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  • Writer's pictureIslon Woolf MD

The Kruger-Dunning effect - a cognitive error bad for your health

Updated: Jun 7, 2020

If you want to learn why your facebook friends claim to know how to cure cancer, but your Internist does not...

The Case of McArthur Wheeler

Kruger-Dunning effect

After robbing a bank without a mask, McArthur Wheeler was spotted on security cameras and apprehended shortly afterwards by police. When questioned about the lack of a mask, he claimed that he applied lemon juice to his face. Perplexed, the police asked him to explain. "Lemon juice" he explained, "has been used for ages as an invisible ink, and therefore, if rubbed on the face he reasoned, it could help evade being seen on a security camera". This strange but true story inspired two psychologist, David Dunning and Justin Kruger, to learn about incompetence.

Lack of Metacognition

McArthur was certainly too stupid to rob a bank, but he was also too stupid to realize he was too stupid to rob a bank. He lacked metacognition. Metacognition (meaning - "above thinking") is the ability to step outside one’s own mind and watch oneself think. A form of self-reflection to assess one’s own cognitive skills. (It is something encouraged both in Cognitive Behavioral Therapy and most meditation practices.)

The Illusion of Superiority

Another cognitive error linked with McArthur’s behavior is the illusion of superiority; also known as the ‘Lake Wobagon effect’. This illusion is responsible for the fact that 90% of us think we are better drivers than the average person, 90% of us think we are better looking than the average person, and 90% of us think we are smarter than the average person. I certainly have never met a doctor who said, “Compared with other doctors, I am average”.

From an evolutionary perspective why would we have the illusion of superiority? Possibly, thinking we are more skilled than we are could have survival benefits such as dealing with hardship, maintaining self-esteem, or inflating ones self-worth to others in our group.

The Kruger-Dunning Effect

In the modern world, however, an illusion of superiority and lacking metacognitive skills are a bad combination. A kind of evolutionary mismatch. Kruger and Dunning put this all together to write their important paper in 1999. The Kruger-Dunning effect - simply stated - amateurs are surprisingly confident despite being incompetent. They don’t know that they don’t know.

If McArthur had metacognitive skills and humility he would have thought the following thoughts before robbing the bank:

  • Do I have the skills necessary to rob a bank?

  • The people designing the technologies to protect a bank must be very experienced and smart.

  • Do I know enough about these technologies?

  • It can’t be easy to rob a bank otherwise everyone would be robbing banks.

  • What percentage of bank robberies are successful?

  • What methods were used when robberies were successful and what methods were used when not?

  • * If lemon juice makes me invisible to security cameras do I know how to test that hypothesis?

  • * Why has someone not used this lemon juice trick before to rob a bank?

The more you learn the less you know

Most of you are probably very knowledgeable in at least one topic. Think about that topic. How many years did it take for you to become knowledgeable? How do you compare what you know now with what you knew then? Have you noticed progressively more complexity to a seemingly simple idea? Did those years of experience leave you with more questions than answers?

Likely, you noticed that increasing experience leads to a deeper understanding of a topic - and the realization of more complexity. Therefore, when you embark on a new topic do you have the cognitive humility to acknowledge that answers may not be as simple as they initially appear? Can you acknowledge that just because you are bright in one field, it does not make you bright in another? Linus Pauling, the famous physicist and Nobel prize winner, couldn’t. He devoted his life after physics and staked his reputation on the hunch that supplemental Vitamin C is a cure-all. (Sorry to disappoint but... other than causing kidney stones and saving pirates from scurvy it’s pretty much useless.)

Being wrong is the normal state in medicine

In my last email on cognitive dissonance and opposing nutritional claims, I explained the dissonance my sister-in-law experienced when a new diet vilifying plants conflicted with her vegan beliefs. This kind of cognitive dissonance is not new to experts in the field. In my 30 years of learning medicine I have experienced it at least several hundred times. Here is a small incomplete list of some of the ideas that have changed since I entered medical school:

  • Opening stable blocked coronary arteries with angioplasty - not helpful

  • Tonsillectomy to prevent strep - not good

  • Antidepressants for mild to moderate depression - probably not good

  • Cortisone injections for tendinitis - not helpful in many circumstances

  • Knee arthroscopy for meniscal tears - not any better than physical therapy for degenerative meniscal tears

  • Digitalis for heart failure - not good

  • Antioxidants to prevent cancer and heart disease - does not work

  • MSG syndrome - does not exist

  • Chronic fatigue - not explained by hypoglycemia, Epstein-Barr Virus or gluten

  • Stress is the main cause stomach ulcers - not true

  • Stress causes cancer - not true

  • Saturated fat causes heart disease - not true

  • PSA testing helps to significantly reduce prostate cancer death - not true

  • CA-125 and ultrasound screening help reduce ovarian cancer death - absolutely not true

  • Yearly screening chest x-ray - not helpful

  • Hormone replacement in women to prevent heart disease - does not work

  • Antibiotics for bacterial infections - does not work in all circumstances and may affect gut microbiome

The ideas I once thought sacred and immutable were, in fact, wrong. It does not shock me anymore. This is the nature of medicine. The ideas are temporary, acting as a placeholder, until they are proven, disproven, or something else better comes along.

(this is known as the pessimistic meta-induction argument - that is, because science is always proving older science wrong, the newer science is also probably wrong.)

An excellent book covering this topic of medicine being wrong is here.

Knowledge in medicine uncovers increasing complexity

antioxidants hypothesis is dead

When we are wrong in medicine we usually realize that the human body is more complex than we initially thought. The antioxidant hypothesis stands as an excellent example. It was first proposed in 1956 by Denham Harman. Free radicals are constantly produced in your cells as a by-product of metabolism - just being alive and breathing results in the release of free radicals. The free radicals cause damage by binding to cell structures such as DNA. This leads to aging and diseases of aging such as cancer and heart disease. However, free radicals can be neutralized by antioxidants. Fruits and vegetables contain lots of antioxidants and the people who eat them seem very healthy. So far so good... Unfortunately, further study with hundreds

of very large clinical trials testing antioxidant supplements against placebo yielded not a single benefit (accept in the AREDS study of macular degeneration). The antioxidant hypothesis is dead. Billions of dollars and trillions of pills later, where did we go wrong? It turns out that after 3 billion years of evolution, cells have learned to protect themselves from free radicals by producing their own antioxidants. When antioxidants are given in a pill form, the internal production of antioxidants is shut down - net effect is zero. We underestimated the complexity of human physiology.

As we uncover fields like the human genome, the epigenome, the microbiome, and stem cells it does not lead to more answers; rather, it leads to more questions, more complexity, and more reasons to be wrong.

Kruger-Dunning effect in medicine

Lately, we have all noticed the abundance of amateurs, biohackers, bloggers, supplement sellers, Silicon Valley CEO’s, and vegan sister-in-laws making health claims with extreme confidence. Even within medicine, there are doctors that change from one field to another, and start to make big claims. I am not a surgeon and certainly wouldn’t profess to know how to rearrange your cardiac blood vessels; why a Columbia heart surgeon has become the nations expert on weight loss supplements and anti-aging skin creams is beyond me?

The oversight common to all of these over-confident individuals is that they miss the grand scale of ideas in medicine. Usually latching on to a single idea, they fail to see their idea often has a counter-idea claiming the exact opposite. Their idea is but one of hundreds of unproven ideas and one of thousands of already disproven ideas.

Thus, the reason medicine is so prone to the Kruger-Dunning effect is because human physiology is revealing itself to be increasingly more complex, the volume of ideas is growing exponentially, and most of the ideas are wrong; leaving only experienced individuals with the wisdom to avoid falling prey to the latest, greatest, trendy idea. Without an understanding that we are almost always wrong, it’s hard for most entering medicine to appreciate that they, indeed, could be wrong. They don’t know that they don’t know.

Ways to remedy the Kruger-Dunning effect

Learning critical thinking is the best solution to counter the Kruger-Dunning effect. Here is an introduction to critical thinking in medicine if you are interested.

A few quick tips:

  • Have humility when approaching a new field.

  • Seek out opposing arguments.

  • Seek out people with experience and without bias (Don’t treat yourself with diets, supplements, medicines, or experimental injections without asking an unbiased expert.)

  • Learn the history of your idea. Where did people go wrong in the past with similar ideas? Is it possible your are making the same mistakes?

  • Don’t confuse what you want to be true with what is true.

  • Try to verify the credibility of your sources

  • Don’t rob a bank without a mask.

Be like Socrates

Socrates critical thinking medicine

Critical thinking in Western thought began a long time ago with Socrates. In "The Apology of Socrates", Socrates’ friend comes back from the Oracle at Delphi and tells him what the Oracle said, “there is no man wiser than Socrates”. After inquiry into the so-called experts of his day, Socrates realizes that the Oracle was correct. Neither the experts nor Socrates had any remarkable knowledge; however, Socrates possessed one insight they did not, “I know that I know nothing”.

For those of you interested in further exploring the topic of ignorance, see this video by architect and TED conference founder Richard Saul Wurman. He attributes his success to the fact that he embraces his ignorance, “I always strive to be the dumbest person in the room”.

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