In the January 29 issue of the New Yorker, there's an article that should interest anyone trying to teach critical thinking and argumentation. The article is about physician Pat Croskerry's efforts to make sense of why doctors make errors in diagnosis. It's an interesting read, in part because the errors doctors make are so similar to the errors in reasoning that the rest of us, without medical degrees, make all the time. Croskerry believes that many errors in diagnosis happen as the result of errors in thinking that are easily identified and often preventable.
It turns out that looking at doctors can tell us a lot about how we make decisions. Doctors are called on to make diagnoses all the time, and often under very stressful conditions. While they carefully examine their patients, they are basically searching through their mental files of medical problems, trying to find a "match" between a problem and the symptoms they see. To accomplish this efficiently, doctors often rely on different kinds of shortcuts or rules - called "heuristics." Heuristics are, basically, mini-theories generated by experience. We use them in problem-solving all the time, and they function like assumptions. Teachers are storehouses of heuristics. Johnny squinting at the board and having trouble paying attention? Maybe he needs glasses. Students bored and listless in class on a Friday? Time for a fun activity.
And so on. Doctors use a lot of heuristics. As the author of this article points out, doctors are trained to assume that patients with high fever and sharp pain in the lower right side of the abdomen could be suffering from appendicitis. Better send for an X-ray right away! These shortcuts for effective and efficient diagnosis save lots of lives. But they can also cause problems.
Here are three of the common heuristics that Croskerry's identified:
1. Representativeness. This happens when your thinking is overly influenced by what is usually true. Doctors will sometimes look at a set of symptoms and say that they're usually typical of condition X, because when they see those symptoms, patients usually have condition X. This is useful, because it allows doctors (and teachers) to shortcut a whole in-depth examination of each individual patient. But it can cause them (and us) to overlook rare or unusual conditions that don't fit expectations.
2. Availability. We use the availability heuristic when we make a decision about something based on what other examples readily come to mind. Things that are familiar to you are more likely to influence your decisions than things that may be less familiar. Doctors who have recently seen a lot of cases of infection Y are more likely to diagnose infection Y, even if a patient has condition Z. What's immediately available to you in your mind and memory are just more present, tangible, and influential than more distant experiences.
3. Affective Errors. This is the tendency to make decisions based on what we wish were true, rather than on what is actually true. Doctors may relate to a particular patient so much that they fail to perform a crucial examination (as in the example in this article), or they may believe that a positive outcome is inevitable, so they fail to forestall the negative.
The point of this article is that doctors, even though they are highly trained (or perhaps because they are highly trained - an argument for another post), are prone to make errors in thinking just like the rest of us. What teacher can say that she hasn't used all three of these heuristics, often within minutes of each other? Who among us isn't guilty of wishful thinking, hasty generalization, and cherry-picking the evidence?
The idea that physicians have the same reasoning problems as the 6th graders we work with does give me hope, in a strange kind of way - it makes me think that there's nothing particularly wrong with the way our students think, that they're just humans, and what humans do is make mistakes while trying not to. If critical thinking instruction is important in middle school, it's just as important in medical school.
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