Bright or Dull Cows

A basic diagnostic observation in medicine is whether a patient is "bright" or "dull". Through repeated example, students learn to accurately determine if a cow is bright or dull. By the time they become good at it, what was effortful reasoning becomes perception: the cow just *looks* dull.

"Why do you think that cow is dull?" becomes a question as nonsensical as "How do you know you're hungry?" – you just *are*. This is one way in which Tacit Knowledge𓅮 manifests.

This page is an Example.

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Veterinarians like to classify animals along three axes as a high-level overview. These axes are:

* Is the animal **bright** or **dull**? * Is it **alert** or **depressed**? * Is it **responsive** or **unresponsive**?

Veterinary students are trained to accurately answer those questions. That is, for a given cow, say, a veterinarian trained at Illinois will give the same answers as one trained at Ft. Collins .

How is that consistency achieved? The following is the training procedure as described to me by my wife, Dawn, who did such training for many years.

(Note: the description below has minor differences from how things are done nowadays, but I don't think any of them matter for this point.)

background

At the University of Illinois College of Veterinary Medicine, students spend their last year "rotating" through the various clinical services the teaching hospital offers. A rotation is two weeks long. That means that, every other Monday, all the students currently "on clinics" in the Food Animal section would move to some other section (like Anesthesia or Exotic Animal Medicine), and a new batch of somewhere around six to ten new students would arrive.

Those students have arrived to soak up hands-on training. The existing cases "in the ward" are divided up among the new arrivals, and each new patient that randomly arrives is also assigned to a student.

A good deal of the hands-on training is done by two or so interns or residents. These are people who've completed their Doctorate in Veterinary Medicine but are there to gain more experience (both hands-on and academic). They will demonstrate procedures to the students (on actual patients) and watch as the students try their hands at medicine. "You're going to have to push that syringe harder; remember, you're punching through leather.")

There is, at a given time, one or two "clinicians" responsible for all these people. They are faculty members whose job includes spending some fraction of their time on clinics. Dawn was one of those people, and spent 50% or more of her time on clinics.

Clinicians, day to day, do the same sort of demonstrating and watching as residents and interns do. The difference is that clinicians have greater knowledge, experience, and responsibility if something goes wrong.

The setting for all this training is what looks like a large warehouse room: high ceilings, cinder block walls, various bulky machinery like headgates. The picture below shows the ambiance.

A cow in a headgate

training

The ward has a day-to-day routine.

Students arrive first. They look at their cases. For each case, they write up a *SOAP * (Subjective/Objective [Evidence], Analysis, and Plan). As the name implies, the SOAP consists of observations of the patient's state, the student's interpretation of what that means, disease-wise, and the student's plan for what to do that day.

One thing that will be noted down in the SOAP's subjective observations is whether the patient is bright or dull.

The attending clinician (Dawn) will wander onto the ward at some later, leisurely hour (0800, for example) and lead everyone in *morning rounds*. That means that everyone gathers around a stall to hear the student present the case.

For some reason, students tend to err on the side of judging a dull animal to be bright. Say the first student (nowadays most likely a "she") does that. Dawn would correct her, saying (perhaps) "No, that cow's dull. See: she's not Cleaning Her Nose»."

You can imagine the students furiously memorizing a rule: `NOT cow-cleaning-nose => dull`. Then the group moves to the next stall.

Let's say this cow is bright, but her student has marked her as dull in the SOAP. So:

**Dawn:** No, this cow is bright. **Student:** But she's not cleaning her nose! You just said... **Dawn:** But her ears are perky.

You can imagine students creating a new ruleset:

`NOT cow-cleaning-nose AND NOT ears-perky => dull` `cow-cleaning-nose => bright` `ears-perky => bright`

This process continues with other animals and during other rotations. Eventually, the students get good enough at evaluating bright vs. dull. What's interesting is that, by then, *they've lost the rules*. What was once effortful and algorithmic is now perceptual and automatic. They can see things you and I do not.

my reflections and conclusions

* I think it likely that this ability to perceive dullness is built on something innate. I bet most parents know the experience of looking at a child and thinking "She's getting sick." In my recollection, it's something about the eyes. I suppose that innate ability is repurposed in veterinarians. However, Dawn points out that students have trouble identifying dull cows until they've seen enough healthy (that is, bright) cows, which argues (I think) against my claim.

* One might believe that the students have accumulated a good suite of rules and simply apply them unconsciously. That's what "losing the rules" means – losing awareness of the rules, not the rules themselves. I find that unlikely. Perception vs. Rules»

* I don't imagine that Dawn, when challenged about why a cow is bright, accesses a rule like `perky-ears => bright`. Rather, her brain is scrambling to *invent* an answer, latches onto something that seems salient, and presents that as the reason. But it's an *output* of the decision mechanism, not a part of it.

* I further suspect that `perky-ears => bright` is not so much an explanation as a way to get the "why? why? why?" portion of the student's brain to shut up while some other brain mechanism does the actual learning. That is, the lesson of "Look at her ears. They're perky" is more about making the ears *salient* for perception than it is about building mental categories of ear-types.