Watching somebody shivering on television can induce the same type of physiological response as braving the icy elements in person, according to a research study conducted by scientists at the University of Sussex.
The recent study demonstrates that humans are vulnerable to "temperature contagion" as body temperatures in volunteers dropped significantly after watching videos of people placing their hands in cold water.
"We were surprised, but also excited by the findings," University of Sussex Researcher and Neuropsychiatrist Dr. Neil Harrison said.
The research, conducted by scientists working at the Brighton and Sussex Medical School, was published in the journal, PLOS ONE, in late December.
"Prior to the study, we were struck by how movies showing people exposed to cold environments, particularly when the person observed is naked, can evoke a powerful feeling of coldness in the viewer," Harrison said, citing the film, "Atanarjuat: The Fast Runner," as a key example.
"It's impossible to watch without feeling cold yourself," Harrison said. "We were curious to know whether this feeling was associated with an actual drop in temperature in the viewer as would be predicted by theoretical models of empathy."
While the exact mechanism behind the volunteers' responses is still unclear, humans tend to mimic one another's emotional facial expressions, body posture and even some components of speech during social interactions, according to Harrison.
The current understanding is that humans mimic others to create an internal model of their own physiological state, which can be used to predict others' thoughts, feelings and behavior.
"It would appear that we are doing this across a wide range of different parameters, typically without conscious awareness," he said, adding that this helps us to intuitively understand or empathize with others.
While many of these types of interactions are widely considered to be under a person's control, Harrison said, the team was curious if a non-emotional, physiological response could occur.
"Our current findings do suggest that this marked human tendency to mimic does also extend to 'non-emotional' settings like simply seeing someone else's hand in cold water and to physiological responses like control of the temperature of different parts of our body that we don't ordinarily have volitional control over," he said.
Maintaining a core body temperature is critical to life in many animals including humans, Harrison said.
There are two primary mechanisms through which core body temperature is maintained. One way the body increases and decreases the production of heat is through the breakdown of food and body fat. Another way bodies control the loss of heat is by regulating blood flow to areas of the body like the hands and feet.
"Our bodies have dedicated cool and warm sensitive neurons that are sensitive to changes in environmental temperature," Harrison said.
If a reduction in environmental temperature is detected, the body will decrease blood flow to the periphery to maintain core body temperature or vice versa if an increase in environmental temperature is detected.
"These changes are done automatically, generally outside of conscious awareness, and mainly controlled by the hypothalamus," he said. "However, the basic machinery is also sensitive to 'top-down' influences."
Core body temperature can also be regulated to some degree by higher brain areas like the cortex. Cognitive processes can influence our peripheral body temperature either subconsciously or even consciously, though most of us are not aware of this ability, Harrison added.
"Most can be trained to regulate peripheral body temperature to some degree by techniques like temperature biofeedback, hypnosis or mental imagery," he said. "We believe that the mechanism at play during temperature contagion utilizes these top-down pathways, though exact mechanisms are currently unclear."
While a feeling of cold was observed in the volunteers, it is likely the same type of response can be exhibited toward heat.
"Our warm videos were probably less potent than the cold ones," Harrison said.
In the cold videos, ice was clearly seen floating on the water throughout the video. However, in the warm videos shown to the volunteers, steam coming off the water was only seen at the beginning.
"Future studies would benefit from using slightly more potent warm videos," he said.