That morning cup of coffee could give you a rosier outlook on the world. New research reveals that individuals who held the warm beverage viewed a stranger as having warmer personality traits than when holding an iced coffee.
In addition to viewing others as more trustworthy and caring, individuals who held a warm object also were more generous with others.
The results support the idea that physical warmth is linked with psychological warmth, and also suggest the link could be deeply rooted in our psyche perhaps from when we were infants being held by our warm mothers.
"I think that we have pretty deep and enduring associations between physical warmth and psychological warmth, interpersonal warmth, that are the result of perhaps many years of learning," said researcher Lawrence Williams of the University of Colorado at Boulder.
For instance, we might consider a warm person as someone who is helpful, friendly and trustworthy, researchers say.
To figure out this warm connection, the researchers had a study scientist ask each of 41 undergraduate students, 27 of whom were female, to hold either a cup of hot coffee or iced coffee while in an elevator en route to another floor in a building. While holding the coffee, participants gave their names and other basic information.
The subjects were then given a packet of information about an individual and asked to rate that individual's personality traits, including those related to the warm-cold personality factors, such as generous/ungenerous, happy/unhappy, good-natured/irritable, sociable/anti-social and caring/selfish.
Participants assessed the stranger as significantly "warmer" if they had previously held the warm coffee rather than the iced version. On personality features unrelated to warmth, the researchers found no difference in responses between the warm-cup and cold-cup holders.
The researchers also tested the link between physical warmth and warm behaviors. Participants who held heated or frozen therapeutic packs supposedly as part of a product evaluation study were told they could receive a gift certificate for a friend or a gift for themselves. Individuals who held the hot pack were more likely to ask for the gift certificate. The cold-pack carriers 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," said researcher John Bargh, a Yale University psychologist. "Physical warmth can make us see others as warmer people, but also cause us to be warmer — more generous and trusting — as well."
The association between physical heat and warm, fuzzy thoughts could be etched into the architecture of our minds, Williams said. In fact, past research has shown the insula region of the brain is involved in processing information from both physical temperature and interpersonal warmth, or trust.
"It's an association that's learned since early childhood when people are being held and cared for by their caretakers and experiencing love and affection," Williams told LiveScience. "At the same time they're experiencing physical contact with warm objects, and in that case another human being."
We wouldn't necessarily be aware of the link, though.
"It could be that just having this brief contact with a warm object brings to the forefront of the mind all of these associations with warm objects, including these feelings of love and affection," Williams said. "They may not penetrate through the barrier to come into consciousness."
The National Institutes of Health funded the study, which will be detailed in the Oct. 24 issue of the journal Science.
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Jeanna served as editor-in-chief of Live Science. Previously, she was an assistant editor at Scholastic's Science World magazine. Jeanna has an English degree from Salisbury University, a master's degree in biogeochemistry and environmental sciences from the University of Maryland, and a graduate science journalism degree from New York University. She has worked as a biologist in Florida, where she monitored wetlands and did field surveys for endangered species. She also received an ocean sciences journalism fellowship from Woods Hole Oceanographic Institution.