Courtesy of Ross Pomeroy @ Real Clear Science:
As the heart of the United States braces for a wicked cold snap next week, there’s also chilling news coming out of the journal PLoS ONE. On Wednesday, neuroscientists from the United Kingdom reported that cold is contagious. Yes, just looking at someone who’s shivering or experiencing frigid temperatures can cause parts of your own body to become colder.
For the study, the researchers had 36 participants sit in a temperature-controlled room and watch videos of actors placing one of their hands in either visibly steaming water, ice water, or neutral still water. Each subject watched ten total videos, four each featuring warm and cold water with different actors who used either their left or right hand, as well as two control videos. All of the videos lasted two minutes.
Throughout the process, the researchers closely monitored subjects’ heart rates and hand temperatures. While watching the warm and neutral videos did not produce any changes in subjects’ hand temperature, watching the cold videos caused a small, but unmistakable drop. The temperature of subjects’ right hands fell by an average of 0.1 degrees Fahrenheit, and the temperature of their left hands fell 0.4 degrees. There was no change in heart rate.
Why didn’t the warm videos prompt a warming effect? The authors suggest that the warmth of the water, as indicated by the steam, may not have been as visible. On the other hand, the ice water was clearly frigid. They also note a prior review which showed that it’s easier to elicit a decrease in skin temperature than an increase.
The current study presents further support and adds a physical condition to emotional contagion, the tendency for two individuals to mimic each other’s expressions and emotional states. Emotional contagion is thought to be mediated by mirror neurons, brain cells that fire both when an animal peforms a certain action or observes that action. The study also broadly substantiates an extreme case of human temperature fluctuation documented in 1920 by scientist J.A. Hadfield, who worked with a patient who was able to selectively adjust their right and left hand temperature by as much as 5 degrees Fahrenheit through suggestions of heat or cold.
Source: Cooper EA, Garlick J, Featherstone E, Voon V, Singer T, et al. (2014) You Turn Me Cold: Evidence for Temperature Contagion. PLoS ONE 9(12): e116126. doi:10.1371/journal.pone.0116126