Mental deficiency is a group of diseases in which the general intellectual function is significantly lower than the level of the same age during the development period, and is accompanied by adaptive behavioral defects.
The intelligence quotient (IQ) is 2.0 Standard deviations lower than the population mean (the population's mean IQ is set as 100, and the IQ value of one standard deviation is 15). Generally, an IQ below 70 (or 75) means that the intelligence is significantly lower than the average level.
Adaptive behavior includes two aspects: personal life ability and fulfillment of social responsibilities. The developmental period generally refers to those under 18 years of age.
Mental retardation goes by various names. Psychiatry calls it "mental retardation," "mental retardation," or "mental defect."
Education and psychology call it "intellectual retardation" and "intellectual deficiency".
In pediatrics, it is called "mental retardation", "mental retardation", and "mental development disorder".
Special education schools are called "retarded" and "intellectually disabled".
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