Watching another person shiver can cause our own temperature to drop, scientists have found.
Volunteers who watched videos of actors plunging their hands into ice-cold water experienced a simultaneous drop in the temperature of their own hands.
Neuroscientist Neil Harrison, from the University of Sussex, said watching others experiencing extreme conditions triggers feelings of empathy.
“We believe that this mimicry of people’s bodily response helps us understand how they are feeling,’ he said.
“Mimicking another person is believed to help us create an internal model of their physiological state which we can use to better understand their motivations and how they are feeling.
“Humans are profoundly social creatures and much of humans’ success results from our ability to work together in complex communities – this would be hard to do if we were not able to rapidly empathise with each other and predict one another’s thoughts, feelings and motivations.’
It’s believed that ‘mirror neurons’ in the brain are behind the phenomenon.
“Mirror neurons found in very specific parts of the brain are known to fire when we perform an action or observe a similar action in others – it has been proposed that more general mirror properties may also exist across many other brain areas,’ said Dr Harrison.
Dr Harrison first wondered about the impact of the temperature of others after watching the Atanarjuat: The fast runner about the Inuit peoples of the Canadian arctic.
“It has an amazing scene where the lead actor gets chased naked across the frozen arctic – its impossible to watch without feeling cold yourself,” said Dr Harrison.
For the study, which was published in the journal PLOS One, the researchers asked 36 participants to watch eight videos that depicted actors with one of their hands in visibly warm or cold water.
Each video began with the actor sitting in front of a transparent container partially filled with water.
For the four warm videos, the first 40 seconds showed the actor gradually adding hot water from a steaming kettle into the container, checking the temperature of the water every few seconds. The actor is then shown with their hand immersed in the water for a further two minutes and 20 seconds.
For the cold videos, the actor does the same, but fills the container with a bag of ice instead.
Four control videos with the actors’ hand in front of a tank of room temperature water were also shown.
None of the actors’ faces could be seen and the temperature of the room was kept at a constant 21 degrees C.
The researchers monitored the participants’ hand temperature throughout and found that when they watched the actors put their hands in the iced water, their temperatures dropped by a small, but statistically significant, amount: 0.2 degrees C (0.4F) in their left hands, and 0.05 degrees C (0.1F) in their right.
There was no significant change in temperature when the participants watched the control videos and the warm water videos.
Dr Harrison said: “Though we didn’t see a significant change in participants’ own hand temperature when they viewed the warm videos, we think that this is probably because the warm videos were less potent – the only cues that the water was warm was steam at the beginning of the videos and the pink colour of the actor’s hand (whereas blocks of ice were clearly visible throughout the duration of the cold video).
“There is also some evidence to suggest that people may be more sensitive to others appearing cold than hot. Why this may be the case is currently unclear.”