For those who have never studied statistics, the non-autistic population in Western countries is said to have an average IQ of 100 and a standard deviation (SD) of 15. A standard deviation of 15 simply means that the standard amount by which most people deviate from the average is around 15 points, in other worlds, about two thirds of the non-autistic population have IQ’s from 85 to 115.
As for the autistic population, a recent study found 16% of autistic spectrum children had IQ’s below 50, while 3% had IQ’s above 115.
Assuming a normal distribution, an IQ of 116+ is 1.87 Standard Deviations (SD) above the autistic mean, and an IQ below 50 is 1 SD below the autistic mean. This suggests that autistic people have a mean IQ of 72 and an SD of 23 compared to the non-autistic population (mean 100, SD=15). In other words, while the average autistic person has a much lower IQ than the average neurotypical, the autistic population is much more cognitively variable. This resolves the paradox of why autistic people can simultaneously have a reputation for being both mentally disabled and brilliant scientists. Because, compared to neurotypicals, autistic people will be dramatically over-represented at both ends of the bell curve.
Above IQ 100
About 50% of neurotypicals have IQ’s above 100, compared to only 10% of autistic people.
Above IQ 115
About 14% of neurotypicals have IQ’s this high, compared to to only 3% of autistic people.
Above IQ 130
About 2% of neurotypicals score this high, compared to only 0.5% of autistic people
Above IQ 145
Only one in 924 neurotypicals score this high, compared to only one in 1,838 autistic people
Above IQ 160
Only about one in 42,000 neuotypicals scores this high, compared to one in 18,000 autistic people. At this level of giftedness, autistic people are actually OVER-REPRESENTED!!!!!!!!!!!
Above IQ 175
Only about one in five million neurotypicals score this high, compared to about one in 300,000 autistic people.
Above IQ 190
Only about one in 1.5 billion neurotypicals score this high, compared to about one in 14 million autistic people.
The fact that autistic people are so incredibly variable in IQ comfirms Pumpkin Person’s groundbreaking theory that autism is not actually one phenotype, but two phenotypes, that have been arbitrarily conflated by psychologists: Nerdiness (slow life history?) which causes high IQ, and executive dysfunction which causes low IQ.
Analogously, schizophrenia is probably also two phenotypes: coolness (fast life history?), which causes low IQ, and executive dysfunction, which causes even lower IQ.