Nutrition; last updated April 26, 2018. Checked October 11, 2026.
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    “Picky eating is often the norm for toddlers.” “A toddler’s favorite food one day may hit the floor the next”; “For weeks, they may eat 1 or 2 preferred foods – and nothing else.” “Pressuring kids to eat, or punishing them if they don’t, can make them actively dislike foods they may otherwise like.” “It can take as many as 10 or more times tasting a food before a toddler’s taste buds accept it.” “use what nutritionists call ‘food bridges’ to introduce others with similar color, flavor and texture”. “If you are concerned about your child’s diet, talk with your pediatrician, who can help troubleshoot and make sure your child is getting all the necessary nutrients to grow and develop.”
24. May-Benson TA, Koomar JA. Identifying gravitational insecurity in children: a pilot study. American Journal of Occupational Therapy. 2007;61(2):142–147. PMID 17436835. Checked October 11, 2026.
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    The abstract: “The GI Assessment consisted of 15 activities that created conditions characterized as fear-inducing for children with gravitational insecurity. Three behavioral categories-avoidance, emotional, and postural responses--were scored for each activity”; “Discriminant analysis classified 83% of the gravitationally insecure group and 100% of the typical group.”
25. Van Hulle C, Lemery-Chalfant K, Goldsmith HH. Trajectories of sensory over-responsivity from early to middle childhood: birth and temperament risk factors. PLoS One. 2015;10(6):e0129968. PMID 26107259. Checked October 11, 2026.
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    Twins from the Wisconsin Twin Project, “a population-based, typically developing sample of twins (N=978)”, assessed “at age two years via a caregiver report temperament questionnaire and again at age seven years via a sensory over-responsivity symptom inventory”; “294/3058 (9.4%) of children screened positive for SOR at age two years”; “Roughly equal numbers of males and females screened positive for SOR in toddlerhood (152 girls, 142 boys”). Trajectory groups: “low symptom (N=768), remitted (N=75), late-onset (N=112), and chronic (N=24)”; “Children in the chronic group had more severe symptoms of sensory sensitivity at age four years, including more motion sensitivity” and “had a younger gestational age and were more likely to be low birth-weight than the low symptom group.” “Sensory over-responsivity was modestly correlated across ages (r = .22 for tactile over-responsivity and r = .11 for auditory over-responsivity), but symptoms were more stable among children born prematurely or who had more fearful and less soothable temperaments. A clear implication is that assessment over development may be necessary for a valid sensory processing disorder diagnosis”.
26. Khalsa SS, Adolphs R, Cameron OG, et al. Interoception and mental health: a roadmap. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. 2018;3(6):501–513. PMID 29884281. Checked October 11, 2026.
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    “Interoception refers to the process by which the nervous system senses, interprets, and integrates signals originating from within the body, providing a moment-by-moment mapping of the body’s internal landscape across conscious and unconscious levels.” “Dysfunction of interoception is increasingly recognized as an important component of different mental health conditions, including anxiety disorders, mood disorders, eating disorders, addictive disorders, and somatic symptom disorders.”
27. DuBois D, Ameis SH, Lai MC, Casanova MF, Desarkar P. Interoception in autism spectrum disorder: a review. International Journal of Developmental Neuroscience. 2016;52:104–111. PMID 27269967. Checked October 11, 2026.
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    The abstract: “Interoception ... is atypical in ASD, but the degree and directionality of this abnormality is not yet clear due to the heterogeneity of the condition. Between-group interoceptive differences in individuals with and without ASD have been repeatedly demonstrated, with a slight tendency towards hyporeactivity in interoceptive awareness in individuals with ASD.”
28. Ahn RR, Miller LJ, Milberger S, McIntosh DN. Prevalence of parents’ perceptions of sensory processing disorders among kindergarten children. American Journal of Occupational Therapy. 2004;58(3):287–293. PMID 15202626. Checked October 11, 2026.
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    The abstract: of 703 surveys returned in one suburban U.S. district, “96 children (13.7% of 703) met criteria for sensory processing disorders based upon parental perceptions”; the cautious estimate “suggests that based on parents’ perceptions, 5.3% (96 of 1796) of the kindergarten enrollment met screening criteria for sensory processing disorders.”
29. STAR Institute for Sensory Processing. Symptoms Checklist. Sensoryhealth.org, undated. Checked October 11, 2026.
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    “Many of the symptoms listed in the following categories are common to that particular age group. Where more than a few symptoms are found in a child, we recommend you talk to your doctor”. The infant and toddler list: “My infant/toddler has problems eating”; “has trouble falling asleep or staying asleep”; “is extremely irritable when I dress him/her; seems to be uncomfortable in clothes”; “rarely plays with toys, especially those requiring dexterity”; “has difficulty shifting focus from one object/activity to another”; “does not notice pain or is slow to respond when hurt”; “resists cuddling, arches back away from the person holding him”; “can not calm self by sucking on a pacifier, looking at toys, or listening to my voice”; “has a ‘floppy’ body, bumps into things and has poor balance”; “is easily startled”; “is extremely active and is constantly moving body/limbs or runs endlessly”; “seems to be delayed in crawling, standing, walking or running.” The preschool list includes “My child has difficulty being toilet trained”, “is highly sensitive to stimulation, has big reactions to / does not like touch, noise, smells, etc.”, “is unaware of being touched/bumped unless done with extreme force/intensity”, “has difficulty learning and/or avoids performing fine motor tasks such as using crayons and fasteners on clothing”, “seems unsure how to move his/her body in space, is clumsy and awkward”, “is in constant motion”, “gets in everyone else’s space and/or touches everything around him”, “is intense, demanding or hard to calm and has difficulty with transitions” and “has sudden mood changes and meltdowns that are unexpected”; the school-age list, “My child craves rough housing, tackling/wrestling games”. “While this checklist cannot diagnose Sensory Processing Disorder, it can be a helpful guide to see if additional testing should be done. When filling out this checklist, think about the person’s behavior during the past six months.”
30. Zimmer M, Desch L; Section on Complementary and Integrative Medicine; Council on Children with Disabilities; American Academy of Pediatrics. Sensory integration therapies for children with developmental and behavioral disorders. Pediatrics. 2012;129(6):1186–1189. PMID 22641765. Checked October 11, 2026.
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    The policy statement: “Because there is no universally accepted framework for diagnosis, sensory processing disorder generally should not be diagnosed. Other developmental and behavioral disorders must always be considered, and a thorough evaluation should be completed. Difficulty tolerating or processing sensory information is a characteristic that may be seen in many developmental behavioral disorders, including autism spectrum disorders, attention-deficit/hyperactivity disorder, developmental coordination disorders, and childhood anxiety disorders. Occupational therapy with the use of sensory-based therapies may be acceptable as one of the components of a comprehensive treatment plan. However, parents should be informed that the amount of research regarding the effectiveness of sensory integration therapy is limited and inconclusive. Important roles for pediatricians and other clinicians may include discussing these limitations with parents, talking with families about a trial period of sensory integration therapy, and teaching families how to evaluate the effectiveness of a therapy.”
31. ZERO TO THREE. Numerical Codes for DC:0–5. PDF, undated. The Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood (DC:0–5) “was published by ZERO TO THREE in 2016”. The code list includes “20 Sensory Processing Disorders”: “20.1 Sensory Over-Responsivity Disorder”, “20.2 Sensory Under-Responsivity Disorder” and “20.3 Other Sensory Processing Disorder”. Checked October 11, 2026.
32. Schoen SA, Lane SJ, Mailloux Z, May-Benson T, Parham LD, Smith Roley S, Schaaf RC. A systematic review of Ayres Sensory Integration intervention for children with autism. Autism Research. 2019;12(1):6–19. PMID 30548827. Checked October 11, 2026.
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    “Two randomized controlled trials respectively met 100% and 85% of the CEC criteria items. One additional study met more than 50% of the criteria. Based on CEC criteria, ASI can be considered an evidence-based practice for children with autism ages 4–12 years old.”
33. Acuna C, Gallegos-Berrios S, Barfoot J, Meredith P, Hill J. Ayres Sensory Integration with children ages 0 to 12: a systematic review of randomized controlled trials. American Journal of Occupational Therapy. 2025;79(3):7903205180. PMID 40193295. Checked October 11, 2026.
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    The abstract: “Nine RCTs (N = 344 participants), six with autistic children and three with other child populations, were included”; “Strong evidence from five RCTs (four Level 1b) indicates that ASI supports autistic children in meeting their individualized goals. Moderate evidence from three RCTs (two Level 1b) indicates no benefits of ASI for behaviors of concern, such as noncompliance or irritability”; “More research is needed to determine ASI’s benefits for other child populations.”
34. Piller A, McHugh Conlin J, Glennon TJ, Andelin L, Auld-Wright K, Teng K, Tarver T. Systematic review of sensory-based interventions for children and youth (2015–2024). Frontiers in Pediatrics. 2025;13:1720179. PMID 41321460. Checked October 11, 2026.
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    “Twenty-one studies were included. Strong strength of evidence supported use of deep pressure tactile input and caregiver training on the use of sensory strategies. Moderate strength of evidence supported that alternative seating did not improve attention. Additionally moderate strength of evidence supported targeting a variety of sensory systems is more effective than targeting only one system. There is a lack of evidence on the impact of sensory environmental modifications.” “A third Level II (38) SSD study using sensory diets as part of the regular school day showed three of four participants improving behavior. While results were varied, each participant showed significant improvement in at least one phase of the intervention.” “Overall, the result of this systematic review supports the use of caregiver training to implement sensory strategies across populations of children with SI/SP challenges.”

Medical disclaimer. This page is for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your child.