Returning to the ban on psychotechnics and pedology in the USSR in 1936 (as well as IQ tests).
One of the achievements of psychotechnics and pedology in the 1920s and early 1930s was the establishment of schools for mentally disabled children in the USSR. Under the Tsarist regime, these schools were not included in the curriculum. But the same IQ tests and other tests revealed an unflattering truth: even among the children of Slavic nations, the proportion of imbeciles (with an IQ of 50-60) was up to 20%, and together with mild mental retardation (IQ 60-75), it was 50-60% of children. Among the children of backward nations, the proportion was even higher. In fact, most schools in the USSR were supposed to become "special schools."
The results of this are described in N. Kurek's book "The History of the Elimination of Pedology and Psychotechnics in the USSR," published in 2004.