Pain is really complex. It helps protect us from something potentially dangerous that might result in damage or harm to our body. Pain is also weird and not at all straightforward. Most of us have heard stories about amputee’s still feeling pain in a missing foot, or the time you didn’t feel a cut on your leg until you looked down at it.
Pain is dependent of many factors, not just the information coming from the tissues such as bones, joints and muscles. A clear example of this is a study conducted in 2007 by L. Moseley and A. Arntz. In this experiment, healthy and pain free participants had a -20 degree piece of metal placed on their skin. At the same time, they were shown a red light in one trial and a blue light on the second trial. They were then asked to rate their pain from 0-10 and also the temperature of the metal piece from 0-10.
Interestingly, there was a significant difference in pain ratings between the two scenarios even though the stimulus on the skin (-20 degree piece of metal) was the same. The participants rated the pain higher when they saw the red light and less when they saw the blue light. Even more intriguing was that the participants stated that the temperature felt hot when they saw the red light.
So how can this be happening? Pain is a result of a lot of information being evaluated by the brain at one time. This includes information from our tissues, our other senses, as well as information from brain areas related to beliefs, meaning, memory and future planning. All these factors come together for the brain to essentially ask “how much danger are we in here?” From this study, we can conclude that in our society and culture, the meaning of the colour red is dangerous and hot, whilst the colour blue is associated with calm and cool. The brain is taking this information into consideration and in this experiment produces a higher pain output for the red light, which it concludes to be more dangerous.
Belief and meaning are key factors when it comes to pain and we need to recognize how much these are influencing our pain presentation. Anticipation and fear also have a role to play in how we experience pain and both need to be addressed especially as pain persists where the relationship between tissue damage and pain becomes less precise. Research is consistently demonstrating that the more we know about pain, the more effective and structured the rehabilitation can be to improve one’s condition.
Moseley L & Arntz A (2007) The context of a noxious stimulus affects the pain it evokes. Pain. 133(1-3) 64-71
Chris Davies is in clinic Tuesdays and Saturdays