Someone I know was posting a bunch of common cognitive biases recently, and described something called the Outgroup Homogeneity Bias. Wikipedia says, “According to the outgroup homogeneity bias, individuals see members of their own group as being relatively more varied than members of other groups.”
This of course can be applied to all kinds of things. Right now I want to quote a few people, though. Keep in mind, the groups don’t even have to objectively exist, this stuff also applies to perceived grouping, is in fact possibly an artifact of perceived grouping.
Here is what Stephen Shore says about which autistic people he believes to be mostly alike, and which autistic people he believes show more variation:
The high-functioning Asperger portion of this syndrome has the greatest diversity in shapes because the variation in presentation along with the number of people with autism in this area is the greatest.
This is accompanied by a graph, as shown on this page (scroll down to the part called “The Autism Spectrum”). It shows an arrow saying “increasing variability of presentation”, where the “most variable” people (“HFA/AS”) are supposedly the “least autistic” people, and the “Kanner’s” people are more alike.
Then you have the exact opposite, as stated by Donna Williams:
As a consultant in the field of Autism for the last ten years I have seen many people diagnosed at both the Autistic and Asperger’s end of the spectrum. I have found that Aspies are a far more homegenous group than those with Autism.
Stephen Shore views himself as on the extreme “HFA/AS” end of the autistic spectrum. Donna Williams views herself as part of the “autistic” end of the spectrum. Stephen shore views “Kanner autistics” as more homogenous. Donna Williams views “aspies” as more homogenous.
And many autistic people seem to view non-autistic people as more or less homogenous, and vice versa. And, as I said, this applies to many other things. Sometimes, when you see a group of people (a real one or one you imagine) in your head, as all being the same, it’s because you don’t view yourself as one of that group of people, and you’re falling into that kind of bias.