With hot coffee, we see a warm heart, researchers find

October 23, 2008

Our judgment of a person's character can be influenced by something as simple as the warmth of the drink we hold in our hand.

In the current issue of the journal Science, Yale University psychologists show that people judged others to be more generous and caring if they had just held a warm cup of coffee and less so if they had held an iced coffee. In a second study, they showed people are more likely to give something to others if they had just held something warm and more likely take something for themselves if they held something cold.

The study builds upon earlier work by the authors that shows the physical distance between individuals also influences their social judgments about another person.

The research suggests that saying that someone is warm or that you feel distant from a friend or relative are more than simple metaphors. They are literal descriptions of emotions such as trust, first experienced during the intimate bond formed between mother and child during infancy.

"When we ask whether someone is a warm person or cold person, they both have a temperature of 98.6 " said John A Bargh, a professor of psychology at Yale and co-author of the paper with Lawrence E. Williams of the University of Colorado who received his Ph.D. from Yale earlier this year. "These terms implicitly tap into the primitive experience of what it means to be warm and cold."

Psychologists have long noted the importance of warm physical contact with caregivers in developing healthy relationships as adults. So Bargh and Williams decided to test the impact of warmth on the perceptions of adults.

To test their hypothesis about the importance of temperature, research assistants casually asked that the undergraduate test subjects briefly hold either a warm cup of coffee or iced coffee as they wrote down information. The subjects were then given a packet of information about an individual and then asked to assess his or her personality traits. The participants assessed the person as significantly "warmer" if they had previously held the warm cup of coffee rather than the iced cup of coffee. On personality scales unrelated to the trait of "warmth," the researchers found no difference in how participants who held an iced, versus hot, coffee responded.

In the second study, participants held heated or frozen therapeutic packs as part of a product evaluation study and were then were told they could receive a gift certificate for a friend or a gift for themselves. Those who held the hot pack were more likely to ask for the gift certificate, while those who held the frozen pack tended to keep the gift.

"It appears that the effect of physical temperature is not just on how we see others, it affects our own behavior as well," Bargh said. "Physical warmth can make us see others as warmer people, but also cause us to be warmer – more generous and trusting – as well."

The demonstration of the power of temperature on character assessment has been supported by recent brain imaging studies, Bargh noted. For instance, the experience of hot or cold stimulus has been shown to trigger strong activity in the insular cortex. Researchers have also implicated the same area of the brain in borderline personality disorder, a debilitating illness characterized by an inability to cooperate and near complete inability to determine whom to trust.

Source: Yale University