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What’s really going on in there?

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

Palpatory Pareidolia

Sensory illusions, wishful thinking, and palpation pretension in massage and other touchy health care

2,500 words, published 2012, updated Oct 18th, 2013
by Paul Ingraham, Vancouver, Canada bio
I am a science writer, the Assistant Editor of ScienceBasedMedicine.org, and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I’ve written hundreds of articles and several books, and I’m known for sassy, skeptical, referenced analysis and a huge bibliography. I am a runner and ultimate player, and live in beautiful downtown Vancouver, Canada. • full bioabout SaveYourself.ca

Massage therapists in particular 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 college2 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 website promises you’ll have “x-ray” hands (and be pain-free!) after just thirty days of practicing hair-feeling.3 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!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 certainly can 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:

“Golden retriever? What golden retriever? All I see is a cloud!” Imagine if you really couldn’t see shapes in clouds — what a sad, boring life that would be. Pareidolia can be highly functional and entertaining. But we also need to know how it can fool us.

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. 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.

See what I mean by “glitchy”? It was inevitable that she would inject such bizarre interpretations into her clinical interactions! What “omens” would she have detected 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: 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

We are talented at perceiving what we want and expect to see. Over-interpreted perception has always been a big 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 it. 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 (and chiropractic, and osteopathy, and so on).

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 certainly real, and it does indeed circulate! But no therapist can actually detect that rhythm reliably; if they could, it would nearly be worthy of Randi’s million-dollar prize, and I’d bet against it in a fair test as confidently as I would bet against dowsing or astrology. Fascial restrictions may well be real, and some may even be quite easy to feel, but many alleged detections are certainly wrong (and I’m skeptical that finding them matters).

N-rays: an incredible historical example of pareidolia

ZOOM

While listening to my favourite new podcast, Caustic Soda, 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. It actually does happen to the best of us. The measure of an intellect (or a profession) is not immunity to pareidolia, but the having the humility and savvy to doubt your own perceptions.


…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: massage therapist struggle to identify by touch alone which side of the body hurts

An imperfect but adequate recent study showed that massage therapists, rather disappointingly, could not even identify the side of the body that back or neck pain was on by feel alone7 — despite our legendary reputation for zeroing in on tissue problems with uncanny accuracy. Maigne et al tested two (presumably expert) examiners 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 — only slightly better than chance.

An odd anomaly occurred in the difference between the left and right side: the examiners were more accurate on the right side with back pain, but better on the left side with neck pain.

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. Expert examiners barely passed the easiest possible test, and probably would have failed a harder one.Imagine how much worse their performance would have been if they had 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 therapists were tested, and so the results are inconclusive. One would still hope for a better detection, though, even from less skilled therapists.

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.8)

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 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 not 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.

About Paul Ingraham

I am a science writer, former massage therapist, and assistant editor of Science-Based Medicine. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook and Google, but mostly Twitter.

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. BACK TO TEXT
  2. Massage therapy training in British Columbia, Canada, is unusually rigorous compared to most places in the world. When I trained, the requirements included a 3000-hour training program, an internship, and some very challenging certification exams. For more information, see Massage Therapy In British Columbia (Canada): Training, credentials, and the state of the profession of massage therapy in this province. BACK TO TEXT
  3. 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. BACK TO TEXT
  4. Here’s a typical example: in his book Like Chiropractic for Elephants, chiropractor Dr. Rod Block claims to have “an uncanny touch 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.” BACK TO TEXT
  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.) BACK TO TEXT
  6. The Invisible Gorilla. Chabris et al. theinvisiblegorilla.com. 1999.

    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.

    BACK TO TEXT
  7. Maigne et al. Lower back pain and neck pain: is it possible to identify the painful side by palpation only? Ann Phys Rehabil Med. 2012. PubMed #22341057. BACK TO TEXT
  8. 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.” BACK TO TEXT