ON a brisk autumn afternoon, in the shadow of the marble arch in Washington Square Park, a couple visiting from Ohio walked along holding hands like two teenagers going steady, decades after “going steady” went out of vogue.

When a stranger asked why they had chosen to join hands during their stroll, the man, Dave Findlay, looked at his wife of seven years and answered in a word: “Connection.”

Or as the Beatles sang back in 1963: “When I’ll feel that something, I want to hold your hand.”

Those simple lyrics turned an expression of teenage longing and first romantic steps into a No. 1 hit. Yet today, when Justin Timberlake is at the top of the charts with “SexyBack” and the digital airwaves are filled with steamy lyrical declarations (“I’m into havin’ sex, I ain’t into makin’ love” sang 50 Cent in “In da Club”), couples like Dave and Carey Findlay still intertwine fingers, kiss palms and link pinkies as they meander through parks, cross streets and snake through crowds.

“Hand-holding is the one aspect that’s not been affected by the sexual revolution,” said Dalton Conley, a professor and chairman of the department of sociology at New York University. “It’s less about sex than about a public demonstration about coupledom.”

Nowadays hand-holding has attracted the interest of scientists who are studying its effects on the body and mind. And sexual health educators say it is a much-discussed topic among gay students who now publicly hold hands more than ever before but still must consider whether they want to declare their sexuality.

“I think it remains more important in an era of perhaps more liberal sexual norms,” Dr. Conley said. “It remains this thing to be doled out.”

To hold someone’s hand is to offer them affection, protection or comfort. It is a way to communicate that you are off the market. Practically speaking, it is an efficient way to squeeze through a crowd without losing your partner. People do it during vigils, marches, weddings and funerals.

Usually it connotes something innocuous and sweet about a couple and their relationship. In rare instances, it takes on added potency, such as when President George W. Bush held the hand of Crown Prince Abdullah of Saudi Arabia in Crawford, Tex., last year — an act of respect and affection in Arab countries — reminding some people of the film “Fahrenheit 9/11,” which depicted the Bush family’s close business ties to Saudi leaders and which ignited conspiracy theories.

But, over all, few things are more innocent than a child grabbing the hand of a parent, for protection, direction and, as Mr. Findlay put it, connection. And with many children these days closer and more outwardly affectionate to their parents, chances are you have spotted a mother and her teenage daughter and perhaps even a father and his adolescent son ambling through a mall, scurrying through a crosswalk or strolling along, hand in hand.

Adult children and their elderly parents also hold hands, for balance, support and as a sign of love.

As for romantic couples, the opinions about hand-holding are as varied as fingerprints. But most people agree that it has merely changed, not lost favor.

“I think that for sure college students hold hands just like the old days,” said Sandra L. Caron, a professor of family relations and human sexuality at the University of Maine in Orono.

If they do, it is likely only after they are deep into a relationship — not in those early days of budding romance, when a touch of hands was the first act of intimacy between a couple. That was the hand-holding that the Beatles wrote about. (Followed swiftly by the sexual revolution, whose equivalent anthem might be The Rolling Stones’ “Let’s Spend the Night Together.”)

Among more than a half-dozen students at the University of Maine, there seemed to be two universal truths: that hand-holding is the least nauseating public display of affection and that holding hands has become more significant than other seemingly deeper expressions of love and romance.

“It is a lot more intimate to hold hands nowadays than to kiss,” said Joel Kershner, 23. Because of that, he said, reaching for someone’s hand these days has more potential for rejection than leaning in for a smooch at a party where alcohol is flowing.

Libby Tyler, 20, said it was “weird that hand-holding is more serious,” but true. “It’s something that you lead up to,” she said.

There is nothing casual about it any more, said Rachel Peters, 22. “Hand-holding is something that usually people do once they’ve confirmed they’re a couple,” she said.

But if that is not complicated enough, where you choose to hold hands also has meaning, the students said.

Drew Fitzherbert, 21, said that public hand-holding “shows that commitment not only to you and your partner but everyone else in the community.”

Dr. Conley of N.Y.U. agreed. “In the dark movie theater, in the dorm room, that’s a very different social act,” he said.

Are people holding hands as much as they once did? That’s impossible to quantify. But Gregory T. Eells, the director of counseling and psychological services at Cornell University in Ithaca, said he didn’t think so.

“I see more people on their cellphone than holding hands,” he said, adding, “To some extent we are trading real face-to-face relationships, where there’s touch and body language, for electronic ones.”

Peter Shawn Bearman, a professor of sociology and the director of the Institute for Social and Economic Research and Policy at Columbia University, said that hand-holding in crowded cities like New York may simply be impractical.

“Maybe if the proportion of hand-holders has indeed gone down it has more to do with density (of humans) than the devaluing of hand-holding as a romantic signal,” he wrote in an e-mail message.

Whatever degree of hand-holding may be happening, there are good reasons to cultivate the habit — reasons would-be hand-graspers may wish to pass along to their hands-in-pockets partners.

“Based on what we’ve seen, when we get more physical intimacy we get better relationships, whether a mother and an infant or a couple,” said Tiffany Field, the director of the Touch Research Institute at the University of Miami School of Medicine.

Even monkeys understand the importance of a hand squeeze every now and then. In “Good Natured: The Origins of Right and Wrong in Humans and Other Animals,” Dr. Frans B. M. de Waal, a primatologist at Emory University, wrote that some monkeys hold hands in reconciliation after a fight.

James Coan, an assistant professor of psychology and the neuroscience graduate program at the University of Virginia, has studied the impact of human touch, particularly how it affects the neural response to threatening situations, and said the results of a recent study were more dramatic than he expected.

“We found that holding the hand of really anyone, it made your brain work a little less hard in coping,” Dr. Coan said, adding that any sort of hand-holding relaxes the body.

The study, which will be published this year in the journal Psychological Science, involved 16 couples who were rated happily married based on the answers in a detailed questionnaire. The wives were put inside an M.R.I. machine and were told they were to receive mild electric shocks to an ankle. Brain images showed that regions of the women’s brains that had been activated in anticipation of pain and that were associated with negative emotions decreased when their husbands reached into the machine.

“With spouse hand-holding you also stop looking for other signs of danger and you start feeling more secure,” said Dr. Coan, who led the study. “If you’re in a really strong relationship, you may be protected against pain and stress hormones that may have a damaging effect on your immune system.”

Perhaps it is why so many people crave it.

Blogs and online forums are rife with complaints of those who say their significant other does not want to hold hands. “When we go out, we always have a blast, but the one thing that bothers me is that he never holds my hand in public,” writes a woman on a “love advice” forum on www.lovingyou.com.

For older couples, letting go of hand-holding may be one more sign that they are pressed for time and too swamped for little acts of intimacy.

“When do we make time to hold hands?,” said Dr. Eells of Cornell, talking about his own marriage of 15 years. “Not very often.”

The couple is often busy shuttling children to and from school and extracurricular activities, not strolling through parks like characters in a Georges Seurat painting.

Sometimes, though, even errands provide opportunities. Recently, Dr. Eells said, he and his 9-year-old daughter were caught in a downpour after her cheerleading practice. The two grabbed hands and raced off into the rain together. When they finally splashed over to the car, the damp girl turned her face to her father. “That was awesome,” she sighed.