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.

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.