Behavioral Psychology in Action
July 16, 2015
Dr. Daniel Kahneman and Dr. Phil Rosenzweig would be mighty proud of me this month. I’ve applied some of the lessons from their books to an important event in my life. I hope sharing the details of this event will encourage you to read their books and help you apply the lessons in your life.
Before I tell you about the event, I just wanted to give you a quick background. I’m in the middle of a 5 book series on behavioral psychology with an emphasis on cognitive biases. I’ve learned a lot of lessons from all the books I have read, and constantly do my best to apply each one of them to all aspects of my life.
Here is the event: Last month, a Glaucoma specialist diagnosed me with Glaucoma on my third visit to her.
Here are some facts:
1) My eye pressure was normal on each visit around 10 to 12. The normal range is 8 to 22, so I was always on the good side of normal.
2) My peripheral vision was normal on the first test, but not normal on the last visit. I told the doctor that something was not right with the test. My eyes were unusually tired that day, and I felt the technician didn’t execute the test properly.
3) My other tests were normal for all 3 visits, except she said my optic nerve was slightly large part on the first visit making me a Glaucoma suspect.
4) I’m Chinese, and the statistics for my ethnicity to have Glaucoma is lower than others.
5) My family has no history of Glaucoma, lowering the chances even further.
6) I’m 36 years old today. Glaucoma usually starts at a later age.
7) I have asthma, and the doctor attributed the Glaucoma to my inhaler.
Thanks to my reading and training as an investor, I was quite suspicious of the diagnosis. I decided to get a second opinion from the chair of the USC Eye Institute.
He was so puzzled with my old doctor’s diagnosis. He said “How can a so-called glaucoma expert diagnose you with Glaucoma with an eye pressure of just 10. All your tests are normal, including your optic nerve. You’re not even a Glaucoma suspect!”
Here are the various cognitive biases that my old doctor exhibited:
Bias #1 Ignoring base rates (population statistics) – By not giving greater importance to my ethnicity, family history, and age, she arrived at my diagnosis from giving the greatest importance to my last peripheral vision exam.
Bias #2 Trusting the data blindly – I already told the doctor that my eyes were tired that day and even blurry during the peripheral vision test. I also mentioned that the test itself might not have been setup properly.
Bias #3 Fixated on one data point (Anchoring Bias) – From my limited knowledge of Glaucoma, eye pressure levels are the determinant of Glaucoma. Despite that, my normal levels of eye pressure and data from other tests were overruled by the peripheral vision test. In one sense, being fixated on one data point is like having Glaucoma of the mind (Glaucoma creates tunnel vision).
Bias #4 Confirmation Bias (looking for information after the decision to affirm the decision) – After her diagnosis, I was asking her how I got Glaucoma, despite being a young Chinese with no family history of Glaucoma. I was thinking out loud and mentioned that I had asthma and used an inhaler. She immediately mentioned that it’s the steroids in the inhaler that caused my Glaucoma. Shortly thereafter, this was easily and quickly disproven by my pulmonologist who provided me with actual clinical research.
I can’t say for sure if my old doctor is unethical. I’m not even 100% sure that she indeed suffered from these cognitive biases. To claim certainty would be a symptom of the overconfidence bias. Our memories have a way of distorting the truth, and no one is immune to cognitive biases, not even me. All we can do is to be aware of the types of biases, and reduce our mistakes.
Thank you Dr. Kahneman and Dr. Rosenzweig for helping me save time, money and stress.