"(The prevalence of classic Kanner autism, which is associated with moderate mental retardation, has not increased over the years.)"
"Asperger, unlike Kanner, included people who had average to high IQs in his definition"
In his 1943 article Autistic Disturbances of Affective Contact, Kanner said:
"With the non-language items of the Binet and Merril-Palmer tests, she [case 6, Virginia S.] achieved an IQ of 94. 'Without a doubt' commented the psychologist, 'her intelligence is superior to this'"
"A Binet test was attempted ... He [case 8, Alfred L.] finally complied in most instances in a manner that clearly indicated that he wanted to get through with the particular intrusion; this was repeated with each individual item in the test. In the end he achieved an IQ of 140." [Note: Alfred L and Virginia S were the only two children who cooperated enough for an IQ test.]
"Even though most of these children were at one point or another looked upon as feebleminded, they are all unquestioning endowed with good cognitive potentialities... The astounding vocabulary of the speaking children, the excellent memory for events of several years before, the phenomenal rote memory for poems and names, and the precise recollection of complex patterns and sequences, bespeak good intelligence in the sense in which this word is commonly used."
So clearly Kanner described children with average and above average IQs. Nowadays, the less cooperative children would likely have been tested and their refusals interpreted, robot-like, as wrong answers, just like my autistic friend who was declared profoundly delayed because he didn't cooperate at all with the test. Personally, I think Kanner's way, of declaring them 'untestable' and observing spontaneous signs of their abilities, is more fair.
"Kanners usually have a below-normal IQ
while Aspergers have a normal-above IQ
Kanners usually have a delay in speech
Aspergers usually don't"
The first part of these two statements is the same as the previous two innacurate statements. As for the second part, here's another quote from his 1943 article:
"Eight of the eleven children acquired the ability to speak either at the usual age or after some delay." [Of the speaking children, at least 5 spoke their first words before age 2, and at least 3 were using sentences by age 3.]
Although communication impairment, such as echolalia and not using speech communicatively, was present in all of Kanner's cases, most learned to speak, many at the usual age.
"Kanner’s Syndrome is often the lowest functioning end of the disorder, and these children (and adults) tend to be very drawn into themselves and have extremely limited communication skills."
"Kanner described children who were severely affected. His description, and the downbeat prognosis persisted for the next 30 years."
Regarding low functioning, Kanner's highest functioning case was Donald T., who in his follow-up in 1971 was described as such:
"Since receiving his AB degree in 1958, he has worked as a bank teller. He is satisfied to remain a teller, having no real desire for promotion. He meets the public there real well. ... He takes very little part in social conversation and shows no interest in the opposite sex. While Don is not completely normal, he has taken his place in society very well, so much better than we ever hoped for. If he can maintain status quo, I think he has adjusted sufficiently to take care of himself." [He wrote another article in 1972 giving case descriptions of several high functioning autistics.]
The prognosis was originally described in 1943 as:
"Five of our children have by now reached ages between 9 and 11 years. Except for Vivian S., [sic] who has been dumped in a school for the feebleminded, they show a very interesting course. The basic desire for aloneness and sameness has remained essentially unchanged, but there has been a varying degree of emergence from solitude ... Between the ages of 5 and 6 years, they abandon the echolalia and learn spontaneously to use personal pronouns with adequate reference. Language becomes more communicative, at first in the sense of a question-and-answer exercise, and then in the sense of greater spontaneity of sentence formation. ... Between the ages of 6 and 8, the children begin to play in a group, still never with the other members of the play group, but at least on the periphery alongside the group. Reading skill is acquired quickly"
Kanner made his opposition to institutionalizing autistics clear, and predicted poor outcomes for them, but if cared for in their own or a foster home, he predicted they would improve. A few would become high functioning enough to live and work independently, and those who didn't could still contribute.
"Kanner regarded autism as a consequence of harmful childrearing practices."
And here they confuse him with Bruno Bettelheim, it seems. From his 1943 article:
"In the whole group, there are very few really warmhearted mothers and fathers. ... Even some of the happiest marriages are rather cold and formal affairs. Three of the marriages were dismal failures. The question arises whether or to what extent this fact has contributed to the condition of the children. The children's aloneness from the beginning of life makes it difficult to attribute the whole picture exclusively to the type of the early parental relations with our patients. We must, then, assume that these children have come into the world with innate inability to form the usual, biologically provided contact with people, just as other children come into the world with innate physical or intellectual handicaps. If this assumption is correct, a further study of our children may help to furnish concrete criteria regarding the still diffuse notions about the constitutional components of emotional reactivity. For here we seem to have pure-culture examples of inborn autistic disturbances of affective contact."
And in his follow-up:
"As for the all-important matter of etiology, the early development of the 11 children left no other choice than the assumption that they had 'come into the world with an innate disability to form the usual, biologically provided contact with people.' ... One can say now unhesitatingly that this assumption has become a certainty. Some people seem to have completely overlooked this statement, however, as well as the passages leading up to it and have referred to the author erroniously as an advocate of postnatal 'psychogenicity.'"
So even in the 1970s, it was already going on. People mischaracterized Kanner's words even back then. But back then, he could counter them.
Lastly, I couldn't find a specific quote, but I've read of children who developed normally until 18 months or so and then regressed being referred to as having 'Kanner autism'. Only one of Kanner's cases showed any regression, Richard M. (regression in pre-speech skills) but before his regression, he was described this way:
"The mother, in comparing her two children, recalled that while her younger child showed an active reaction to being picked up, Richard had not shown any physiognomic or postural sign of preparedness and had failed to adjust his body to being held by her or the nurse."
Kanner emphasized that these children were all noticeably abnormal in early infancy, commenting that they could not be called 'withdrawn' because they'd never been connected in the first place.