In every age, psychologists say, toys reflect the concerns and values of their society. A century ago, marbles and fishing poles were common playthings. In today's technological society, robot dolls and computers are popular toys. This year, Americans will spend more than $540 million on Cabbage Patch dolls. What, then, does this say about society?

"I take them as message that loneliness has increased," said Brian Sutton-Smith, an educational psychologist from the University of Pennsylvania. "Once upon a time, soft toys were for babies. Now they're taken for granted as a feature of adult life."

It's no surprise, then, to learn that Coleco -- which manufactures the Cabbage Patch Kids -- says one in five of the homely, huggable dolls are owned by people over 18 years old. From college dorms to nursing homes, the dolls are silent companions to cuddle.

Cabbage Patch dolls are the most visible example of one of the fastest growing segments of the toy industry -- soft-bodied toys. The comforting nature of these squeezable playthings is particularly appealing in a stressful, impersonal world, said Sutton-Smith. Modern families often include only a child or two, hardly the boisterous packs of kids common a generation ago. The Cabbage Patch phenomenon implies "the notion of joy in adopting a child into a family which is smaller," he said.

The relationship of people to playthings is highlighted at Christmas when most American families gather to exchange and open gifts. In many of these households, toys are the most popular gifts.

But a troubling paradox pervades this ritual of toy giving, Sutton-Smith said. Gift-giving reinforces the social bond between children and parents, drawing them together against the society that threatens to pull them apart. The gifts remind the family of its togetherness. Yet most toys adults give to children are meant to be played with alone.

"What I see going on is this incredible gift binge at Christmas," he said. "And yet the apparent meaning of these things is the opposite of what the binging was for. The binging was for union, and the meaning was for individualism."

Loneliness, he said, may be one price we pay for individualism, a valued characteristic in American society. But the gifts that isolate also help prepare the child for adult life.

"An essential function of modern child-rearing is to turn the child into a person capable of functioning in isolation," he writes in his book "Toys as Culture," which will be published early next year. Successful adults often must work in isolation at impersonal activities, he said. The skills that allow them to achieve at these tasks are learned in childhood, through play that forms a base of information and skill.

Most of the history of play did not include toys for children. While children did sometimes use objects in their play, historians note, they often were objects intended for adult use and sacred rituals. Until the past few centuries, children were typically engaged in useful tasks related to hunting and taking care of babies. And these tasks often were done collectively by groups of children in ways that encouraged conformity.

But social conformity, Sutton-Smith noted, may not be the best way to raise a child. A main determinant of child genius in our own era is a solitary childhood. "Einstein," he said, "didn't grow up in a crowd."

People give children toys with a variety of motives, said Diana Kelly-Byrne, also an educational psychologist at the University of Pennsylvania. In part, she said, toys are favored gifts simply because it has become customary to give them. Sixty percent of the toys sold each year are purchased as Christmas gifts, according to the Toy Manufacturers of America.

Other motives include the pervasive emphasis on "hot-housing" -- intensive parental protection and attention to a child's development -- that begins from birth, Kelly-Byrne said. The toys are given not only for the child's pleasure, but because they enhance literacy or other skills -- the parent's ambitions for the child.

Finally, she says, parents buy toys because sometimes "we have to get the children off our backs. It's extremely exhausting for an adult to play with children all the time."

The need for parents to isolate their children, she said, comes from the "tremendous intensity" required in playing with them. An adult who is determined not to control a game is likely to find that a child typically changes the rules constantly, often with little notice or explanation.

"We have a tremendous investment in idealizing childhood and children rather than seeingwhat it is that children really do," she said. "They become cute because we want to see them as innocent and unself-conscious." Children actually learn to be "cute" and play in ways that match the vision adults have of their play world.

One definition of play, says Joan McLane, a child developmentalist at Chicago's Erikson Institute, is that it's a satisfying activity. "It's what the child wants to do," she said. "It's a risk-free situation that gives children the freedom to try out new ways of doing things. It gives them control in their own terms."

The best toys are those that stimulate the child's imagination, she said, which leads to abstract thinking. Others enhance manipulative skills or problem solving. For a young child, she suggests, blocks are a "wonderful" toy.

Adult play is often couched in terms of social activity or as a way to release the tensions built up through work. One reason why adults are drawn to the Cabbage Patch dolls is that the dolls look "sad, needy, and unattractive, like they need someone to take care of them," said Thomas Plant, a psychologist at the National Institutes of Mental Health. "We all feel like that some-times,"but society forces us to conceal those feelings of sadness or vulnerability. Even technological toys, he says, represent an "opportunity to escape from the demands of a job or a personal relationship that's all screwed up."

For whatever reason, today's adult toy market is vigorous. Exercise machines sold briskly this holiday season, merchants reported, and new portable head-set radios will accompany millions of adults to and from the job. At the novelty shop, Sharper Image, the Omnibot, a small robot that serves drinks, has been selling well, as has a "false beeper," which enables executives to free themselves from boring meetings.Children or adults who play alone may be more apt to develop creativity and imagination. "One thinks of toys and play as an area of great novelty and potentiality where all sorts of responses can be developed," said Sutton-Smith. "The fact that adults are allowing their imaginations to have activity through toy kinds of objects is a further reflection of the belief in the imagination of the adult mind."

In centuries past, children at play often tended to imitate adults, said American University historian Bernard Mergen in his book, "Play and Playthings." In modern times, though, the play of adults and children seems to have become more similar. "Instead of the child as a miniature adult," he wrote, "the modern adult may be an overgrown child."

Mergen called toys "the material artifacts of play," because they survive for generations, providing a record of the variety of objects that children have made and used.

Before toys were mass produced, he said, the word "plaything" referred to any object that could be transformed, through imagination, to do what the child willed. Thus, corncobs became dolls, sticks became horses, and with the advent of firearms, nearly anything that could be picked up and pointed became a gun.

"The Industrial Revolution added a vast toy store of play objects," he wrote, including washers, tires, paperclips, and bottle tops.

The toy industry arose in tandem with industrialization and the growth of the middle class. Children had more leisure time; adults had more money. As more adults came to work outside the home and farm, the focus of attention turned from the family to the workplace. By the 1800s, Sutton-Smith notes, "toys were used as a child's possessions, and more than anything else in a material culture, they made it clear that the child was distinct."

Popular toys were inspired by history, and reflected the tides of religion. In 1844, the W. & S.B. Ives Company introduced "The Game of Pope and Pagen, or the Seige of the Stronghold of Satan by the Christian Army." Four war games, titled "Union Games," marked interest in the Civil War, while toy guns echoed World War I combat in Europe.

In the 1880s, board games like "The Monopolist" followed the popular preoccupation with banking and commerce, and preceded the current version of "Monopoly" by more than 55 years. Disney-inspired toys dominated the 1930s, and interest in space toys accompanied the launch of Sputnik in 1957.

Toys popular with one generation may be updated to appeal to the next generation of children. For example, this year the Barbie doll shed her "Pink and Pretty" image and instead acquired a tailored suit and briefcase.

Interest in toys -- and the money spent on them -- is growing. The Toy Manufacturers of America reports that consumers spent an estimated $12 billion on toys last year, up from $10 billion in 1983. In the United States, 50,000 people work in the toy industry that produces 150,000 individual toy products, including up to 4,000 new ones every year.

As the industry grows, producers are spending considerably more time and money on research. Fisher-Price, which specializes in toys for infants and young children, operates a nursery school on the company premises in East Aurora, N.Y. For 6-week intervals, groups of children from infancy to age eight are invited to play with existing toys and those under development. Two state-certified teachers, as well as designers and engineers, observe their play. Older children, said Priscilla Hamlin, one of the teachers, are interviewed about which toys they like and dislike, and how they think the toys could be improved.

Danny Simpson, who works for The Child Growth & Development Corp. in Baltimore, tests babies' responses to toys for companies such as Johnson & Johnson. He says that in general, a good toy is one that engages the child's attention for the longest time.

As a child plays, Simpson records the child's responses -- such as looking, shaking, or listening -- to certain of the toy's features, such as content or housing. He also records how long the toy holds the child's interest. Ten minutes for an infant toy is considered good.

Very little in toy design is ever truly new. Bright colors and plastic materials may make the toys seem modern, but most toys build on classic features, and appear new because some novel feature has been added. For example, the most notable feature about a "yo-yo rattle" is that the familiar shakable device includes an object that moves up and down an interior track, Simpson said. Often, he finds, the child may notice the new feature -- in this case, the moving object -- but it is the toy's basic features, such as sound or shape, that draw and hold the child's attention.

Psychologists say that the best toys stimulate the child to explore or to develop motor or verbal skills. From the producers' perspective, though, the most successful toys both stimulate the child and attract the adult, who must purchase them. For instance, many adults give infants stuffed bears and dolls, but a year or more will pass before the toys claim the child's interest.

It is important to buy toys labeled for the child's age, said Penny Richman of the Toy Manufacturers of America. This helps to ensure both that the toy will be safe, and that the child will not be frustrated by a toy or game that is too advanced. A child who has rejected a toy may continue to reject it even when he or she is able to play with it, she said.

The educational value of toys has long been of interest to parents and a goal of manufacturers. In 1907, the industry magazine, "Playthings," wrote that a mother is likely to prefer toys for her children that are safe, difficult to break, and "instructive."

From this appeal to common sense values, AU's Mergen wrote, the editors and toy manufacturers "quickly developed a sophisticated awareness of current theories in education and child psychology."

By 1920, they were seeking the advice of educators, who encouraged toys that appealed to the child's imagination and artistic sense. By 1940, the toy producers preached that child's play was not just a pastime, but a means of growth, "both in mind and body," Mergen wrote.

While studies about play abound, scientific research on toys and their effect on the person playing with them are relatively few. And despite a parent's investment in toys, it is not clear that they are essential to a child's development, though play and objects to explore and manipulate seem to be, Simpson said.

Play and educational toys are now viewed as important to a child's growth, said Sutton-Smith, so "a toy is seen both as a bauble and as an intellectual machine." The child, he said, is both expected to play with the toy in a nonserious way, and to learn something serious from it.

"Play is not the child's work, as is often said," according to Sutton-Smith. "The child is too busy being intelligent (exploring, mastering, imagining and performing) to play most of the time. Work, not play, is the work of childhood."

It's not an empty gesture that parents bond themselves to kids by giving them toys, Sutton-Smith said. "This is a material society and they use material means to indicate emotional realities. I see this whole thing positively. We are what we are. The main point for me is that toys are incredibly more important than we realized. We should have known it."