Wednesday December 23 2009
Seeing others in pain can activate areas of the brain involved in pain
“Some people really feel your pain,” reported The Daily Telegraph. It said that “one in three people actually feel physical discomfort when they see someone else in agony”.
This news story is based on research that investigated how seeing images of others in pain can cause some people to report mild pain-like sensations. It also measured whether these sensations are associated with a change in activity in the areas of the brain that control our experience of pain.
This study shows that some people can experience pain vicariously, and that these experiences are accompanied by an increase in the activity of “pain regions” of the brain. Although it was a small and preliminary study, it may contribute to the understanding of the processes in the brain that underlie the sensation of pain in general.
Where did the story come from?
This research was carried out by Dr Jody Osborn and Dr Stuart Derbyshire at the University of Birmingham. It was funded by the Hilary Green Research Fund, and published in the peer-reviewed medical journal Pain. This study was accurately reported by The Daily Telegraph.
What kind of research was this?
In this controlled trial, the researchers examined the science behind anecdotal reports of “pain without injury, and the apparent ability of at least some people to share the sensory component of an observed injury or touch”. Specifically, they wanted to test whether normal subjects would experience pain when observing another person in pain.
What did the research involve?
The researchers recruited 108 undergraduate psychology students with an average age of 23 years.
The participants were shown seven images and three movie clips of people in pain, such as breaking a leg or receiving an injection. Immediately after viewing the pictures or movies, they were asked whether they felt any sensation of pain in their own body. It was emphasised to them that any feelings of disgust or unease should not be recorded as pain.
The participants reporting that they felt pain were asked to rank its intensity using a visual analogue scale. This scale runs from zero to 10, signifying no pain at all to the worst pain imaginable. They were also asked to describe the type of pain, such as throbbing, shooting or sickening, and where on their body they felt it.
All of the participants were also asked to rank their disgust, sadness and fear reactions to the images, and their empathic feelings towards the person in the image.
The researchers then selected 10 people who had felt pain from seeing the images, and 10 people who hadn’t (four men and six women in each group). These participants’ brain activity was measured using functional magnetic resonance imaging (fMRI) while they were presented with seven new pictures of people experiencing similar levels of pain to the initial screening. As before, they ranked their experiences of pain and the emotions that the images evoked in the fMRI scanner.
What were the basic results?
Of the 108 participants, 31 reported a pain sensation when they saw the images. All 31 described feeling the pain in the same location as that observed in the picture. The most common description of the pain was “tingling”.
The image that generated the highest ranked pain rating was an athlete with a broken leg, for which the average pain rating was 3.7. The lowest average pain rating (0.5) was in response to a picture of a man who had fallen off his bike.
The emotional and empathic response of the people who felt pain was compared to those who had felt no pain. The researchers found that those who “felt pain” ranked their feelings of disgust, fear and unpleasantness higher on a 0-10 scale than those who did not. The felt-pain group also ranked their feelings of empathy higher. There was no difference between the two groups in the intensity of reported sadness. There was no correlation between the pain intensity in the felt-pain group and the intensity of their emotional response.
The fMRI experiments demonstrated that both groups showed increased activity in brain areas associated with emotion, but that the felt-pain group also showed more activity in the area of the brain that processes sensations from the body (brain regions called S1 and S2).
How did the researchers interpret the results?
The researchers concluded that a minority of normal subjects “share not just the emotional component of an observed injury but also the sensory component”. They say that regions of the brain known to be involved in pain are activated, and that “these regions are not just passively recording injury or threats to tissue, but are actively generating painful experience”.
This study found that for some people, seeing another person in pain can induce a mild pain sensation. It also found that these people also have a heightened emotional and empathic response to other people’s physically painful experiences. This research was well carried out. However, it has limitations that influence its interpretations:
- The participants were all psychology students who may have differing socioeconomic and educational backgrounds that are not representative of the population as a whole.
- The method of reporting pain and emotion (a visual analogue scale) is a subjective measurement. It can yield highly varied results from different people, and even from the same person if used at different times.
- The study was small and looked at a number of possible outcomes and correlations. Compared with a larger study examining fewer outcomes, it is more likely to have found results that may have arisen through chance.
This study shows that some people can experience pain vicariously. Although it is a small and preliminary study, it is a useful contribution to the understanding of the processes in the brain that underlie the sensation of pain in general.