How many dots can you see in this image? It might tell you something about your back ache.
Before reading have a look at the image below and count how many dots you can see.
There are 12 dots but because some will always be in the periphery we can’t ‘see’ them all at once. The light hitting the back of our eyes is only one piece of what goes into creating the visual image we see in our ‘mind’s eye’.
The highest concentration of light receptors is in a small area in the centre of our retina called the fovea. The eye is supplying the brain with much less information about the periphery of our visual field. Our brain is able to create a full image based both on the information from the eye and what it predicts should be there based on experience. Based on past experience and the pattern of solid lines the brain predicts solid lines and so it creates solid lines, we cannot see all the dots.
This is analogous to all of our sensory experiences, including pain. Information the brain receives from the body is only one of many pieces of information the brain uses to predict threat and create painful sensation to protect us. It is not always accurate and can be over protective. Just like in the image where lines don’t always mean lines, pain does not always mean damage.
A (much!) more in depth paper on the imprecision hypothesis of pain here:
http://www.bodyinmind.org/…/Moseley-Vlaeyen-Beyond_nocicept…