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An imperfect measure

By Timothy Cocks Uncategorized 26 Feb 2016

Persistent pain is measured by means of self-report, the sole reliance on which hampers diagnosis and treatment.”

This is the first line of the abstract of a 2013 paper An fMRI-Based Neurologic Signature of Physical Pain from Wager et al.

I think this is quite an extraordinary statement to make – think about it for a moment.

The paper does explain a little further:

“The capacity to effectively report pain is limited in many vulnerable populations (e.g., the very old or very young, persons with cognitive impairment, and those who are minimally conscious).”

But there is also this:

“… but pain is not easy to ascertain. It is primarily assessed by means of self-report, an imperfect measure of subjective experience

How else does one ‘measure subjective experience’ – pain especially?

Can subjective experience even be ‘measured’?

-Tim Cocks



We’ve got an action packed Australian teaching tour happening in 2016. Click on the image below, or the location links, for details:

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Townsville: April 29-May 1 EP & GMI

Canberra: at the Australian Institute of Sport May 3-4 MONIS, May 6-8 EP & GMI

Adelaide: May 14-15 Pain, Plasticity and Rehabilitation

Noosa: June 17-19 EP & GMI

Perth: October 15-17 EP & GMI




  1. jqu33431quintner

    Tim, the answer to your question must be a resounding NO. The experience of pain, as for that of love, cannot be measured. Therefore I do not find the statements you quote to be in the least extraordinary.

    As clinicians, we have failed to understand why what should be a basic function of health professionals – the medical management of people in pain – is not only unsatisfactory in terms of therapeutic outcomes but also frustrating for both the person in pain and their clinician, each of whom may be seeking validation from the other.

    There is now a growing recognition that clinician and the person experiencing pain are both attempting to engage the same aporia (i.e. pain), as well as at the same time attempting to engage with the “other”.

    This is heady stuff!

    1. Thanks John
      I meant “extraordinary” in the sense of “extraordinary that a researcher could state this”, or better, “extraordinary that anyone could think this”. In the interest of brevity, and in the desire for some literary ‘punch’ it seems i have not made my position clear on what i consider to be very dubious and logically preposterous statements.

      My questions were similarly voiced with an air of incredulity which is also probably lost in the format.

      Nevertheless, thank you for your comment, with which I mostly agree, except on the point of finding the statements extraordinary, which I still do in the context described above.

      The authors of the paper seem to have fallen into the trap of thinking that the activity they measure in an individual’s brain (in itself somewhat removed from neuronal activity) *is* somehow equal to the phenomenal content of the individual’s subjective experience, an all too common error.

      On pain as an aporia – “a space and presence that defies us access to its secrets”, Wittgenstein speaking in the Tractatus has always come to mind “Whereof one cannot speak…” with the question following as to whether we must then remain silent on pain if we are unable to access (and presumably speak of) its secrets?

      Thanks again
      My best

      1. jqu33431quintner

        Tim, thanks for your clarification. One day we might get around to discussing the concept of “aporia” in relation to pain.

  2. “… but pain is not easy to ascertain. It is primarily assessed by means of self-report, an imperfect measure of subjective experience“

    I would think that such an overview is valid, along with some of the other quotes from the paper. Unfortunate, but probably true to experience, is how I might describe it. Many might see no consistency or standardisation in regular pain events for similar injuries or infections in different individuals, but, I would be inclined to think that such an overview is, in itself, over-focused on the inconsistent non-standardised narrative which usually accompanies the pain- subsequent individual narrative. The stated narrative will always be vulnerable to conscious manipulation, exaggeration, downplaying, etc etc, but the initial pain event, itself, might seem to be a fairly standard perception for all issues. Is there any argument against the fact that a broken finger, or even a pinprick, hasn’t always registered the same initial pain experience since our knuckle-dragging days ? Any inconsistent interpretations are usually the stuff of variable narratives.

    There’s obviously too much space and licence given to evolving narratives , which themselves are based on variable subjective experiences. That, I think, is what the article is attempting to expose. Especially where there is any operator doubt about the cause of any presented pain experience, and where the operator is unlikely to have had any similar subjective experience, then the only ‘reliable’ indicator is the patient narrative, no matter how badly communicated that might be. That creates an ethical puzzle for the operator, who might have several possible narratives to choose from….whereas the patient only has one. Thus the potential for dissonance in such encounters. Given that a patient with a ‘doubtful’, or undiagnosed, or misdiagnosed, condition might already be nurturing an expectation (sub-text) of disbelief for any advised treatments, there would seem to be cause for concern about ‘mistrust in the patient narrative’ issues arising. For me, where any doubt exists, the patient narrative must take precedence, even when badly communicated. It’s the role of the operator to assist with clarifying the context before any decisions are arrived at.

  3. Is this again another example of experts who confuse nociception with pain? I find it not out of the question that one can measure nociception. However, nociception is not necessarily pain and pain is not necessarily nociception, Would their results look the same, if a well designed non-nociceptive nocebic stimulus was applied? This is an important study that offers some substantial information, I just wish everyone would stick to definitions and understand the difference between nociception and pain.

    1. Hi John
      I think this goes deeper than the problematic nociception/pain conflation. I think this reflects a more foundational issue in ontology and epistemology, and unquestioned assumptions in both. The notion that a brain scan can be more reliable than subjective report about subjective experience, is I think, in many ways rather incredulous!
      Thanks for dropping by

      1. I am not a trained philosopher nor do I know a lot about the fundamentals of ontology and epistemology. What I do know is that both of these processes require the correct use of accurate language (definitions) and a formalized approach to the acquisition, discussion, and explanation of knowledge. I also know that science requires (to the best of our abilities) the consistent use of accurate and accepted definitions of quantities, physical phenomena, and behaviors. Medicine requires accurate use of terminology for communication between professionals and the treatment of patients. Terms, diagnoses, treatments and the words of science and medicine must have real meaning. One of the past and (this article continues to demonstrate) continuing problems of pain medicine/science is that basic terminology has been used in very sloppy and confusing ways. In medicine’s and society’s practice of confusing the process of sensing potential tissue damage (nociception) with the complex processes of determining if the sensory experience “is really dangerous” resulting in the protective response called pain, pain science and pain medicine have led themselves and patients down many non-productive and even harmful pathways. Sloppy thinking and sloppy science is dangerous.

        As I reread the study and particularly look at the conclusion- “It is possible to use fMRI to assess pain elicited by noxious heat in healthy persons. Future studies are needed to assess whether the signature predicts clinical pain.” – I find nothing extraordinary here if we accurately use the appropriate definitions of nociception and pain. Do I think that fMRI should be accurately able to determine nociception? Absolutely just as fMRI can be used to quantify and describe other sensory experiences like sound, vision, taste, and smell. Does this study test pain, as officially defined? No. There was an attempt but it fundamentally ignored the things that it needed to do if it had used the accepted definition of pain.

        At sometime in the future do I believe that fMRI by itself or in combination with other diagnostic studies will be able to accurately see or quantify pain as correctly defined? Absolutely. fMRI and other diagnostic studies are beginning to be able to discern the differences between cacophonous sound and music. In my mind there is not much difference between nociception/ pain and sound/the music of the group “Nine Inch Nails”. Not only do I believe that but I hope that it will be accomplished. It is one thing for the group of us who have treated pain patients to understand their experiences and believe that our patients’ experiences are real. It is a whole different story for the 90% of the medical profession and the lay public. Until there is an objective way to quantify or see pain, as it is correctly defined, pain patients will not get the type of thoughtful and disciplined care they deserve.

        I think that this study made a small step along that pathway. I wish they had been more rigorous in defining pain, however. I think that their study design and result would have been more helpful.

    2. Hi John
      I’m not sure that there is substantial disagreement on many points here. Perhaps you are being contrary in the fine Socratic tradition!

      I’m with you on the accurate use of language and the need for clean thinking – that’s why I think ontology (the study of existence, roughly- what is there to know) and epistemology (the study of knowledge, roughly – how do we know) is so important. I’m not a trained philosopher either, just an interested amateur reader, but I think these fundamental philosophical ideas are unavoidable as one digs deeper into the nature of subjective experience.

      I don’t disagree that science and medicine require accurate knowledge, but I’m not sure what “real meaning” means. This is a slippery slope however and many topics in the philosophy of language continue to be hotly contested so let’s leave this one alone. We can debate Wittgenstein’s beetle in a box (very relevant here though) another time.

      I also agree that sloppy thinking and sloppy science is dangerous.

      But, in the scientific spirit of being rigorous and accurate, I do have some questions.

      1. When you state “Do I think that fMRI should be accurately able to determine nociception? Absolutely just as fMRI can be used to quantify and describe other sensory experiences like sound, vision, taste, and smell”
      1.1 How exactly does fMRI quantify and describe other sensory experiences?
      1.2 What does it mean to ‘accurately determine nociception’? What exactly might we be measuring?
      1.3 And in comparing nociception to other sensory experiences, have you not conflated activity in nerves and the brain (let’s say ‘nociception’) with subjective experience ( call it ‘pain’)?

      2. How do you think the study would have been different if it had done “the things that it needed to do if it had used the accepted definition of pain”. What were these things?

      3. What do you think it would look like to “see or quantify pain as correctly defined?” using fMRI by itself or in combination with other diagnostic studies? What would convince you that you were *seeing* “pain” or “love” or “hate” experienced by another human by looking at test results on a screen? Have we just not gone into fine enough detail with our current scans to ‘see’ these things? Do you think we might be able to ‘see’ them if we can look at individual synapses in real time? What measure might we use to quantify how much pain a human is experiencing by scanning their brain? At what size of voxel might we find lust?

      4. I have no doubt that there is a difference in brain activity when one listens to a cacophony and when listens to a symphony, but does this tell us anything at all about *what it is like* to experience either? I quite like the music of NIN, so I guess one person’s symphony can, of course, be another’s cacophony.

      5. What happens when “there is an objective way to quantify or see pain, as it is correctly defined*” and a person who reports that they experience pain ‘fails’ this objective test? We have this problem right now – an injured worker whose pain is denied by an insurer because “the scans are clear”. I do not share your faith that by moving the anatomical area of interest for the scanning machine from the back to the head will prove to be any better. This (only half tongue in cheek) discussion belongs here –

      *Which is the ‘correct definition of pain’? The current IASP definition (which needs 10 times as many words in the ‘Note’ to clarify the actual definition) states that “Pain is always subjective”. Is it not an oxymoron then to suggest that pain can be quantified in an objective way?

      Where I wholeheartedly disagree with you is with this “Until there is an objective way to quantify or see pain, as it is correctly defined, pain patients will not get the type of thoughtful and disciplined care they deserve.”

      In fact reading this again I couldn’t disagree more. I think it is the very notion that pain, a first person, subjective experience, can be quantified and objectified by a third party, that is at the very heart of the massive problem we have with people experiencing pain, and the only way that people experiencing pain will get the type of thoughtful and disciplined care they deserve is if we (pain scientists, therapists, society as a whole) stop looking for ways to objectively measure *pain* and start to truly listen to the individual in front of us. And I suspect that you did just this over a long and fine career as a physical therapist!

      Does this mean that we stop pain research – of course not, but I think the underlying ontological and epistemological assumptions made by scientists (and therapists, and others) need questioning.

      All just my opinion of course, but if i didn’t respect yours, I wouldn’t bother taking the time to reply!

      Have an awesome day
      My very best

  4. Hi Tim,
    An interesting question……I believe an experience can only be lived, and not measured, by all parties sharing that experience. The interpretation of the said experience will vary depending on the individual’s unique personal and interpersonal ability to truly weigh up their own World at that moment……….How the subject expresses their experience, irrespective of their level of consciousness is their reality………Surely all we are trying to do is help them to have a more comfortable reality……?
    London 🤔

    1. jqu33431quintner

      David, I agree with your comment, but your final sentence leaves me with an unanswered question: what exactly do you mean by a “more comfortable reality”?

    2. Hi David
      Thanks for your thoughts. I agree – the idea of *measuring* subjective experience seems to be rather oxymoronic!

  5. ‘Aporia’ is a perfect description. There’s definitely a secretiveness and mystery about pain which makes it such an interesting topic to study and work with.

    It’s easy to fall in love with the mystery of it all, but there’s a huge risk in doing so. The risk is you adopt a gradualist approach to solving the riddle, and spend your life comfortably avoiding the deep issues. The task is to grab the beast by the horns and SLAY IT.

    IMO, there’s no way pain will be solved without understanding the self/Self – the true nature of man. Throughout history, the truly great healers have ALL expressed this notion in their own unique way.

    Imagine studying architecture and not ever hearing about Frank Lloyd Wright.
    Imagine studying chemitry and never hearing about Curie. And yet this is how Physio is taught – as if there have been no truly great healers throughout the entire human history. The likes of Mesmer, Puyseger, Quimby, Santanelli, Coue, Pearl, Evans, Rogers, Ercikson, etc. … no one has even heard of them. The really sad thing is you can learn more from these guys than from anything you’d get from a modern university.

    1. jqu33431quintner

      “The task is to grab the beast by the horns and SLAY IT.”

      To which particular beast are you referring?

  6. Perhaps it’s not that we can’t measure pain….we do that subjectively all the time, but that we can’t translate our subjective measurements onto a communally accepted scale which allows for all the complexities. A simple 1 to 10 scale falls way short of addressing the possible nuances for each individual level of pain. The

  7. Perhaps it’s not that we can’t measure pain…..we seem to do that subjectively all the time. It’s more that we have difficulty translating the measurement onto a communally acceptable scale which allows for all the nuances of any pain experience. If pain is generally considered to be specific to a definable cause, and it might seem that we intuitively recognise any pain event as raising conscious concern about possible specific injury/infection, then it might well be the nuances of the experience which guide our consciousness towards a reaction, whether that be an induced restraint against conscious interference with a threat, or, the more popular interpretation…. a warning that demands conscious intervention.
    Having a conscious ability to intervene inappropriately, for me, designates conscious intervention ability, itself, as an ‘imminent further threat’, and that inclines me towards thinking that the purpose of any pain event is to restrain possible ill-conceived conscious reactions. There are many praiseworthy means of intervention we use in many threat situations, but there is also the conscious ability to do the opposite….put simply, I have the conscious ability, and freedom, to apply infected dirt to an existing wound. That’s something which the autonomic protective systems would be falling short on if there wasn’t an inherent response mechanism in place, at all times, to contain such a threat. Of course, for any realisation of such an overview, we would have to see consciousness as being sub-dominant to our autonomic protective systems….and that is, apparently, a quantum leap of faith too far for most who ponder these matters.

    Evaluating, or measuring, pain is really an easy subjective exercise. Measuring pain objectively, for science purposes, is another matter. The best we seem able to achieve is a ‘proxying’ of subjective experiences, which is vulnerable to narrative manipulation by all parties. There might even seem to be an inherent conscious resistence to even thinking about another person’s pain experience objectively because it might interfere with our own survivalist expectations. As such, I’m drawn towards the ‘pain neutral’ quote above from David …….”How the subject expresses their experience, irrespective of their level of consciousness is their reality………Surely all we are trying to do is help them to have a more comfortable reality……?”. Compassion, before confusion, every time !

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