Sensory Life.
One of the most common experiences in Autism is that of sensory differences. It’s taken a lot of talking to get professionals to listen, but sensory differences have been included in the DSM (diagnostic manual) since 2013. These sensory differences are a spiky profile: people have a mix of sensory seeking and sensory avoidant behaviours, and heightened or reduced sensitivity – often all in the same person – and there are a lot of hypotheses as to why this is true, but no clarity.
Studies exploring these sensory differences find that Autistic children have a significant difference in sensory experience to allistic children, to the point that sensory profiles have a degree of usefulness in the diagnosis of Autism. Even more interestingly, there is no strong correlation between severity of sensory processing issues (measured in the studies) and researcher-defined severity of Autism. So in other words, if you’re Autistic, you’re extremely likely to have sensory differences, and that doesn’t change if people perceive you as ‘more’ or ‘less’ Autistic than others.
Apart from the five senses everyone is aware of, there are other senses that can also be different from typical in the Autist.
– interoception, or the awareness of what’s going on inside your body (hunger and thirst, for example, or changes to the internal organs)
– proprioception, or the awareness of where your body is in space, which is sometimes separated from the vestibular sense, sometimes called equilibrioception (important for balance and smooth movement)
– thermoception (temperature awareness),
– nocioception (pain awareness)
One interesting theory as to why our sensory experience is different is that of ‘low latent inhibition’. Latent inhibition describes the way brains can filter out sensory input that it considers ‘unimportant’. Some people – including most people on the Spectrum – have less restrictive filters, meaning that sound, smell, lighting, movement etc does not get labelled ‘unimportant’, and therefore doesn’t get filtered out.
This theory has several potentially important consequences. First, it means that in processing ‘social and reciprocal interaction ‘, we are always concurrently processing a shite-load of other information from our environment, meaning that our minds aren’t ever fully focussed on social cues and conversation. Second, it means that when input is too complex or strong, sensory overload is likely. Finally, it appears to have implications for stress and responses under stress. When your brain doesn’t categorise anything as ‘unimportant’, you spend your whole day in something of a state of heightened expectation. Every task is achieved by working through a sense of urgency which most people wouldn’t be aware of. This in turn suggests that in a real emergency situation, there is less difference from the norm in the level of stress for someone with low latent inhibition than there would be for someone without it, and emergency situations are processed in more or less the same way as everyday situations.
While this is only hypothetical, there is much anecdotal evidence for Autistic adults being clearer and more in control during an emergency than allistic adults.
There are other theories also, including ones which consider increased numbers of and connectivity between neurons, or ‘atypical lateralisation’ of nerve impulses (i.e. things shoot off sideways instead of sticking to the main path).
We often say that Autism affects all of us; every single aspect of our lives and experiences is processed through an Autistic filter. When you consider that over 80% of the nervous system (including the brain) is involved in processing or organising/responding to sensory input, you start to realise what that means.
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Even before I knew enough about Autism to realise sensory sensitivity was an aspect of it – let alone that I was Autistic – I knew I had sensory issues.
All of being a picky eater for me was about the sensory aspect of eating. This is something I’ve always thought was fairly normal, because my family are the same. My mother, my auntie and I were having lunch in a cafe once, and had all ordered lemon tart for dessert. Together, we each had one mouthful, and together, we each spat that mouthful out into the napkin. Someone had cut the tart with a knife that had previously cut onions. Some foods taste bitter to me, but not to others. Some foods burn – not because they are hot, either temperature-wise or spicy – but because something in that food affects my mouth and burns me. Tomato, most melons, bananas and pineapple all make my mouth itch. Textures are also a dietary issue. Growing up, pumpkin and mushrooms were so slimy that they made me gag (mushrooms still do). It felt like someone was wiping sludge on the back of my tongue.
Every now and then, my light sensitivity gets out of control, and I have what I call a ‘light attack’. Suddenly, everything is too bright and glary, and I can’t keep my eyes open. It can come on suddenly – it has come on when I was driving – and for a few minutes it is the single most powerful force in my life.
I have a couple of photos of me in kindergarten, 4 years old. The kindergarten children were to be on a float for the New Year’s Eve parade, and I was to be a mermaid.
Mum had made a tail out of material, and sewn aluminium foil scales onto it, and I put it on and went outside to have my photo taken. I remember how, suddenly, the brightness completely overwhelmed me and the photos show this, too.
It isn’t a migraine. I’ve had migraines, both painful and ‘silent’ – that is, with the visual disturbance, light sensitivity and odd tingling in my face, but without the pain – and it doesn’t feel like that at all; it’s absolutely about my eyes suddenly not being able to bear so much light.
My sound sensitivity seems to be getting worse with age. I am now much more intolerant of noises around me, and have one heck of a startle reflex when I get woken from sleep. I find it difficult to ignore things like electric fans, traffic or computer whine (the high pitched noise that sits just between sound and someone scraping your nerve with a rusty blade). Touch is something I crave – I love stroking certain fabrics and textures, and love deep, firm hugs and weight on me while I sleep. Light, feathery touch, however, is agitating and makes me twitchy and irritated. And my sense of smell – I get headaches from all but a very few perfumes, even when they’re not on strongly. I have one brand of shampoo and two body washes I can use, and use unscented products whenever I can. I can smell smoke on a jacket for several days after I’ve been around someone who smokes, even if we were outside.
Sensitivities are increased when I’m anxious or unwell, but they’re not always bad or uncomfortable. Synaesthesia, the crossing-over of more than one sense (most powerfully, music and colour, but to a lesser degree, colour with numbers, letters and days of the week), remains one of the most precious things in my life.
The beauty found in the minutiae of objects is awe-inspiring, the unravelling of tastes, instrumental lines in orchestral music, and the transmission of comfort through an unmoving touch – all exquisite. And yet the psychological and medical literature focusses so heavily on the negative aspects, and the suppression and ‘treatment’ of these sensory differences. I suspect most of us would like to learn to filter the extraneous input, but not if that means dulling everything else.
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