12 September 2012


Although I've only played poker once in the past three years, I entered a (free) campus Texas Hold'em poker tournament and won handily. It was shocking. My competitors were devoted poker fans who spoke in poker lingo and followed the competitive poker scene. I, on other hand, was so rusty that I had to ask players to remind me of the order of poker hands. As of writing, I still don't recall if a straight is worth more than a flush. And yet, everything worked. I accurately predicted when to fold, succeeded every time I bluffed, and subtly pressured my opponents into making unwise decisions that I ultimately collected on.

My performance differed from how I fared the few times I had ever played poker, and I wonder if my victory can be attiributed to my transformation into a medical student. Medicine and poker involve managing uncertainty, and most elements of my poker strategy involve skills that I have been honing in medical school.
Anchoring: One of the most common pitfalls in making a diagnosis is that we tend to anchor ourselves too strongly to our initial hunches, even in the face of data to the contrary. It's not just physicians who anchor.

For example, you might ask someone: "How many calories are in an apple?"

You might ask a second person: "How many calories are in an apple? 250? 300?"

The second person will tend to give a higher number than the first. An apple actually has about 100 calories. But by suggesting caloric values of 250 and 300, you have subconsciously anchored them to values near those numbers.
Fast-food chains and stores like Walmart use this trick all of the time. The Subway chain prominently advertises how certain subs on its menu are low in fat. But many of their other subs are actually quite high in fat. By advertising that some of their subs are low-fat, they anchor people to the unwarranted belief that Subway subs generally are low in fat. The effect of Subway's advertising is explored in the wonderful book "Mindless Eating", which I previously reviewed.

Doctors must make sure not to follow their initial hunch too doggedly. While playing poker, I was cognizant of how I mustn't get too attached to my hand, even if I've already bet a substantial amount on it. Several times I resisted the urge to keep betting and folded.

Probability and Bayesian inference: In an intriguing case mentioned in a New England Journal of Medicine case report, a neurologist examined a patient who had been diagnosed with multiple sclerosis. Upon questioning, the patient mentioned that both of his brothers had been diagnosed with multiple sclerosis (MS) as well. The neurologist immediately doubted that the disease was MS, because MS is not a very heritable disease. The neurologist knew that if one's sibling has multiple sclerosis, one's odds of having it are only 1 in 25. For all three brothers to have MS was virtually impossible. Sure enough, the neurologist found that what the brothers had was not MS, but instead a rare (autosomal dominant) genetic disease called CADASIL. Probability led to the correct diagnosis.

In poker, if I am one of eight players at the table, I know that in each round there is a 1/8 chance that I have been dealt that round's best hand. This knowledge makes me fold often.
During each round, I ask myself: probabilistically, how strong are my cards relative to the others'? If someone had been dealt a better hand than me, what is the likelihood that they have folded by now? If there were still a person in this round who has better cards than me, what is the likelihood that I could make them fold? Is the way that a particular person is acting consistent with their having a better hand than me?

These same types of conditional probability questions are what underpin Bayesian inference, a branch of statistics that impacts decision-making. The best diagnosticians use Bayesian inference, consciously or unconsciously, to arrive at the correct diagnoses.

Reading people and interacting with people: Interacting with patients in clinic is helping me with reading people generally. When I ask a patient if they smoke tobacco and they hesitate, I know that no matter what they say afterwards, they smoke tobacco. I'm learning how to make a patient feel more calm, which means that, by extension, I'm learning how I could make them feel bothered.

In poker, I frustrated one of my opponents by intentionally placing a needlessly high bet against her early in a round. I correctly predicted that she wasn't confident enough in her cards to call my bet, and she angrily folded. Her reaction suggested to me that she would want retribution, and that the next time I placed a large bet she would call. Sure enough, when I placed another large bet against her, she called and lost on a weak hand. A few hands later, she went "all-in" against me to try to get me to fold. I suspected that her hand was probably weaker than mine, and I called. She lost and had to give me all of her chips. Her frustration in the face of mounting pressure got the better of her.
I've mentioned some of the ways that becoming a physician seems to be changing me, and not always for better. At the same time, though, medical school is maturing and strengthening some parts of my personality and my thinking. Strange that it was a poker tournament that reminded me of that.