By BENEDICT CAREY

Artful persuasion depends on eye contact, but not just any kind. If one person prefers brief glances and the other is busy staring deeply, then it may not matter how good the jokes are or how much they both loved “Juno.” Rhythm counts.

What behaviors do you notice you have picked up from other people?

Voice cadence does, too. People who speak in loud, animated bursts tend to feed off others who do the same, just as those who are lower key tend to relax in a cool stream of measured tones.

“Myself, I’m very conscious of people’s body position,” said Ray Allieri of Wellesley, Mass., a former telecommunications executive with 20 years in marketing and sales. “If they’re leaning back in their chair, I do that, and if they’re forward on their elbows, I tend to move forward,”

Psychologists have been studying the art of persuasion for nearly a century, analyzing activities like political propaganda, television campaigns and door-to-door sales. Many factors influence people’s susceptibility to an appeal, studies suggest, including their perception of how exclusive an opportunity is and whether their neighbors are buying it.

Most people are also strongly sensitive to rapport, to charm, to the social music in the person making the pitch. In recent years, researchers have begun to decode the unspoken, subtle elements that come into play when people click.

They have found that immediate social bonding between strangers is highly dependent on mimicry, a synchronized and usually unconscious give and take of words and gestures that creates a current of good will between two people.

By understanding exactly how this process works, researchers say, people can better catch themselves when falling for an artful pitch, and even sharpen their own social skills in ways they may not have tried before.

“Really good salespeople, and for that matter good con artists, have known about these skills and used them forever,” Jeremy Bailenson, a psychologist at Stanford, said. “All we’re doing now is measuring and describing more precisely what it is they’re doing, whether consciously or not.”

Imitation is one of the most common and recognizable behaviors in the animal kingdom. Just as baby chimps learn to climb by aping their elders, so infants pick up words and gestures by copying parents. They sense and mimic peers’ behavior from early on, too, looking up at the ceiling if others around them do so or mirroring others’ cringes of fear and anxiety.

Such behavioral contagion probably evolved early for survival, some scientists argue. It is what scatters a flock well before most members see a lunging predator.

Yet by drawing on apparently similar skills, even in seemingly trivial ways, people can prompt almost instantaneous cooperation from complete strangers.

In a recent experiment, Rick van Baaren, a psychologist at Nijmegen University in the Netherlands, had student participants go to a lab and give their opinions about a series of advertisements. A member of his research team mimicked half the participants while they spoke, roughly mirroring the posture and the position of their arms and legs, taking care not to be too obvious.

Minutes later, the experimenter dropped six pens on the floor, making it look like an accident.

In several versions of this simple sequence, participants who had been mimicked were two to three times as likely to pick up the pens as those who had not.

The mimicry had not only increased good will toward the researcher within minutes, the study concluded, but it also prompted “an increased pro-social orientation in general.”

That orientation applies to far more than dropped pens. In a study due out in the spring, Robin Tanner and Tanya Chartrand, psychologists at Duke, led a research team that tested how being mimicked might affect the behavior of a potential client or investor.

The team had 37 Duke students try out what was described as a new sports drink, Vigor, and answer a few questions about it. The interviewer mimicked about half the participants using a technique Dr. Chartrand had developed in earlier studies.

The technique involved mirroring a person’s posture and movements, with a one- to two-second delay. If he crosses his legs, then wait two seconds and do the same, with opposite legs. If she touches her face, wait a beat or two and do that. If he drums his fingers or taps a toe, wait again and do something similar.

The idea is to be a mirror but a slow, imperfect one. Follow too closely, and most people catch it — and the game is over.

In the study, the researchers set up the interviews so each student’s experience was virtually identical, except for the mimicking.

None of the copied participants picked up on the mimicry. But by the end of the short interview, they were significantly more likely than the others to consume the new drink, to say they would buy it and to predict its success in the market.

In a similar experiment, the psychologists found that this was especially true if the participants knew that the interviewer, the mimic, had a stake in the product’s success.

“This is somewhat counterintuitive,” Dr. Chartrand said in an interview. “Normally, you’d expect when people realize that someone was invested in a product and trying to sell it to them, their reaction would be attenuated. They’d be less enthusiastic.

“But we found that people who were mimicked actually felt more strongly about the product when they knew the other person was invested in it.”

Any amiable conversation provides ample evidence of this subconscious social waltz. Smiles are contagious. So is nodding, in an amiable conversation.

Accents converge quickly and automatically. A country chime or an Irish whistle can seemingly infect the voice of a New Yorker in a 10-minute phone call.

“I especially find myself falling into a Southern accent, which is crazy,” Mr. Allieri, the telecom executive, said. “I’m from Boston.

“But I think what good salespeople really do is pick up on physical cues and respond to them without thinking much about it.”

It is one thing to move like a naturally synchronized swimmer through the pools of everyday conversation without thinking, however. It is another to deliberately employ mimicry to persuade or seduce.

Dr. Bailenson, the Stanford psychologist, has been testing the effects of different forms of mimicry by programming a computer-generated figure, an avatar, to mirror the movements and gestures of people in a study.

He has found that his subjects pick up the mimicry when it is immediate and precise. If the avatar is slightly out of sync, however — waits four seconds, for instance — then the mimicking goes unnoticed, and the usual rules apply. The virtual creating comes across as warm and convincing, as if controlled by another human.

“The point is it’s a delicate balance to get it right, and I suspect that people who are good at this know how to do it intuitively,” Dr. Bailenson said.

Or they have developed ways to engage their skills indirectly.

Veldon Smith, a musician and legendary salesman living in Centennial, Colo., who spent 30 years in the automobile parts business before retiring a few years ago, said:

“One thing I always did, I learned as much as possible about a client before I visited, what their problem was, what they were worried about. Then I would go in with a story about myself being in the same predicament.

“So when I walked in, I was in exactly the same frame of mind as the customer. I was immediately on the same wavelength. Everything else kind of flowed out of that.”

One reason subtle mimicry is so instantly beguiling may be that it draws on and, perhaps, activates brain circuits involved in feelings of empathy.

In several studies, Jean Decety, a neuroscientist at the University of Chicago, has shown that some of the same brain regions that are active when a person feels pain also flare up when that person imagines someone else like a loved one feeling the same sting or ache.

A similar process almost certainly occurs when a person takes pleasure in the good fortune of a friend or the apparent enjoyment of a conversation partner, Dr. Decety said.

“When you’re being mimicked in a good way, it communicates a kind of pleasure, a social high you’re getting from the other person, and I suspect it activates the areas of the brain involved in sensing reward,” he said.

Social mimicry can and does go wrong. At its malicious extreme, it curdles into mockery, which is why people often recoil when they catch of whiff of mimicry, ending any chance of a social bond. Preliminary studies suggest that the rules change if there is a wide cultural gap between two people. For almost everyone else, however, subtle mimicry comes across as a form of flattery, the physical dance of charm itself. And if that kind of flattery doesn’t close a deal, it may just be that the customer isn’t buying.