For Physical Therapists: How NOT to think like a turkey

Do you want to avoid thinking like a turkey?

To NOT think like a turkey, first consider HOW turkey's think...

It's the day after Thanksgiving and a newly hatched turkey has arrived.

He has the coop to himself with plenty of room and no competition for food, etc.

Then, some humans arrive at feeding time. They provide food and water.

After that, they turn the lights down low, turn up the bed warmers and play some soft music.

"My," observes the turkey, "these humans must really love me - they must really be my friends!"

The turkey observes this same process for 364 more days.

Each day is an independent observation that seems to confirm the initial observation - that humans are friendly benefactors of turkeys and would never do anything to harm a turkey.

Then comes Thanksgiving Day and the humans arrive at feeding time - only instead of food they carry hatchets and axes.

"I wonder what those are for?" thinks the turkey.

Needless to say, the turkey dies with a very surprised look on his face.

The Outcome is Dinner

Now, what did the turkey do wrong?

How could the turkey have come to a different conclusion about humans presented with the same set of facts?

What could the turkey have done differently to change the outcome?

The Fallacy of Inductive Logic

The turkey committed the fallacy of inductive logic, first described in 1748 by David Hume, a Scottish philosopher, economist and historian.

Hume's contribution to empirical thought is an important cornerstone of the scientific method and to evidence-based medicine.

"Inductive inference is reasoning from the observed behaviour of objects to their behaviour when unobserved...it is a question of how things behave when they go (in Hume's words)...

"beyond the present testimony of the senses, and the records of our memory."

...we tend to believe that things behave in a regular manner; i.e., that patterns in the behaviour of objects will persist into the future..."

Hume's story uses chickens, not turkeys.

I have adapted Hume's story because turkeys resonate with Americans at this time of the year (Thanksgiving/Christmas).

Turkeys, chickens, David Hume and physical therapists are all searching for one universal constant - the TRUTH.

How can we find it?

For the physical therapist, TRUTH is the answer to these questions:

• What treatment will make my patient better?
• How long will the treatment take?
• How much better will my patient get?
• How much will the treatment cost?

In Hume's time the problem of induction was seen as a barrier to finding the truth. In other words, inductive reasoning (thinking like turkeys/chickens) did not seem to be the path to secular enlightenment (ie: the TRUTH).

Today, the foundation of the scientific method is hypothesis formation, usually by inductive reasoning.

The hypothetico-deductive model (thinking like physicians think) uses inductive reasoning to generate the initial hypothesis, and then to test the hypothesis:

1. Experience: What previous treatments have worked?


2. Why did the previous treatments work? What patient characteristics are unique to the responders (note: this example specifically describes Treatment Based Classification, or TBC).


3. Identify the patient characteristics (from the history or physical exam) that best predict which treatments worked (the outcome).


4. Test your theory.

What could the turkey have done different?

Find one human that likes to eat turkey. Then, the turkey could change his behavior to change the outcome (on Thanksgiving Day, run like hell).

In science, we question our assumptions - we test our theories and we learn from our failures. We're skeptics.

In physical therapy, we call this reflection.