Research: Perceptual "noise" filters and ASD

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High internal noise and poor external noise filtering characterize perception in autism spectrum disorder
Woon Ju Park, Kimberly B. Schauder, Ruyuan Zhang, Loisa Bennetto & Duje Tadin
Scientific Reports 7, Article number: 17584 (2017)
doi:10.1038/s41598-017-17676-5

An emerging hypothesis postulates that internal noise is a key factor influencing perceptual abilities in autism spectrum disorder (ASD). Given fundamental and inescapable effects of noise on nearly all aspects of neural processing, this could be a critical abnormality with broad implications for perception, behavior, and cognition. However, this proposal has been challenged by both theoretical and empirical studies. A crucial question is whether and how internal noise limits perception in ASD, independently from other sources of perceptual inefficiency, such as the ability to filter out external noise. Here, we separately estimated internal noise and external noise filtering in ASD. In children and adolescents with and without ASD, we computationally modeled individuals’ visual orientation discrimination in the presence of varying levels of external noise. The results revealed increased internal noise and worse external noise filtering in individuals with ASD. For both factors, we also observed high inter-individual variability in ASD, with only the internal noise estimates significantly correlating with severity of ASD symptoms. We provide evidence for reduced perceptual efficiency in ASD that is due to both increased internal noise and worse external noise filtering, while highlighting internal noise as a possible contributing factor to variability in ASD symptoms.


https://www.nature.com/articles/s41598-017-17676-5

Brilliant! published in Nature

For those folks contemplating whether it's worth spending time on WP - if no other reason it's a great resource for reading material

Thanks Darmok!

Alex (or mods) if you are reading this then please (as a suggestion) please create a library of links to reading material like this. A lot of parents are really ignorant of what ASD is...

What the hell is "internal noise"?!

I'm no neurobiologist, but I believe it refers to the normal "static" that occurs during the electrical transmissions in the nervous system -- just like noise in an electrical line. Here's some technical detail -- maybe an expert can explain its relevance to us:

https://en.wikipedia.org/wiki/Neuronal_noise

simple - when people receive input from the environment (auditory, visual, chemosensory etc) the brain processes sensory data to make sense of the information which they use for such things as learning, recognition or responding appropriately to an environmental stimulus

internal noise therefore refers to internal neural activity that interferes with the above processing. This internal noise arises from a multitude of sources at every stage in the process from receiving the environmental stimulus to perception of that stimulus.

The hypothesis is that people with ASD have more internal noise than NTs which over the long term interferes with normal neural development from childhood leading to behavioral and motor symptoms often characterizing ASD as a disorder

Just a philosophical question:
How does one define what is "information" and what is "noise"?
Maybe autism is all about scanning the information that others tend to disregard as "noise"?
And every time an autistic person picks up something important that could not get through the "noise cancelling" devices in NT brains, they say: "Savant! Eccentric genius!"

I doubt my inner noise filtering is working well because I can constantly hear and see the visual snow (the noise I hear is just like thousands of tiny diamonds silently hitting each other in the air). https://en.wikipedia.org/wiki/Visual_snow
I have had it since I remember.

Although that true I become pretty good at ignoring it - I am not aware of it being there all the time although its always there. I see the world as if it was on a screen of an old TV with poor signal, but in HD.

I think Darmok refereed to a crackling in the brain but it it's not that simple. Noise can be any internal activity generated in the brain (i.e. not a response to the environment). For example it can be a visual representation generated in vitro that the person can't control and therefore interferes with normal daily functioning (just one example)

People with Schizophrenia have a "lot" of internal noise (voices/seeing people)

Yes I think NTs are supposed to have better internal noise filters - or so the hypothesis goes

Yeah, I hear a constant hiss in my ears. That's my internal noise.

I was more interested in defining external noise. Our senses are attacked by tons of information from our surroundings all the time. How to tell what of this is valid information and what to disregard as noise? How our brains do it? Do autistic brains to it differently than NT brains? Is this divergence really a bad thing?

Yes I've often heard that autism also means not being able to filter out all sensory input. NT brains are able to filter out and pay attention to specific stimuli whereas with ASD over-stimulation due to certain sensory input can tamper with that filter. But in that case it's not necessarily internal noise but more over-stimulation from the environment

Thanks for posting, Darmok, I found that very interesting. I've always perceived an aural equivalent of my visual snow and migrainey visuals, but I've very rarely seen it written about as being distinct from tinnitus.

My daughter's audiologist refers to it as misophonia, apparently its a processing error in the auditory cortex and occurs in some NTs as well.