Ever since Eve shared her apple with Adam, eating together has been a significant event.

"In most cultures and most religions," says research psychologist Michael Lewis, "as far back as Biblical times, gathering to break bread is an important societal function." Whether the food is shared by lovers, colleagues or heads of state, it is "an intimate act."

In today's fast-paced, dual-income society, says Lewis, "family meals play an especially critical role.

"Dinner is often the only activity the family does regularly, all together. With our busy life styles, mealtime serves as a vehicle to help maintain the family, by providing an opportunity to stay intimate, keep in touch and massage our relationships with other family members."

Supper's "super-significance" to the family made it the logical arena to study "the family as a learning environment," says Lewis, director of Educational Testing Service's Institute for the Study of Exceptional Children.

Although ETS is best known as "that place in New Jersey that does the SAT and GRE tests," says Lewis, "we also do research on intellectual development and growth. We've been following a group of 150 children since birth (they're now age 6) to see how they learn.

"We're particularly interested in how families affect a child's intellectual, social and emotional growth. There's been a lot of research on how a child's interaction with the mother influences development, but we've virtually ignored the impact of the father and siblings."

To study family interactions in as natural a way as possible, ETS researchers videotaped 50 families -- from the group of 150 -- at mealtime. The families represented, Lewis says, "a heterogeneous group, from working poor to Princeton aristocracy," consisting of two parents and from one to four children.

"The experimenters set up a camera in the room the family normally ate in," says Lewis, "turned it on, then left. We know the camera's presence had some effect on their behavior. You can't alter that, except by the unethical means of studying them without their knowledge. But they really seemed to forget about it, and we feel we got a very true picture of what goes on.

"Except, occasionally, a parent would start to yell at a child, then seem to remember the camera, pause slightly and continue on--in a calmer voice--to explain to the child the reasons for the scolding."

The videotapes were made in 1978, when the "target children" in the ETS study were age 3. It's taken three years to analyze the tapes, says Lewis, because the researchers complied data on a broad range of often subtle interactions -- from who talked to whom and how much, to who cleared the table and what was served for dessert.

The result, "Some American Families at Dinner," to be a chapter in an upcoming ETS book, concludes that eating is one of the least significant things that happens at a family meal.

"Mealtime can be looked at in many complex ways," says Lewis. "It's a time when kids learn, by observing their parents, about relationships . . . how adult men and women treat each other. They learn rules of behavior--like 'Use your fork' -- and of morality--like 'Share the last piece of pie with your little sister.'

"They learn about sex roles. For example, regardless of class, the mother was most likely to bring the food to the table. Even if a child knows that Mommy is a lawyer, what they see is traditional behavior at home. So that's what they learn. We saw no difference in sexual stereotyping between the children of women who work and those who don't."

The things kids absorb at mealtime, Lewis contends, have a major impact on the kind of person they become. In other words, you are as you eat.

The families studied didn't always eat dinner together, but dined with all members present at least twice a week. "We don't know," he admits, "if they would usually be watching TV had we not been there."

A common theme was "dinner as a place everyone gathered after the separation of the day to renew contact and share what's going on. The father was the primary focus of the sharing. About 40 percent of the mothers were not employed . . . they often coached the children to tell the father what their day was like."

The researchers were particularly interested in "how birth order affects development," says Lewis, 45, the youngest of two children and father of a 14-year-old son and an 11-year-old daughter.

"We know birth order affects IQ scores and school achievement. First-born females are the biggest achievers, and there are more firstborns in Who's Who than people of any other birth order.

"Since siblings have the same genetic inheritence, we want to examine other factors that influence their growth . . . like how they are treated at home."

The study showed fathers interacting with their sons considerably more than with their daughters. Fathers also tended to pay particular attention to their firstborn -- regardless of that child's gender -- while mothers did not appear to make such distinctions.

"It's not a question of fathers loving a firstborn more," says Lewis, "just of paying more attention. Firstborns, especially males, sat next to the father. Perhaps it's tied in with the emotional impact of paternity . . . producing a first child as a demonstration of virility."

By contrast, middle children were spoken to much less frequently, and also did less speaking. "It was almost as if that middle child was not there," says Lewis. "We know that middle children are more likely to be in therapy than those of other birth orders."

While the youngest child was less likely to be talked to by the parents, they received attention from their siblings. Only children were spoken to by both parents--who talked more to the child than to each other.

"When the number of children increased," he notes, "so did the interaction between the parents. The adults could talk to each other more because the kids could keep each other entertained. Later-born children didn't get that intense focus of parental energy that first borns experience.

"Wives paid more attention to their husbands than husbands did to their wives. The typical scene was her talking to him and being sweet, while he's sitting there eating."

Food? "Upper-middle-class families eat more vegetables and pasta and less beef and pork . . . lower-class families tend to use dessert as a bribe more."

The biggest surprise, says Lewis, "was discovering the extent to which dinner is a time of regimentation. Parents seem to repeat an enormous number of rules endlessly--sit still, use your knife, chew slowly, don't reach, say please.

"I don't think we realize how much we use dinner to tell our kids what to do. It transforms the meal from a pleasant time of sharing to a tense time of criticism and social control."

Kids demonstrate that they know these rules, Lewis claims, by behaving properly when eating out. "But at home they relax, as adults do. Anyway, the real learning goes on by observing the adults.

"I'm not saying parents shouldn't instruct their kids, but it's a question of how much they do it."

For parents who aren't sure whether they're "going overboard," he suggests, "try allowing your mate to tell you what to do the same number of times you tell your kids what to do." "The things kids absorb at mealtime have a major impact on the kind of person they become."