Imagine you walk into a dodgy diner…the sulphurous smell of onions hits you as you open the door, you start sweating because there is no air conditioning, and the more you sweat the worse the chaffing of your too-tight collar gets. You jump, startled as deafening music starts up suddenly, it feels like the drum beat is pulsating in your ears. You can feel your anxiety building, you start blinking in rhythm to the flickering fluorescent lights…you want to take flight, or at the very least fight the assault on your senses.
Exaggerated? Yes, but children with sensory defensiveness may want us to experience the overwhelming world they live in just once. These kids act with alarm when confronted by sensory input which seems harmless to others. Innocent or seemingly neutral stimuli will drive these children to exaggerated responses—welcome to the world of sensory defensiveness.
What is sensory defensiveness?
Sensory defensiveness is a sensory modulation disorder which falls under the umbrella of sensory processing disorders (SPD). Sensory defensiveness is a group of symptoms occurring as a result of a defensive or (over) reaction to neutral or even positive stimuli.
More specifically, one of the earliest definitions of sensory defensiveness, explains: “The tendency to react negatively or with alarm to sensory input that is generally considered harmless or non-irritating is typical of sensory defensiveness. Common symptoms may include oversensitivity to light, unexpected touch, and sudden movement, or overreaction to unstable surfaces, high-frequency noises, excessive noise or visual stimuli, and certain smells.” (Wilbarger & Wilbarger, 1991).
The world is an overwhelming place for a child whose senses react in this way to everyday or neutral stimuli. Their sensory defensiveness will cause them to react to such input with negative behavior and emotions. They may even avoid daily routines to protect (or defend) themselves and this could lead to delays in reaching developmental milestones.
Different types of sensory defensiveness
Sensory defensiveness can be observed in any, or sometimes all, of the sensory systems. The child will try to defend him or herself against the offensive (or so perceived) sensory stimulus by avoiding it, minimizing exposure, or by displaying certain behaviors or emotions like irritation, frustration, or aggression.
Defensiveness in the following sensory systems is identifiable by the corresponding behavior:
Auditory defensiveness is characterized by an extreme sensitivity to sound. The child’s nervous system may interpret sounds as too loud, or the pitch may be intolerable. To deal with the discomfort, the child may act out, try and avoid or minimize the auditory input, hyper-focus on something else, or escape. The following behaviors may be observed in children with auditory defensiveness:
- They may show extreme sensitivity to everyday sounds like the vacuum cleaner or hairdryer. Often a child experiencing such sensitivity or defensiveness will cover his/her ears, or appear anxious and tense in a noisy environment
- They may not like activities or environments usually loved by kids. Birthday parties, kid-centred restaurants, and indoor playgrounds may be too loud and overwhelming for them
It is usually not difficult to spot visual defensiveness in a child; he/she will squint and get very uncomfortable in bright light, prefer to be indoors when the sun is shining, and get disorientated if an environment is visually overwhelming. For some kids, visual defensiveness manifests in the following manner:
- A camera’s flash will leave their eyes watery and sore
- They insist on wearing sunglasses whenever they step outside
- They may get nauseous looking at vast moving, bright objects like a roller coaster or merry-go-round
- Some of these children actually feel their eyes burn when they have to maintain eye gaze (or contact)—the link between autism and sensory defensiveness may find relevance in such examples, but more on this later
In this category defensiveness of the olfactory (sense of smell) and gustatory (sense of taste) systems are often included. Some treat oral defensiveness as a separate category, focusing purely on defensiveness exhibited in reaction to touch of the mouth (for example a stress response to touch of the lips to apply ointment, brushing of teeth or visiting the dentist), or anything being put in the mouth, like medication or food. In general children with oral, taste and smell defensiveness will:
- Have extreme reactions and an aversion to oral hygiene. For some parents brushing their child’s teeth ends in tears (or worse!) on a daily basis
- Be very particular about food texture, either everything crunchy or soft and mushy. A mixture of textures is usually not tolerated at all, this may be apparent when the child gags when introducing baby food with lumps or small pieces of vegetables
- Sensitivities may extend to spiciness, and the smell of spices. Usually bland food is preferred
Vestibular, gravitational or postural insecurity
The vestibular system contributes to balance, functions to detect head motion and position, and provides important messages and information to the brain about the location of the body in relation to its surroundings. A child with vestibular insecurity may:
- Show an adverse reaction to having their head tipped, moved or manipulated (at the dentist, or hairdresser)
- Prefer sedentary activities. The child may not enjoy bike riding or swinging as their feet are off the ground and their balance issues may create anxiety
When referring to sensory defensiveness, tactile defensiveness is probably the most well known and most studied area of sensory defensiveness. Dr. Jean Ayers was an occupational therapist who first identified tactile defensiveness in children in 1964 (Ayers, 1964). A child with tactile defensiveness will over respond to touch, or as Dr. Ayers explained, he/she may have a negative reaction or avoidance of non-noxious tactile stimuli (Ayers, 1964). Tactile defensiveness may manifest in some of these behaviors:
- Avoidance of light touch, but actually seeking out deep touch
- May show strong preference for certain types of clothing, will be bothered by clothing labels, shoes and many other things which other children don’t seem to notice
- Does not like to get hands dirty, or the feel of specific play materials like putty
- May avoid walking on surfaces like grass or a specific type of carpet
Defensiveness in any or all of these sensory areas may lead to behavior of avoidance or acting out. Sensory defensiveness is misunderstood and, because it is not recognized as an official medical diagnosis, these children are often described as out of control—when in fact their brain is telling them their world is out of control and they’re merely reacting to that message!
Sensory defensiveness and autism
Many published studies have confirmed the high percentage of autistic children who also have sensory difficulties and disorders. A study by Tomchek and Dunn (2007) found that 95% of the sample of children with autism spectrum disorder (ASD) showed some degree of sensory processing difficulty.
In the DSM-5 (5th ed.;DSM-5, American Psychiatric Association, 2013) criteria for autism spectrum disorders, atypical sensory behaviors are listed as a possible symptom of restricted, repetitive patterns of behavior, interests or activities.
Taking the odds into consideration, your austistic child is very likely to have sensory difficulties or sensitivities and this may well be sensory defensiveness. It is very important to keep this in mind, as the knowledge may prepare parents for situations that could potentially overwhelm their children with autism.
A study by Spira and Kupietsky (2005) looked at oral defensiveness in children with dysfunctional sensory regulation. Principles discussed were applied to a dentist appointment. Going to the dentist is not a treat for many or any of us, but the details of the study gives an idea of just how traumatic it must be for a child with sensory defensiveness.
From the authors’ suggestions of how to make the child comfortable (Spira & Kupietsky, 2005) the following becomes apparent:
- The child will be entering a place with bright lights, many unfamiliar people, noise from dental apparatus and various chemical smells. In this regard, suggestions of keeping the environment similar and offering choices is discussed
- The child will have his/her face and mouth touched, possibly alerting their tactile and oral defensiveness. He/she may also have to tip their head back and sit on a reclining chair with their feet off the ground—which is tough on vestibular insecurity
- Most traumatically, a loud suction machine will be inserted in their mouth, possibly activating not only oral but also auditory defensiveness
Imagine your autistic child dealing with the social challenges of visiting the dentist; and then add all these sensory defensiveness challenges to the appointment—no wonder the authors say the dental environment may be a “source of great difficulty for the child and parents.” Their suggestions of making the child comfortable rely on the pediatric dentist being educated about the challenges faced by a child with oral defensiveness.
In a presentation (Supporting Nervous System Function Through Sensory Intervention and Adaptation) for the Autism Parenting Summit, author and behavioral therapist Rebecca Duvall Scott and occupational therapist Hannah Ragan shared some advice for parents dealing with sensory difficulties.
Rebecca detailed the story of her son’s journey with sensory processing disorder, and along with Hannah, shared many practical tips to help children with sensory difficulties thrive.
Some of these suggestions include:
- A sensory diet: Sometimes a child will need to eliminate elements like gluten and diary. The child may also need to be tested for deficiencies and his/her diet may need to be supplemented to enable optimum functioning of the nervous system
- Occupational therapy and speech therapy: Work with a team that understands your child’s condition and specific sensory difficulties
- Environmental adaptations are often needed to make certain experiences sensory-friendly: Practical examples like taking noise cancelling headphones to loud places, or providing deep pressure with weighted blankets during times of stress are discussed
- Above all, parents should be aware of their child’s triggers: They can then make the child aware of these and help him/her become sensory-smart. The presenters make a great case for a child who is aware of (and understands) their own sensory needs. Such a child is able to advocate for him/herself, control his/her environment better, and ultimately make better decisions (about things like future career etc.) as they recognize their strengths and sensory limitations
Rebecca and Hannah wrote a book with treatment strategies and insights for parents helping their kids deal with sensory differences: Sensational Kids, Sensational Families: Hope for Sensory Processing Differences.
Research is only starting to change people’s perceptions about sensory difficulties. For too long many in the medical community refused to acknowledge SPD and other sensory challenges. For children with autism—who may already be fighting an uphill battle dealing with daily social and communication challenges—sensory defensiveness makes the world an overwhelming place.
Parents who educate themselves, advocate for their children, and who try to make their child’s environment just a little less scary and overwhelming, are making a huge difference. Your autistic child with sensory defensiveness is probably really tired of fighting a battle the world is oblivious to.
American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013.
Ayres AJ (1964). Tactile functions: their relation to hyperactive and perceptual motor behav- ior. American Journal of Occupational Therapy 18: 6–11.
Scott, R.D., Ragan, H. (2020) Sensational Kids, Sensational Families: Hope for Sensory Processing Differences. Silver Linings Media.
Scott, R.D., Ragan, H. (Supporting Nervous System Function Through Sensory Intervention and Adaptation) Autism Parenting Summit, April 2021
Spira, Geela & Kupietzky, Ari. (2005). Oral defensiveness: Children with a dysfunction of sensory regulation. The Journal of clinical pediatric dentistry. 29. 119-22. 10.17796/jcpd.29.2.cgp2830l073vh358.
Wilbarger, P., & Wilbarger, J.L. (1991). Sensory defensiveness in children aged 2-12. Santa Barbara, CA: Avanti Educational Programs.