Information Set Theory of Pain: A Short Exploration.

By Greg Mack, ACE-CMES

“Pain don’t hurt.”  

(Patrick Swayze’s character – Dalton – in the movie “Road House”, responding to the doctor about to stitch up his knife wounds after a bar fight, who tells him that inserting the stitches is going to hurt.)

Pain is unfortunately a common occurrence in the human experience. Sometimes it is obvious why an individual reports pain after hitting their finger with a hammer, or cutting himself or herself with a knife. However, pain can also be an elusive concept to understand as sometimes we experience pain with out any obvious cause. Or the strange situation where an individual has had their entire arm amputated and yet report pain the hand of the arm that no longer exists. What is can also be difficult to explain is the circumstance where an individual has a knife sticking out of their head and they do not report any pain?

One of the key problems with understanding pain is that pain cannot be objectively measured and given a numerical value with units, as is typically associated with physical quantities like mass, volume, and length. (1)

So what exactly is pain? Why would Dalton claim “pain don’t hurt?”

Here are some common definitions of the word Pain as a noun:

“physical suffering or discomfort caused by illness or injury” (2)    

“Pain is an unpleasant feeling that is conveyed to the brain by sensory neurons. The discomfort signals actual or potential injury to the body. However, pain is more than a sensation, or the physical awareness of pain; it also includes perception, the subjective interpretation of the discomfort. Perception gives information on the pain’s location, intensity and something about its nature. The various conscious and unconscious responses to both sensation and perception, including the emotional response, add further definition to the overall concept of pain.” (3)

“pain is an unpleasant conscious experience that emerges from the brain when the sum of all the available information suggests that you need to protect a particular part of your body.” (4)

“distressing experience associated with actual or potential tissue damage with sensory, emotional, cognitive and social components.” (5)

“Any sensation that you deem negative and your awareness of that sensation is that you want it to stop.” (6)

“an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” (7)

Historically, and traditionally, pain has been strictly interpreted, by lay people and medical professionals, to be a clear symptom and warning sign of some specific underlying process of disease or due to a physical injury and resulting in, or alerting to the potential of, tissue damage.

Here some interesting observations and questions:

  • Sometimes chronic pain or discomfort occurs in muscles and joints without having injured the area where they’re feeling the pain and discomfort. 
  • Some people who have structural damage to a muscle or joint (as shown by MRI or other imaging) have no pain in the damaged area. Others who have no structural damage in an area point to that area and express that it is painful.
  • Pain is an English word used by an English speaker to verbally share (or in written form – or in American Sign Language with a physical gesture) that they are experiencing a sensation that they don’t necessarily like. What are unusual are individuals who actually seek out pain-inducing events because they apparently like the sensation. (Masochists)
  • People use many words to describe sensations in their body that they don’t like:  pain, discomfort, tightness, soreness, glitches, weakness, and many more.  Why do we choose to describe a particular sensation as “pain” and another sensation with some other word? 
  • Sometimes pain is fleeting: it occurs only occasionally or only when the body is in certain positions or engaging in certain activities. 
  • When an individual describes the emotional loss of a loved one as painful, and another individual describes a cut from a knife as painful are they describing the same thing in terms of their use of the word pain?
  • Why is some pain accompanied by a sense of fear, and other pain described as simply “annoying”? Pain seems to occur across of a variety of qualities. I.e. ache, sting, throb, numbing, etc.
  • Why can there be such an emotional significance (fear, worry, anxiety) to some physical sensations – like pain – but not others? When someone expresses the pain of the loss of a loved one is this the same pain as someone who just fractured a bone?

This article will introduce a concept called Information Set Theory of Pain which offers a broad based explanation to each of these questions.

The Information Set Theory of Pain that states the following: all physical sensation, including the choice to use the word Pain to describe it, is a conclusion of a brain’s moment-to-moment interpretation of the quality and quantity of information flowing within, and throughout, the entire body. This includes all physical sensory, psycho-emotional, and recalled (memory) information.


So, what is it about pain that makes it so tricky?  The reason pain is such a mystery is that pain is a conclusion made by the brain of an individual – which is entirely subjective.  Pain isn’t a “thing” that can be removed or fixed.  Even though someone might be able to point to his or her knee and say, “I feel pain here”, it doesn’t mean your knee is the reason for the pain. Weirdly, the pain is actually concluded in a brain. The brain is presented with information from all the body’s parts, including from within itself, via the nervous and chemical systems, and a particular sensation is simply the brain’s final conclusion about the total information present (which could include information that is absent).  Oddly, where you feel the local sensation isn’t necessarily the source of the information that led to the conclusion – Pain.

The human body is a miraculous vehicle, certainly greater than the sum of its parts.  Part of its genius is its sophisticated setup for communication within itself: the body is one continuous, cohesive system with a built-in mechanism that allows for every part to be aware of, and work with, the other parts to achieve the goal of operating efficiently. The field of engineering and social management refers to this as the “Systems Approach”. (8)

The living body is not simply a set of individual parts, welded, glued, and bolted together, with each operating blindly to the others. Your body grew together from its conception – as a system.  It is impossible to tease out one part from the next without disrupting another part in some way.  The bones grew as the muscles grew. The tendons grew as the ligaments grew. The blood vessels grew as the nerves grew. This inherently connects all of the body’s tissues creating a continuous information stream.

The skeletal muscles and joints are part of this interacting, interconnected, and interdependent system.  The operation and movement of the body is based on extensive collaboration. And that collaboration requires information . . . lots of continuous, high-quality information – from and about each of the body’s regions – communicated to the rest of the system.  Every bodily movement is a whole-body task that requires an internal, whole-body solution.  Brilliant!

When you decide to physically move (or purposely not move), a negotiation occurs between the nervous system and the muscles and joints about how these tasks will be completed; think of it as a “problem-solving session”.  The nervous system receives the information about the intention of your muscles to complete an action, the brain interprets the information and makes the most efficient conclusion it can about how to solve the “problem” based on the information and resources it has available.  How the body feels while completing the task is a product of how well the body “pulled off the task”, or how good the body’s “solution” was.


Did you ever play the game “Telephone” as a kid?  A bunch of kids line up, and the first kid in line whispers a message to the second kid.  The message the second kid heard from the first kid’s whisper gets whispered to the next kid in line, and so on.  Each kid whispers their version of the message down the line, and the game ends when the last kid in line announces the message.  Usually, “Bananas are better than biscuits” ends up something more like “Bandanas are butter and lipsticks”.

Communication within the nervous system works in a similar manner.  Clear, concise, well-communicated information between the muscle-joint system and the nervous system produces a precise, efficient conclusion on the part of the brain, which produces high-quality movement and a high-quality sensation to match.  Just as in the case of our friends and their game of Telephone, a piece of garbled, low-quality communication – or excessive, unnecessary information – or even missing information – will produce a result much different than the brain intended.  The brain’s conclusion about this low-quality information may be reflected in its final analysis.

Have you ever watched a contestant on “Wheel of Fortune” attempt to solve a puzzle for the grand prize?  What happens when the contestant is presented with a complex puzzle and only a few letters are available for the contestant to work with to solve the puzzle?  They may attempt several erroneous solutions to the puzzle, frustration ensues, and eventually the buzzer goes off and the contestant has lost the prize.  They didn’t have enough information to successfully solve the puzzle, or the quality of the information they had wasn’t good enough for the contestant to easily come up with the correct answer within the time limit to win the prize.

Now, what if that contestant was presented with the same puzzle to solve, but this time they had more letters revealed so more information was available in their problem-solving arsenal?  Maybe a critical “z” or “q” was at their disposal.  The contestant now has the information they need to complete the task with ease . . . because the information set they possessed was robust and powerful.  Knowledge is power!

The same holds true for the nervous system.  The more knowledge it has about how to approach a task, the better quality the outcome will be.

Now, let’s apply Information Set Theory to the original questions and issues about pain.  Why would someone feel pain when they are not actually injured?  Why would someone feel pain during some physical movements, or positions, and not others?   Why does pain come in a dizzying array of “flavors”?  Remember: A body’s sensations are a conclusion about a body’s current information state.  The body’s information set changes from moment to moment; the brain’s system of processing and interpreting information is ever adapting and ever evolving.  The body’s ability to devise a high-quality solution to a problem will differ depending on the conditions of the situation, the capabilities of the muscle system under those conditions, and the information the nervous system has available.  If the body system has enough useful information available to solve the problem with high quality, then someone can move well and feel good.  If necessary information is missing, or excessive, or out of context, then the way a body moves and feels will suffer.

Can the Information Set Theory of Pain be useful? 

Yes. But how?

By understanding that changing pain is about changing the information flow.


  • Booth, J., et al, Exercise for chronic musculoskeletal pain: a biopsychosocial approach, Musculoskeletal Care, 2017:1-9, Page 1.
  • The Oxford Dictionary
  • The Free Dictionary
  • Lorimer Moseley PhD – Pain Researcher
  • Williams AC, Craig KD. Updating the definition of pain. Pain. 2016;157(11): 2420–3.
  • Greg Mack, 2009.
  • Derived from a 1964 definition by Harold Merskey, first published in 1979 by IASP in PAIN, number 6, page 250.