For autistic people, while their sensory systems function perfectly well, it is the processing of the sensory information coming into their brain that can cause difficulty. This applies to the sensory impressions they receive from their external environment as well as to the internal signals that are generated in their body, including emotional sensations as well as messages from their nerves, muscles and joints.
When problems occur with the processing of sensory information, unprocessed sensory data can start to accumulate in the brain. This happens differently for each autistic person, depending on which of their senses are affected. People may experience hyper- or over-sensitivity in their visual system but their other sensory systems may be unaffected, or they may experience over- or under-sensitivity in more than one sensory system. If too many images, sounds and sensations stack up waiting to be processed, the person’s brain may interpret this sensory overload as threatening, to the point where it triggers the body’s self-defence system.
In order to protect themselves, the autistic person may retreat into repetitive behaviours, defending themselves from distressing sensory data coming into their brain. By doing this, the person is able to focus on something that makes sense to them and that requires little or no processing in their brain. If the person cannot achieve coherence in this way, there is a risk they may experience sensory overload which can be both acutely painful as well as very frightening. The person may lash out at those around them or they may harm themselves. Such behaviour is often misunderstood and seen as willful, whilst in fact it should understood as the person using the most immediate coping mechanism available to them to alleviate the pain, fear and confusion they are experiencing.
Creating an autism-friendly environment
In order to reduce the likelihood of the person’s sensory processing system becoming overloaded and the resulting sensory chaos, we need to scale down those sensory inputs to which the person’s brain is hyper- or over-sensitive and increase those inputs which are easily processed. As the level of stress which the person is experiencing comes down, so the brain seems to function more effectively. It follows, therefore, that it is not possible to comment meaningfully on whether or not a person has learning disabilities or on the extent of any such disabilities without first having investigated that person’s sensory processing difficulties.
Strategies for reducing sensory distress caused by visual and auditory hypersensitivity. Although not every individual will respond positively, it is always worth exploring these options.
Visual hypersensitivity can be alleviated by wearing Irlen lenses, prescribed by a certified Irlen Screener (see here). If the person is not comfortable wearing Irlen lenses, the use of coloured light bulbs may reduce their visual distress. The Irlen Screener can advise on which colour bulbs will be most effective.
Some children and adults with auditory hypersensitivity are helped by noise cancelling headphones. Designed for use by pilots, these headphones cancel out background noise with the result that the person is able to process close up conversation. Noise cancelling headphones can be very effective in helping autistic people to cope with noisy environments such as school, supermarkets and busy city centres. Phoebe Caldwell has had very good results using Bose Quiet Comfort noise cancelling headphones with the people she supports.