CHARLOTTESVILLE, NOV. 6 -- A child care researcher suggested today that parents who rely significantly on day care for their infants may be playing Russian roulette with their children's personalities and social development.

Jay Belsky, a professor of human development at Pennsylvania State University, said at a conference of researchers here that his findings on the negative psychological effects of early child care may speak to a lack of good care available outside the home or to stresses in the families requiring child care.

Belsky created a firestorm among researchers last year when his studies led him to conclude that infants less than a year old who receive more than 20 hours a week of nonmaternal care are more likely to have insecure relationships with their parents. He also pointed to other studies showing such insecure children to be less competent and cooperative and to have more behavior problems in later years than other children.

"There is no reason to assume there is anything inherently risky about nonparental care in the first year of life," he told reporters after his presentation this morning on the University of Virginia campus. The problems he found are with care "as it is experienced and encountered" in this country.

"Are we playing Russian roulette with a generation? . . . There is evidence that we are," Belsky concluded.

Other researchers disputed his basic conclusions about the impact of infant care. Sandra Scarr, professor of psychology at the University of Virginia, said the critical time for developing relationships is not in the first several months of life.

"If parents had to choose a time to take off a few months to be with their babies, for the baby's benefit, it would not be the first few but the end of the first year and any time in the second year," Scarr told the conference. Earlier than that, she said, "their brains are Jell-O and their memories akin to those of decorticate rodents."

Only the most pervasive and disastrous experiences during early infancy would have any long-term negative effect on development, she said.

"Infancy is so protected by biological design . . . it is hard to throw them {infants} off for very long," Scarr told the group.

Scarr also said that a study she helped conduct with Bermudan children indicated that the effects of early day care on a child's development changed as the child got older, generally turning more positive as time went on. In addition, in abusive families, high-quality child care has been shown to compensate for a poor home environment, she said.

The debate on maternal care of infants is driven in part by qualms society continues to have about women in the work force, even at a time when nearly 60 percent of the mothers of infants work, Scarr charged. "Mothers and children are hostages to our national ambivalence about women in the labor force," she said.

Michael E. Lamb, a senior research scientist at the National Institute of Child Health and Human Development, told the conference that a study he conducted on 140 Swedish preschoolers who started care in their second year showed no difference in social skills and personality based on whether they were cared for at home, in a center or by a day care provider in another home.

Sweden was chosen because researchers could reduce the number of variables in parental values and in type of day care facilities.

One issue on which the researchers appeared to agree was the need for more high quality child care in this country.

"Child care policies are something for our nation to be ashamed of," Belsky said. His "disquieting" findings on infant care in the first year, he said, "may speak to that shame."