With the catastrophe of global climate change looming, the implications of changing temperature patterns—on our habitats, health, food options, and even the economic and political landscape—are everywhere. But changes in temperature can affect humans’ psychology in more mundane ways, too. A spate of new research sheds light on the complex relationship between temperature, mood and behavior.
Cold makes us ascribe premeditated acts to criminals
According to a new paper in the journal PLOS ONE, people are more likely to believe criminals have committed premeditated—or “cold-blooded”—crimes when they themselves are cold. “We know there’s a close interplay between the experience of temperature and the perception of people,” said Christine Gockel, a professor at Switzerland’s University of Fribourg who coauthored the paper. Gockel and a team of Swiss and German psychologists recruited 147 students from Germany’s Chemnitz Technical University and assigned them to sit in one of three rooms, whose temperatures spanned the range of what’s comfortable: a chilly 67.8-degree-Fahrenheit one, a comfortable 74.8-degree room or a warm 79.2-degree room. Once the volunteers had adjusted to the temperature, the researchers showed them mug shots of eight criminals—four male and four female—and asked them to guess what kind of crime each person had committed. Students in the cold room were more likely to speculate that the accused had committed murder: They attributed an average of 0.77 murders to the eight criminals, whereas their peers in the medium-temperature and warm rooms attributed, respectively, 0.38 and 0.36 murders to the people in the photos. Cold students were also more likely to guess that the felons’ crimes were premeditated: On a scale of 1 (“least likely”) to 7 (“most likely”), students in the cold room ranked the likelihood that criminals had planned their crimes as 4.65, compared to 4.33 in the medium-temperature room and 4.01 in the warm room. Conversely, the hotter the students were, the more likely they were to say the criminals’ acts were impulsive—or “hot-headed.” On the 1-to-7 scale, warm students estimated the likelihood of impulsive crimes as 4.49; this number dropped to 4.27 in the medium-temperature room, and 4.04 in the cold room. Interestingly, though the study was conducted in German, the metaphors are the same in English; Russian and Chinese have similar metaphors, too. “Our abstract descriptions of people are grounded in concrete physical experiences,” said Gockel. “When we experience a warm temperature as children, that might mean we are being held tightly by a caretaker—that’s a very close and warm relationship, and that's how we learn these associations.”
Cold makes us perceive others as “cold”
Even a brief experience of warmth or cold can have a tangible effect on interpersonal judgment. In a 2008 paper in Science, John Bargh, a psychologist at Yale, and Lawrence Williams, who studies marketing at the University of Colorado at Boulder, explored the effect of briefly holding a hot or cold beverage on participants’ perceptions of another person’s character. Williams and Bargh recruited 41 students to take part in what they thought was a simple study on personality. Each volunteer was met by a confederate in the lobby of the psychology building and asked to hold their cup of coffee—either hot or iced—while riding the elevator to the lab on the fourth floor. When participants arrived at the lab, they were asked to read a description of “Person A” and rank his personality on a scale of “warm” to “cold.” As the researchers predicted, the people who had held the hot coffee ranked the target person as significantly “warmer”—4.71, on a scale of 1 (cold) to 7 (warm)—than those who held the iced coffee (4.25). Like Gockel, Williams and Bargh believe that metaphors are based on physical experiences: “The feelings of warmth when one holds a hot cup of coffee or takes a warm bath might activate memories of other feelings associated with warmth (trust and comfort), because of early experiences with caretakers who provide warmth, shelter, safety, and nourishment.”
Cold keeps us sharp
Research has suggested that cold weather might improve people’s focus and memory. For a 2009 paper in the Journal of Experimental Social Psychology, a team of psychologists led by Joseph Forgas, a professor at the University of New South Wales in Australia, placed ten unusual objects, such as toy cars and a piggy bank, on the counter of a small shop in Sydney, and asked 70 shoppers whether they remembered the objects as they left the store. They conducted half of the experiment on cold, rainy days, and half on bright, sunny days. Forgas found that the customers who went shopping on cold days could recall three times as many of the objects as the customers who went shopping in the sun. And employers have long suspected that chilly temperatures keep workers sharp: Back in the 1950s, a study of typists found that air-conditioning increased productivity by 25 percent.