People can feel pain just by witnessing others in agony, according to a new study.
A Monash University study into the phenomenon known as somatic contagion found almost one in three people could feel pain when they see others experience pain.
It identified two groups of people that were prone to this response - those who acquire it following trauma, injury such as amputation or chronic pain, and those with the condition present at birth, known as the congenital variant.
Dr Melita Giummarra, from the School of Psychology and Psychiatry, said in some cases people suffered severe painful sensations in response to another person's pain.
"My research is now beginning to differentiate between at least these two unique profiles of somatic contagion," Giummarra said.
"While the congenital variant appears to involve a blurring of the boundary between self and other, with heightened empathy, acquired somatic contagion involves reduced empathic concern for others, but increased personal distress.
"This suggests that the pain triggered corresponds to a focus on their own pain experience rather than that of others," said Giummarra.
Most people experience emotional discomfort when they witness pain in another person and neuroimaging studies have shown that this is linked to activation in the parts of the brain that are also involved in the personal experience of pain, researchers said.
Giummarra said for some people the pain they "absorb" mirrors the location and site of the pain in another they are witnessing and is generally localised.
"We know that the same regions of the brain are activated for these groups of people as when they experience their own pain. First in emotional regions but then there is also sensory activation. It is a vicarious - it literally triggers their pain," Giummarra said.
Giummarra has developed a new tool to characterise the reactions people have to pain in others that is also sensitive to somatic contagion.
