They asked people to briefly hold a hot or iced coffee. Then they were given a packet of information about another person and asked to assess his or her personality traits.
Those who had held the warm cup of coffee were far more likely to assign "warmth" as a personality trait than those who held the icy beverage.
Those who had held the hot pad were more likely to ask for the gift certificate, while those who held the frozen pack tended to keep the gift.
Williams said it is no accident that people in Western cultures looking to build new relationships often do it over coffee. "It's better than going out for ice cream," he said.