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What’s really going on in there?

The skin is a thick, smooth cover for a lot of deep, complex & variable anatomy. Much of what therapists claim to be able to feel in there is based on pride, ideological zeal, good intentions, wishful thinking & active imaginations.

Palpatory Pareidolia & Diagnosis by Touch

Tactile illusions, wishful thinking, and the belief in advanced diagnostic palpation skills in massage and other touchy health care

Paul Ingraham • 15m read

Massage therapists are prone to delusions of grandeur that they can feel (palpate1) things in flesh that ordinary mortals cannot. I had an instructor in massage therapy college — in an allegedly advanced, science-based, and rigorous program — who promised the class that we would learn to detect “a grain of sand through a telephone book, and a hand on the other side of a wall.” A massage website promises you’ll have “x-ray” hands (and be pain-free!) after just thirty days of practicing hair-feeling.2

In the flakier regions of the world of massage, the palpation pretension often blends smoothly with an earnest belief in “energy fields” and extrasensory perception. When that teacher spoke of detecting hands through walls, she was talking about picking up on auras and such, not infrared radiation or vibrations. Jedi palpation tricks!3 Bizarre ideas are quite common in massage therapy.4

Knowledge of anatomy, and skill in feeling it, is real and valuable. I can’t feel a grain of sand through a wall, but after years of practice I can definitely find your infraspinatus muscle. In the dark, in about three seconds. Through a thick towel. However, therapists do often fool themselves into thinking they are feeling things under their hands that are not actually there, or things that might be there but cannot possibly be detected with any reliability. They do this because of pride, ideological zeal, good intentions, wishful thinking, and active imaginations.

This is palpatory pareidolia. Illusions can be tactile as well as visual.

Pareidolia: perceiving the familiar in the random

Pareidolia is a type of illusion or broken perception in which a vague or obscure stimulus — i.e. subtle textures under your skin — is perceived as if it was actually clear and distinct. It is both a source of illusion, as well as our impressive and useful ability to make meaning out of glimpses and shreds of sensation. Pareidolia is:

Religious pareidolia examples are so common and culturally significant through history that they have their own name: simulcra. They can seem quite neurologically glitchy.5 In the last few decades, a lot of religious feelings have been transplanted from organized religion into disorganized spirituality and alternative medicine, resulting in many striking similarities between Jesus freaks and new age flakes.

Early in my career as a massage therapist, I encountered my first dramatic example of this, while I was setting up a small office with a colleague. Fresh out of school, I was not yet much of a critical thinker, and was initially charmed and unalarmed by her ideological zeal for alternative medicine. However, our deal fell apart as her susceptibility to delusion became clear: she was wringing spiritual significance out of nearly everything around her. I remember feeling the first chill of deep concern when we were on the street and she spent a few minutes explaining to me how a glimpse of an advertisement on a bus was a “bad omen” for our business plans. I killed the deal when she “saw” an evil pattern in the numbers on our new office door, and demanded that we move to another office.

That’s what I mean by “glitchy.” And it was inevitable that she would inject such bizarre interpretations into her clinical interactions! What “omens” would a massage therapist like this detect in your tissues?

For every glaring case of irrationality like this, there are many less obvious examples. It’s not a matter of opinion that the brain is easily confused in this way: pareidolia is a fascinating richly neurological phenomenon, the product of a number of well-known cognitive and sensory distortions, and it has many familiar cousins. Many illusions are highly repeatable.6

Pareidolia in manual therapy

Humans are talented at perceiving what we want to perceive and expect to perceive. This is a firm premise of this article. Over-interpreted perception has always been a huge problem for empiricism. The brain is just fantastically good at making up patterns and filling in blanks.

And palpation in a therapeutic context provides some rich opportunities for pareidolia. It is responsible for who-knows-how-many declarations of “tightness,” for instance. Here are several other candidates for illusory palpations, all common in massage therapy, chiropractic, and osteopathy:

In each case, the alleged phenomenon may or may not be a real thing, while the perception remains plagued by false positives. For instance, cerebrospinal fluid is real, and it does circulate! But no therapist can reliably detect that rhythm;9 if they could, it would nearly be worthy of Randi’s million-dollar prize, and I’d bet against it in a fair test just as confidently as I would bet against dowsing or psychic predictions. Fascial restrictions might be real, and maybe even quite easy to feel, but many alleged detections are certainly wrong (and I’m also doubtful that they are clinically interesting in any case).

N-rays: an incredible historical example of pareidolia

Abstract image that looks like a white sun in a dark blue sky emitting about a dozen slightly curved rays that extend all the way out to the edge of the image. It looks a little like a turbine, but the main impression it gives is of radiating energy.

While listening to one of my favourite podcasts, Caustic Soda — now defunct, alas, but their archives are still available — I came across a fascinating historical example of the pareidolia phenomenon dialed up to 11: the N-rays debacle. In fact, it may be one of the biggest pareidolia bloopers in history. Joe Fulgham tells the story well, and you should listen to the episode.

In a nutshell, in 1903 a French scientist, Blondlot, got himself worked up over a new form of radiation. He was certain he could see it. He couldn’t. It was 100% wishful thinking. But this kind of mistake happens all the time in science and life.

What really amplifies the example is that so many other scientists jumped on the bandwagon and eagerly shared Blondlot’s delusion. That is a bit more unusual in science, specifically because science defines itself as a profession that carefully checks its facts. Fortunately, the N-ray delusion did not last long, because many other scientists called foul from the start. The “immune system” of science attacked the disease, and N-rays were destroyed.

But the story shows that pareidolia is powerful, and no one is safe from its disortions. It literally happens to the best of us. The measure of an intellect (or a profession) is not immunity to pareidolia, but the humility required to doubt your own perceptions. (Humility and the knowledge of how flawed perception is.)


… people informed of the biases and pitfalls of their unconscious brains are better at using their conscious minds to overrule them.

book review in The Economist, of Subliminal: How Your Unconscious Mind Rules Your Behaviour, by Leonard Mlodinow

Finding the pain: professionals struggle to identify by touch alone which side of the body hurts

A study showed that two professionals, rather disappointingly, could not even identify the side of the body that back or neck pain was on by feel alone.10

Maigne et al tested two physicians with training in manual medicine to see if they could detect the painful side by feeling for tension in the spinal muscles. In almost two hundred patients, they identified the correct side of 65% of lower back pain and 59% of neck pain — barely better than chance. (And, if they couldn’t do it, most massage therapists would probably fail the same test — despite our legendary reputation for zeroing in on tissue problems with uncanny accuracy.)

The results are obviously underwhelming. Although they did a little better than just guessing, the results suggest that it’s difficult even for expert examiners to detect the location of neck and back pain by feel. As well, they were only attempting to detect the side of pain — kind of the palpation equivalent of hitting the broad side of a barn in target practice. Imagine how much worse their performance would have been if they had to identify the location more precisely, or if the pain could have been anywhere or nowhere. So they barely passed the easiest possible test, and probably would have failed a harder one and done no better than guessing.

An obvious weakness of the study is that only two examiners were tested. More and possibly more experienced examiners might have yielded different results. But one would still hope for better than this from anyone with any training and experience at all.

And so what? Ironically, this was actually an understandable and unimportant failure. The ability to detect the painful side by feel alone is difficult for reasons that make sense, and are consistent with what we actually know about how neck and back pain work — namely, they don’t cause obvious, consistent changes in tissue texture and they correlate poorly (really barely at all) with obvious structural problems. Detection of nonexistent, subtle and unreliable signs is not actually an important diagnostic skill.

But I’m afraid it all does rather fly in the face of the popular mythology that therapists can zero in on tissue problems with uncanny accuracy.

Bonus semi-relevant perception thing:
He’s dead, Jim! Or maybe I just can’t find a huge throbbing artery!

This article is about how difficult it is for human beings to accurately perceive tissue textures that may be subtle, fleeting and deeply buried. But it turns out we can’t even get the most obvious things right: not even when they pulsate powerfully right underneath the skin, all day, every day, always in exactly the same spot.

My mother is a fitness instructor in downtown Vancouver. She upgrades her first aid skills every year, and every year the methods and best practices change a little. In 2012, she learned that taking a carotid pulse was out! Obsolete. Kaput. Why? The explanation is a bit shocking.

People can’t find it. (Sort of. I’m exaggerating a little for effect — but only a little.11)

Most people simply cannot reliably find a pulse, and — this is important — even after being taught. We’re not talking about random people on the street, but people who have had first aid training, possibly even regular first aid training. So St. John’s Ambulance has dropped it from their training.

I shouldn’t have been surprised by that, but I was. Humans apparently aren’t very good at much of anything without a bunch of practice and related knowledge, and even the simplest things in medicine can really stump people.

Tinker With Your Ticker  0:15

Don’t get me wrong

Massage therapists do have exceptionally extensive sensory experience with soft tissue. Just because perception is difficult doesn’t mean people can’t get good at it — amazingly good, like the blind reading with their fingertips, or a blindfolded painter who can tell you what type of paint you’ve dipped her brush in. Perhaps some of the most experienced therapists know muscle texture like that. The reality of palpatory pareidolia does not mean that people cannot still accomplish sensory marvels.

However, even that does not make us immune to error, nor can we know what most subtle textures mean, even when we perceive them accurately. It’s not practical, clinical knowledge. Pretending otherwise is too common, and it is the thin edge of a wedge of arrogance.

Palpation is an unreliable art, not a science, and manual therapists and patients should be aware of this and cautious about making or believing any claim based on it.

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About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of ScienceBasedMedicine.org for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter., or subscribe:

Notes

  1. Palpation is diagnosing and assessing by feel. Palpation should not be confused with palpitation, which is an awareness of the beating of the heart.
  2. You too can learn to feel a hair! Alert reader Michael B. sent me this absurd example of delusions of palpatory grandeur, How To Get Out Of Pain In 30 Days. There’s a million crappy miracle cure sales pitches out there, of course, but this one revolves around near-magical powers of palpation in particular: “Now, close your eyes and comb over the paper until you find the hair; continue to drag the hair underneath your finger and around the paper until you lose it. Repeat for 15 minutes/day. Within 2-4 weeks, you’ll have an incredible sense of touch.” Yes, that’s all it takes to get “x-ray hands”: hair rubbing. And if you believe that, I’m having a bridge sale.
  3. Here’s a typical example: in his book Like Chiropractic for Elephants, chiropractor Dr. Rod Block claims to have “an uncanny sensory perception that allows him to connect with the person or animal he comes in contact with … . It is then that the animal senses his intention of wanting to help and releases inhibitions that allow discovery of where the root cause of the pain, stress or pressure may exist … . The doctor uses his uncanny ability to tune into the root cause of animal states of disease without the use of drugs or surgery.”
  4. Ingraham. 💩 Massage Therapists Say: A compilation of more than 50 examples of the bizarre nonsense spoken by massage therapists with delusions of medical knowledge. PainScience.com. 11683 words.
  5. The part of the brain that assigns meaning to things can get dialed up to 11 by religiosity, resulting in some really absurdly over-interpreted perception, and basically seeing God in almost anything. (See StuffThatLooksLikeJesus.com for many entertaining examples.)
  6. Theinvisiblegorilla.com [Internet]. Chabris C, Simons D. The Invisible Gorilla; 1999 [cited 20 May 13]. PainSci Bibliography 54561 ❐

    Description and video of a classic mind-blowing psychology experiment that demonstrated “inattentional blindness” — such as not noticing a gorilla walk through a group of people you’re watching.

    Chabris & Simons book is excellent read: see The Invisible Gorilla.

  7. Lucas N, Macaskill P, Irwig L, Moran R, Bogduk N. Reliability of physical examination for diagnosis of myofascial trigger points: a systematic review of the literature. Clinical Journal of Pain. 2009 Jan;25(1):80–9. PubMed 19158550 ❐
  8. Myburgh C, Larsen AH, Hartvigsen J. A systematic, critical review of manual palpation for identifying myofascial trigger points: evidence and clinical significance. Arch Phys Med Rehabil. 2008 Jun;89(6):1169–76. PubMed 18503816 ❐
  9. Wirth-Pattullo V, Hayes KW. Interrater reliability of craniosacral rate measurements and their relationship with subjects' and examiners' heart and respiratory rate measurements. Phys Ther. 1994 Oct;74(10):908–16; discussion 917–20. PubMed 8090842 ❐
  10. Maigne JY, Cornelis P, Chatellier G. Lower back pain and neck pain: is it possible to identify the painful side by palpation only? Ann Phys Rehabil Med. 2012 Mar;55(2):103–11. PubMed 22341057 ❐ PainSci Bibliography 54321 ❐
  11. A lot of people can find the carotid pulse, but on average people cannot find it quickly or reliably enough for the purposes of first aid — that is, they particularly don’t know enough to quickly reach a decision that a patient is truly pulseless. See Dick et al., 2000: “Recognition of pulselessness of the carotid artery by rescuers with basic cardiopulmonary resuscitation training is time-consuming and highly inaccurate. Although the carotid pulse check needs to be taught, its importance in the context of layperson basic life support should be de-emphasized.”

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