Autism and Sensory Processing

What is Sensory Processing?

Sensory processing is our ability to combine and understand information coming in from our senses. Our brain continuously receives information from all of our senses. Our brain then filters through this information in order to decide which information is important to attend to and which isn’t. Sensory processing is an automatic process. The purpose of this process is to enable us to be able to attend, organise and move our bodies and manage our emotions as efficiently as possible. Autism can cause a more varied experience of sensory processing.

Within the DSM-5 criteria for Autism, sensory processing differences known as hypo or hyper sensitivity are categorised under section B “restrictive, repetitive patterns of behaviour”.  Whilst this does reference the sensory processing difficulties somewhat in terms of engaging in self-regulatory behaviours/’stimming’ it doesn’t necessarily reflect the impact that sensory processing difficulties can have on an autistic individual’s participation in everyday activities. One of the most commonly reported explanation that autistic individuals give for having difficulty participating in everyday activities, school life or social situations are sensory processing difficulties/sensitivities and difficulty tolerating the sensory aspect of an environment.   

It is common for autistic individuals to report difficulty tolerating every day sensations such as smells, background noise, or the sensation of clothes. We think autistic individuals may not have the same ability to filter through and get used to the information the brain is receiving. If this filtering isn’t happening efficiently, the brain can be flooded with sensory information which can make it difficult for the person to attend to other things in the environment (e.g. someone talking to them) and can be overwhelming emotionally too. 

What are our senses and what do they control?

Most people will know our five basic senses – vision, hearing, smell, taste and touch. However, there are 3 other less known senses – the vestibular sense, proprioception and interoception. As mentioned in previous pages, it’s best to think of autism in the social model of disability. This means considering how the environment is disabling to an autistic individual. Autistic people may be described as having sensory issues, but sensory differences is more accurate in describing the variety of ways our community processes the environment around us.

What is Sensory Overload and why is it so common with Autism?

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Sensory overload can be distressing for autistic people

The purpose of our sensory processing is to keep us calm but alert in relation to what is going on in our environment. If individuals are not able to filter through the sensory information in their environment it can be more difficult to remain calm or alert. This build up of sensory information is referred to as sensory overload. This can feel different for different people. An individual experiencing sensory overload may become irritable, anxious, upset or even completely shut down in their attempt to regulate their sensory environment. While sensory overload is not exclusive to Autism, it is experienced more acutely by autistic people.

Our bodies have a number of automatic reactions that occur when faced with a potentially threatening or dangerous situation. These reactions are called our ‘fight or flight’ reaction and are built into our bodies to enable us to escape quickly should that be necessary. Part of this ‘fight or flight’ reaction is that our senses become heightened or more sensitive.

This begins with our ear drums changing shape to allow in lower frequency sounds that we would usually filter out.  Our eyes also become more alert and also scan the environment more frequently and rapidly. At a physiological level, our heart might begin to race, and our breathing might become quicker which pumps oxygen to our muscles so we are ready to run. Sometimes however, the ‘threat’ is not a physical one i.e. we are not actually in physical danger, rather we experience a psychological stress such as receiving unexpected bad news, having an exam or test or a falling out with a friend. But the reaction in our body can be the same .

 Alongside the emotional upset, we will become more sensitive to sensation. For example, if we are feeling stressed and someone touches us we may jump because we have become more sensitive to sensory input. This in turn can make us more emotionally upset so it can become a cycle of sensory sensitivity and stress. For autistic individuals who tend to be naturally more sensitive to sensory input, minimising other stressors in the environment or routine is as important as sensory calming activities in preventing sensory overload.  

What is Self Regulation?

Self-regulation is something that we all do in one way or another. It refers to using activities or behaviours to maintain a calm and alert state to help us manage the changing demands we experience in our environment. If we feel ourselves becoming anxious, irritated or overwhelmed we may take some deep breaths, have a cup of tea, play with a pet, turn to a hobby such art or writing or take a break from the environment.  Similarly, if we feel ourselves getting distracted, bored or fidgety, we might stretch or go for a walk if possible, fidget, take a cold drink listen to loud music. All these activities could be considered self regulation strategies as they help us to return to a calm and alert state. Although similar, self-regulation is different to a sensory diet in that it is more intuitive i.e. depends on the person noticing when their body needs more or less sensory input rather than a planned schedule of sensory breaks. 

What is Stimming?

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Understanding stimming is crucial to encouraging coping strategies related to autism and sensory processing. Self stimulatory behaviours or “stimming” is a type of self-regulatory behaviour which often involves repetitive behaviours, movements or noises. Stimming may involve something like hopping from one foot to the other, repeating a word or phrase, flapping hands or something more subtle like playing with hair. In the past, stimming used to be something that people were trying to stop, mistaking it for ‘fidgeting.’

We now know that stimming is essential for autistic people to be able to do this. Unfortunately, people who are stimming in public can face judgement or stigma.  It is important to remember that while this behaviour may seem unusual this behaviour is very important to the individual and serves a purpose for them in relation to regulating their emotions, environment and behaviour. It is important that we normalize stimming in schools, workplaces and public spaces to ensure that autistic people are able to regulate themselves and feel self to do so authentically. 

Stimming can happen for a number of reasons. Sometimes it can be a way to express excitement or happiness, but it can also be a sign that the person is feeling overwhelmed and is trying to calm themselves. For example, an autistic person who is experiencing sensory overload may begin stimming to cope with their environment, especially if there is no quiet space available. This means stimming can be a vital mechanism for preventing meltdowns. 

You can learn more about fidget toys or items, which are a vital aid to autistic stimming, in this resource.

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