Autism is called a spectrum disorder not because it ranges on a smooth continuum from "no autism" to "lots of autism".

It's because there a handful of associated symptoms for autism and different people have a different mixture of them. You don't need an equally large amount of all symptoms in order to be autistic.

Think of it more like a light spectrum where there are different mixtures of hues for the symptoms, but autism still implies some amount of significant overall intensity. In short, it's a spectrum, not a continuum.

If you experience some or all of the symptoms associated with autism but at a level that doesn't significantly impair your overall functioning, then that's not a diagnosis of autism. Just like everyone who gets sad isn't depressed and everyone who worries doesn't have generalized anxiety. That's just normal human variability and life challenges.

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waterhouse a day ago | parent [-]

I have encountered this definition of "spectrum", as a vector of numbers that go 0 to 100, rather than a single number that goes from 0 to 100 (which you call "continuum" IIUC).

But... I mean, if you asked 100 people what they think a spectrum means in this context, how many of them would think it meant "vector" rather than "real number"? I would guess fewer than 10. I consider myself a fairly well-informed nerd, but I think I had encountered many usages of "spectrum" describing a single trait for many years, and I think this is the second time I've ever encountered someone using the "vector" definition (the first one was also using it to describe autism). Has this linguistic battle already been lost? Does it improve clarity to call it a "spectrum" and insist on using the "vector" definition?

(I've personally been using the phrase "collection of imperfectly correlated traits")

	▲	sctb a day ago \| parent \| next [-]
		I think the word "spectrum" is reasonable, as it implies a broad range. Or it's analogous to the rainbow with a variety of colours. But what people consistently misunderstand is that there is a fundamental dichotomy at the diagnostic level. Speaking from the perspective of the DSM, which I prefer because it's at least concrete and has medical relevance in North America, you meet the criteria for Autism Spectrum Disorder ("on the spectrum") or you do not ("not on the spectrum"). In other words, the diagnostic criteria themselves do not constitute a spectrum, especially not a linear one. Maybe people are confusing this with the DSM's three levels of support needs.
	▲	munificent a day ago \| parent \| prev [-]
		I agree, the terminology is confusing. It is extra confusing because the intent is to capture both: 1. Different autistic people may vary in which symptoms are most severe while all still being autistic. 2. Different autistic people may vary in the overall severity of all symptoms and how much it impacts their quality of life. (At the same time, there is still a distinct cut off where you are not considered to have autism if it doesn't manifest significantly in your life.) The latter point is why "Asperger's" is now simply lumped in with ASD. But that tends to obscure the former point which is also important. Perhaps "cluster" would have been better, but here we are.