Research from Yale University and the University of Colorado suggests that physical warmth and emotional warmth are linked. In fact, the temperature of the drink you're holding could influence your feelings of trust and tenderness toward toward the people around you.
In a study published in the journal Science, researchers asked a group of undergraduates to answer a series of hypothetical questions about a fictitious person's personality traits. But first, on an elevator ride to the lab, an overburdened-looking lab worker holding a steaming hot or icy cold coffee cup, two textbooks and a clipboard asked the participant to briefly hold the cup while she rifled through papers .
"It's casual, incidental," said John Bargh, professor of psychology at Yale University and a co-author of the study. "No one catches on that it has anything to do with [the study]."
But participants who held the hot coffee were more likely to later judge a fictitious person as having a warm personality. In a similar study in which participants were asked to hold a hot or cold therapeutic pad, those with the hot pad were more likely to opt to give a gift to a friend rather than choose a gift for themselves.
"We easily talk about people being a warm person, a cold person," Bargh said. "Why do we use these words? Why are they so pervasive? Warmth and coldness are really built on physical ideas of warmth and cold and they can trigger emotions [...] We're showing that very mundane, simple acts of touching something warm or cold produces these kinds of simple effects. It's like a gateway to other people."
The reason, he says, may lie in a little-known region of the brain called the insula, or the insular cortex. The insula, a prune-sized section of the brain tucked between the temporal lobe and the parietal cortex, processes both physical temperature and interpersonal warmth. Feelings of disgust and cigarette cravings are also believed to be linked to this brain region.
The findings reinforce the importance of physical contact in early life, Bargh said. Breast feeding not only nourishes infants, but also warms them, fostering feelings of connectedness and trust.
"We are wired to associate -- when we're really tiny -- warmth with trust," Bargh said.
Nalini Ambady, a psychology professor at Tufts who studies social and perceptual judgments, said the study is provocative, but needs to be followed up with more research.
"Nobody before has shown that something quite as subtle as the heat of the hand can influence these kinds of judgments," Ambady said, but added that it fits in well with other research showing that subtle clues can leave profound impressions.
"From subtle facial cues, people can pick up expectations from another person and can act on these expectations without knowing," she said. The more we know about these social clues, the more we can act on them.
So what does it say about people who live in the South of France versus Quebec? Are they warmer, more trusting? Or about starting a romantic relationship in January? Are the odds stacked against it?
"We don't know that yet," Bargh answered. "For one thing, all we've done is 'touch temperature.' We don't know about ambient room temperature. Are people in Georgia more trusting than people in New England? We don't know where ambient room temperatures registered. But it could well turn out that room temperature makes a difference."
Bargh plans to conduct similar research using brain imaging to study the activity of the insula when primed by cold and heat.
Meanwhile, he has pledged to hold cold Pepsi when buying major purchases, and to stop drinking hot coffee while shopping online to resist becoming overly influenced.
"For years, when someone has come into my office, I've offered them a cup of coffee," he said. "I do it routinely, and now I'm glad that I do it."