I have stolen the below information from the most fantastic organisation called The National Autistic Society. I sometimes find things hard to explain, even though I live with the affects every day. I have reduced it a bit as it was a very long article but if you want to read the complete thing, just visit http://www.autism.org.uk/sensory
Many people with an ASD have difficulty processing everyday sensory information such as sounds, sights and smells. This is usually called having sensory integration difficulties, or sensory sensitivity. It can have a profound effect on a person’s life.
How our senses work
Our central nervous system (brain) processes all the sensory information we receive and helps us to organise, prioritise and understand the information. We then respond through thoughts, feelings, motor responses (behaviour) or a combination of these.
We have receptors all over our bodies that pick up sensory information, or ‘stimuli’. Our hands and feet contain the most receptors. Most of the time, we process sensory information automatically, without needing to think about it much.
People with sensory integration difficulties – including many people with an ASD – have difficulty processing everyday sensory information.
People who struggle to deal with all this information are likely to become stressed or anxious, and possibly feel physical pain. This can result in challenging behaviour.
Our seven senses
We have seven senses:
- balance (‘vestibular’)
- body awareness (‘proprioception’).
People with an ASD can be over- or under-sensitive in any or all of these areas. You may hear this referred to as being ‘hypersensitive’ or ‘hyposensitive’.
Situated in the retina of the eye and activated by light, our sight helps us to define objects, people, colours, contrast and spatial boundaries. People with an ASD may experience the following differences.
- Objects appear quite dark, or lose some of their features.
- Central vision is blurred but peripheral vision quite sharp.
- A central object is magnified but things on the periphery are blurred.
- Poor depth perception; problems with throwing and catching; clumsiness.
- Distorted vision: objects and bright lights can appear to jump around.
- Images may fragment.
- Easier and more pleasurable to focus on a detail rather than the whole object.
This is the most commonly recognised form of sensory impairment. Hearing impairments can affect someone’s ability to communicate and possibly also their balance. People with an ASD may experience the following differences.
- May only hear sounds in one ear, the other ear having only partial hearing or none at all.
- May not acknowledge particular sounds.
- Might enjoy crowded, noisy places or bang doors and objects.
- Noise can be magnified and sounds become distorted and muddled.
- Particularly sensitive to sound and can, for example hear conversations in the distance.
- Inability to cut out sounds – notably background noise, which often leads to difficulties concentrating.
Touch is important for social development. It helps us to assess the environment we are in (is an object hot or cold?) and react accordingly. It also allows us to feel pain. People with an ASD may experience the following differences.
- Holds others tightly – needs to do so before there is a sensation of having applied any pressure.
- Has a high pain threshold.
- May self-harm.
- Enjoys heavy objects (eg, weighted blankets) on top of them.
- Touch can be painful and uncomfortable; people may not like to be touched and this can affect their relationships with others.
- Dislikes having anything on hands or feet.
- Difficulties brushing and washing hair because head is sensitive.
- Only likes certain types of clothing or textures.
Chemical receptors in the tongue tell us about different tastes – sweet, sour, spicy and so on. People with an ASD may experience the following differences.
- Likes very spicy foods.
- Eats everything – soil, grass, Play-dough.
- Finds some flavours and foods too strong and overpowering because of very sensitive taste buds. This can result in a very restricted diet.
- Certain textures cause discomfort; some children will only eat smooth foods like mashed potatoes or ice-cream.
Chemical receptors in the nose tell us about smells in our immediate environment. Smell is the first sense we rely upon. People with an ASD may experience the following differences.
- Some people have no sense of smell and fail to notice extreme odours (this can include their own body odour).
- Some people may lick things to get a better sense of what they are.
- Smells can be intense and overpowering.
- Dislikes people with distinctive perfumes, shampoos, etc.
Situated in the inner ear, our vestibular system helps us maintain our balance and posture, and understand where and how fast our bodies are moving. People with an ASD may experience the following differences.
- A need to rock, swing or spin to get some sensory input.
- Difficulties with activities like sport, where we need to control our movements.
- Difficulties stopping quickly or during an activity.
- Car sickness.
- Difficulties with activities where the head is not upright or feet are off the ground.
Body awareness (proprioception)
Situated in the muscles and joints, our body awareness system tells us where our bodies are in space, and how different body parts are moving. People with an ASD may experience the following differences.
- Stands too close to others, because they cannot measure their proximity to other people and judge personal space.
- Hard to navigate rooms and avoid obstructions.
- May bump into people.
- Difficulties with fine motor skills: manipulating small objects like buttons or shoe laces.
- Moves whole body to look at something.
Synaesthesia is a rare condition which some people with an ASD experience. A sensory experience goes in through one system and out through another. So a person might hear a sound but experience it as a colour. In other words, they will ‘hear’ the colour blue.
How sensory sensitivity can affect behaviour
Sometimes, a person with an ASD may behave in a way that you wouldn’t immediately link to sensory sensitivities – but they may be the underlying cause. Here are a few some examples of how a person’s behaviour may result from sensory sensitivities.
- Possible reasons: sensitive to taste or texture, or unable to feel food around the mouth.
chews on everything, including clothing and objects
- Possible reasons: may find this relaxing, or enjoy the sensation of chewing on the item.
refuses to wear certain clothes
- Possible reasons: may dislike the texture or pressure of clothes on their skin.
difficulties getting to sleep
- Possible reasons: may have difficulty shutting down their senses, in particular sight and hearing.
finds it difficult to concentrate in the classroom
- Possible reasons: too many distractions like noise (talking, bells, chairs scraping the floor) or visual stimuli (people, pictures on the wall). May also find holding a pencil uncomfortable (it may feel hard or cold).