The 20th Century wall of ignorance, prejudice, and hostility that confronted my parents as they sought help for their retarded son actually displaced much positive and humane work in the field that had been started in the 19th century, according to authorities.

In 1801 French psychiatrist Jean-Marc Gaspard Itard published the results of his years of work with Victor, a retarded adolescent abandoned in the woods who became known as the "Wild Boy of Aveyron."

Itard had devised a successful senes of procedures designed to stimulate Victor, arouse his curiosity, and encourage him to care for himself - procedures that authorities say anticipate work that is done today.

Victor, as a result of Itard's work learned to walk upright, feed and clothe himself, and use language - social improvements that eletcrified the medical community at the time.

As a result of Itard's historic work, emphasis in this country and elsewhere was placed on training and educating the mentally handicapped, an empasis that was all but ended by what one authority called a "tragic" coincidence of three events.

The first was the introduction of the Binet Intelligence Test in 1908, which gave researches for the first time a seemingly objective method for measuring intelligence. It also gave them a dispassionate method of determining who should and should not be "allowed" to function in society.

Several years later, in 1912, a series of works that are now regarded as pseudoscientific bombast were published. They claimed that retardation was strictly genetic in nature, that it "ran in the family," and that anyone who was retarded should be locked up and sterilized so as not to "contaminate" society, according to Dr. Frank J. Menolascino, an activist in the fight for improved handling of the retarded.

Finally, at the same time, the European notions of psychoanalysis began to have an impact in America, putting more emphasis on analyzing the problem rather than helping the retarded learn how to cook, and shop and take care of themselves.

The result was that the large state institutions, which until then had given comparatively humane care to the retarded changed radically, often resembling penal institutions.Meanwhile, states passed mandatory sterilization laws and aimed at the retarded and cut back in their funding of facilities handling the retarded.

"Retardation is a dynamic condition. It can change with time," said Michael J. Begab, head of the Mental Retardation Research Centers branch of the Department of Health. Education, and Welfare, reflecting today's thinking in the field.

Circumstances such as education, social counseling, factors that can and have an impact on retardation, and lifelong guidance, are now receiving more attention than ever before, he said.

As a rule of thumb, 3 per cent of the U.S. population, or 6.3 million persons, is retarded, according to federal figures.

About 75 per cent of all retarded people was mildly retarded, with IQ's ranging between 50 and 70 (with 100 considered as average). This most prevelant form of retardation is most frequently caused by such social and nonorganic factors as poor inadequate nutrition during pregnancy and poor mental stimulation immediately after birth, he said. It can also be caused by inborn errors of metabolism and accidents at birth, Begab said.

The moderately retarded, those with IQ's from 30 to 50, make up about 15 per cent of the total, while the profoundly and severely retarded with IQ's from 0 to 30 make up about 10 per cent of the whole, Begab said. The retardation of people in these groups is almost exclusively caused by biological factors.

The moderately retarded can be taught to work in sheltered workshops and other supervised environments, while some of the profoundly and severely retarded can with great effort be trained to feed themselves and use toilet, he said.