temperature influences our feelings -- 2/24/17

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Today's selection -- from "The Warmth of Friendship, the Chill of Betrayal" by Marta Zaraska. Temperature influences our feelings. A chill in the air can raise our suspicions, and a short dose of heat can bring feelings of trust:

" During the past decade scientists have discovered that our physical temperature can affect how 'warm' or 'cold' we feel toward other people. For instance, studies have found that when we are hurt, isolated or betrayed, a short dose of heat -- in the form of a hot beverage, warm bath or even the sun -- may help restore feelings of trust and bonhomie. Likewise, other investigations have shown that a chill in the air can raise our suspicions. In general, this line of inquiry belongs to a larger research field called embodied cognition, which holds that our body -- and not just our brain -- plays a role in our thinking, emotions and memories. The field has its critics, but when it comes to temperature, there is little doubt that the link between physical and psychological warmth and coolness is built on more than just metaphor. Researchers have uncovered overlapping mechanisms that govern both the system that regulates body temperature and the one that governs our emotional state. Imaging studies have tracked both systems to the insula in the cerebral cortex. And as neuroscientists and psychologists begin to understand this circuitry better, they are looking for ways to manipulate it to treat depression and other disorders that can put a freeze on our social connections. Yale University psychologist John A. Bargh first began exploring the links between physical and psychological temperatures in 2008. At the time, he says, his laboratory was 'scouting into a new territory about the warm-cold effect.' As part of that initial foray, he paired up with psychologist Lawrence E. Williams, now at the University of Colorado Boulder. They invited 41 undergraduate students to visit their fourth-floor psychology lab. During the elevator ride up, the students all encountered a woman carrying an armful of books, a clipboard and a coffee cup. She asked each one to hold her cup, which was either steaming hot or icy cold, while she scribbled something down on her clipboard. Once in the lab, the students read a short description about a fictitious "person A" and then had to rate the warmth of his or her personality. When the scientists analyzed the results, a clear pattern emerged: most of the students who held the hot cup had judged 'person A' to be significantly more generous and caring than those who held the chilly cup. Many similar experiments soon followed, extending the association. ...

"For definitive proof that physical and psychological temperatures are linked, scientists have turned to neuroimaging. 'Neuroscience has confirmed the reality of these phenomena, using much more powerful measurement tools,' Bargh says. These tools have tracked the source of the connection to the insula, a small, pyramid-shaped structure deep within the cerebral cortex. This region plays a role in how much we trust others and how much empathy we feel toward them. A 2015 study, for example, showed that damage to the insula causes people to misplace their trust and be overly naive in some situations but cagey in others. Critically, studies also reveal that the insula is important in temperature perception. In 2010 neurologist Hans Lüders of University Hospitals Case Medical Center in Ohio and his colleagues investigated the cases of five women with intractable epilepsy. In hopes of better understanding their seizures, they surgically placed electrodes in the women's insulae, among other brain structures. They reported that stimulating regions within the insula made these patients experience sensations of warmth in different body parts.

"That same year, working with his colleagues at Yale and Boulder, Bargh conducted an experiment that linked both feelings of interpersonal trust and temperature perception to the insula at the same time. They asked 23 participants to play a game inside a functional MRI scanner. The game required players to hypothetically 'invest' small amounts of money with other people. As they lay inside the machine, some of them held an ice pack for a few seconds; others held a pack heated to a toasty 105.8 degrees F. The scientists observed clear differences in activation within the insula, depending not only on the decisions the players made in the game but also on the temperature of the pack they held. In addition, they noted that participants primed with cold were less willing to invest. ...

"The big question, of course, is why? Why are physical and psychological temperatures linked in the first place? There are two theories, which are not necessarily mutually exclusive. 'One notion is that from birth we've learned that warmth signals the presence of loved ones, so one experience brings to mind the other one,' Inagaki says. 'The second theory is that it's part of our innate system.' For years researchers have explained the connection by way of the first theory, but recent neurobiological evidence gives more weight to the second idea that we have evolved this way. 'For all warmblooded animals, temperature regulation is very metabolically expensive and also required for survival,' psychologist Hans IJzerman of Free University Amsterdam points out. 'But it becomes cheaper when there are others to help us regulate our temperature.' Indeed, animal research has revealed that kleptothermy -- or stealing warmth from others, much as huddled emperor penguins do in Antarctica -- saves metabolic resources. One 2014 study estimated that in a species of Chilean rodents, sharing a cage with just a few other animals lowered an individual's basal metabolic rate by up to 40 percent. Similarly, a 2015 study of vervet monkeys showed that friendly grooming not only helps these animals with tangles and pests, it also renders their pelts better insulated against the cold. If we can save precious energy and feel warmer among others, it makes sense that we would also feel more socially included and trusting when primed with physical warmth. 'Throughout evolutionary time, if you needed somebody else to cuddle with, you needed to know how reliable they were,' IJzerman explains, 'so temperature expectation became involved as a "sociometer" to assess how we think of other people. Despite modern conveniences like central heating, thermoregulation has remained important for how we understand our relationships, which is why in English we refer to emotionally responsive people as "warm" and emotionally unresponsive as "cold."'"