The Fatal Heuristic

Barrett L. Dorko, P.T.

There's a giant dictionary in the library here in Cuyahoga Falls, and sometimes I go there to find out what a word really means. This book is so big that it stands open on its own little table, saving patrons from the dangerous task of tipping it from a shelf. I'm personally a big, strong Slovak, but even I appreciate the table and the fact that I only need to lift a few of these large pages at a time.

I went to this book a few days ago to look for a word that has haunted my occasional reading about reasoning and problem solving. The word is heuristic.

I don't think anyone would argue if told the polio epidemic formed a large part of our profession's early identity and prestige. I remember it prominently mentioned in a recruiting film for P.T. school that I was shown in the early seventies. I sometimes wonder at how difficult a job it must have been back then, and if I would have been able to face the clinic each day without despairing. Those who stuck it out, who actually went willingly into the wards of immobile, terrified victims of the disease in order to help are often honored for this, and the respect shown them should always remain within our ranks.

Having said that, I want to return to the meaning of heuristic, and its place in the formation of a theory that drives much of our practice today.

Heuristic comes from the Greek "heuriskein," meaning "to discover." A heuristic is a problem solving technique that leads to conclusions that are based on appearance rather than careful investigation. They are short cuts that allows us to proceed rapidly from observation to action and we use them all the time. For example, when I see a certain movement in a patient I often form a conclusion about what is wrong and proceed with care that probably should include more testing beforehand.

Sometimes a new patient in the waiting room appears bright or slightly dull, angry or pleasant, happy or depressed. I proceed to relate to them as if I knew, and find I am precisely wrong. Not only that, but my bias makes it hard to see how things really are once my initial conclusions are drawn. Heuristics often mislead me, but without them my movement in any direction would be very slow.

Searching for clues about postural control when physical therapy was in its infancy must have been at once exciting and terribly frustrating. True research was scarce and it fell to the clinicians to discover what worked and then to reason backward to make sense of technique. But whatever else polio produced, it provided a vast laboratory full of patients with weakness. The postures they adopted provided ample evidence that muscular strength was correlated to a joint's resting position and therapists found that given enough functioning neural tissue, active exercise could alter an undesirable posture.

The big book in the library also has this to say about heuristics; it says that they provide aid or direction but are otherwise unjustified, it says they are assumptions or dubious assertions.

Now the hard part. It appears to me that the therapists that emerged from the epidemic with the assertion and conviction that muscular strength was correlated to posture had made an error, and that error was the result of heuristic reasoning. The error is perpetuated, I think, by both a lack of scientific rigor in our ranks, and a powerful meld of professional identity and reverence for those (now elderly) who built the schools we attended.

Consider this. Studies published in 1987 and 1990 in the Journal of the American Physical Therapy Association demonstrated that muscular strength about the pelvis and shoulder was unrelated to the posture of either region. Another study funded by The Foundation for Physical Therapy in 1994 also found no such correlation. The editor of our journal comments that such thinking is "almost heretical in the context of traditional practice." He goes on to say that it seems that we as a profession have simply ignored these studies, perhaps because we cannot stomach the implications.

A simple heuristic, specifically the assumption that muscular activity subsequent to a lower motor neuron lesion (polio) would be the same as that in a healthy system, and that therefore treatment should be the same, has led to a virtual industry of strengthening regimes and machinery designed to influence posture.

This mistaken notion (and I mean there are no studies to support it) is phenomenally entrenched. Its consequences form the bulk of our basic education, and its founders seem unassailable.

Well, I think it's wrong. And I think it's time somebody said something.

This is it.


On muscle performance and posture:

  1. "Relationships Between Lumbar Lordosis, Pelvic Tilt, and Abdominal Muscle Performance" Walker, Rothstein, Finucane and Lamb Physical Therapy Vol. 67 No. 4, April 1987 Pg. 512-515
  2. "Relationship Between Performance of Selected Scapular Muscles and Scapular Abduction in Standing Subjects" DiVeta, Walker and Skibinski Physical Therapy Vol. 70, No. 8 August 1990 Pg. 470- 479 (This includes a commentary by Shirley Sahrmann PhD, PT and an Author's Response)
  3. "Upon These Rocks" editorial by Jules Rothstein PhD, PT Physical Therapy Vol. 70 No. 8, August 1990 Pg. 11-13 "Dynamic Relationships Between Lumbar Lordosis, Pelvic Tilt, and Abdominal Muscle Performance" Levine, David PhD, PT Foundation Focus Fall 1994

On Heuristics:

  1. "Like Goes with Like: The Role of Representativeness in Erroneous and Pseudoscientific Beliefs" Gilovich and Savitsky Skeptical Inquirer Vol. 20 No. 2 1996.
  2. "Judgment Under Uncertainty: Heuristics and Biases" Tversky, A. and Kahneman, D. Science 185 Pg. 1124-1131