The 1960s produced a dramatic change in the black American family's ability to pass on to its sons the social advantages it had manageed to acquire.

In the early '60s it didn't matter very much whether the family was poor or middle class - the son usually had to start on the botton rung of the job ladder.

By the early '70s, however, he was much more apt to start out in life at, or rise to, the status level of his father, and his career was more apt to reflect the advantages bestowed by his parents.

The substantial change was found in a study of social mobility in 1962 and in 1973 by two University of Wisconsin sociologists, Robert M. Hauser and David L. Featherman, who have published their findings in a number of journals.

"Something happened that enables black parents to transmit a substantial share of their social advantages to their son," Featherman said in an interview. "Whatever it is allows the black sons to utilize the resources of their families as stepping stones to their own occupational achievements." It occurs, he said, "to a far greater degree than in the early 1960s."

"It seems that there was a kind of lid on the black families in this respect and that now the lid is being taken off, in that the blacks are more able to pass on advantages just like whites alway have," Featherman said.

Their statistical study does not explain what it was that happened. They speculate that a decline in job discrimination may have played a part. Also, they found education played a stronger role in the black's mobility in 1973 than in 1962. The study did not include daughters.

Not much had changed for whites. There was no significant difference during the period in the correlation between the white family's status and its son's social mobility.

Both the 1962 and 1973 studies were based on special questionnaires added to routine surveys of employment conducted by the U.S. Census Bureau. The one in 1962, a pioneering effort, was conducted by Otis Dudley Duncan and Peter Blau. Featerstone and Hauser repeated the survey in 1973 to test the changes of a generation.

Both surveys matched the person's job with his family background, based on such characteristic as the father's job, number of children, years of education and income.

The 1962 study had shown as expected, that white families regularly transmitted their advantages to their sons. A stable upper-middle-class family with my years of education, few children and a high income conferred-on its son advantages which were highly likely to move him into the upper-middle-class of his generation.

The study that year found very little correlation of that sort for blacks.

"In 1962 there was little relationship between the occupational position of a black man and that of his father (or other family head)," the sociologists wrote in one recent article.

" . . . Black men born at the bottom of the occupational hierarchy stayed at the bottom, and even those few born into white-collar families were mainly destined to enter lower mantual occupations."

By 1973, the pattern had changed. Black sons of farmers and manual workers were much more apt to have reached white-collar jobs, and the sons of white-collar workers were more apt to hold white-colar jobs.

The 1962 study had found that elements of family background important to white offspring had little to do with blacks.

"Notably, neither a highly educated nor a high-status father was much of an advantage to a black man," they wrote, "and neither growing up in a large family nor in a broken family imposed as large a handicap as among the white men." By 1973, the black man was benefitting much more from the advantages of well-schooled, high-status parents.

For example, in the 1962 study, only one son out of 10 from an "upper white-collar" family was in a similar occupation. By 1973, one in every three from that status had, in effect, followed in his father's footsteps up the ladder to that level.

In 1962, 60 per cent of the sons from upper white-collar families were occupied in low-level manual occupations. In 1973, only 35 per cent and undergone such a status decline.

Most of these mobility changes had occurred among young blacks, those entering the labor force between 1962 and 1973. But there was evidence of higher mobility for some in their middle ages, Hauser and Featherman reported.

They also discovered a striking change in the degree to which education has helped blacks achieve higher occupations. Education, measured by years of schooling, has always been a powerful force propelling whites into the higher status occupations; it has been much less of a force for blacks.

The sociologists found the gap to be closing. In 1962, a year of school was worth almost 3 times as much in occupational status to a white man as to a black man. In 1973, it was worth only about 1 1/2 times as much.