Event: Birthday of epidemiologist Juan Carlos Finlay, 1833
In 1881, epidemiologists -- disease detectives -- were searching for the cause of yellow fever. Conventional wisdom at the time was that it had something to do with unsanitary conditions and unhealthy air.
One doctor, however, had a different hypothesis. He was the Spanish, Cuban epidemiologist named Juan Carlos Finlay, who was born on this day in 1833. Finley noticed a correlation between the presence of the Culex mosquito and yellow fever. It seemed that the warm weather that brought the Culex also inevitably brought yellow fever. However, when the weather cooled and the Culex disappeared, so did yellow fever.
Finlay tested his hypothesis by having mosquitoes first bite patients with yellow fever and then bite healthy patients. The healthy patients, however, failed to get sick. Based on this evidence, Finlay’s hypothesis was disregarded.
One American doctor, however, remembered Finlay’s mosquito hypothesis when yellow fever broke out where he was working in Mississippi. Henry Rose Carter noted a pattern of yellow fever outbreaks aboard ships that arrived at port in the southern United States. Initially, there might be some cases, but then there appeared to be a period of around two weeks before other cases developed. This caused Carter to hypothesize that there might be a short incubation period.
In 1901, Carter was reassigned to Havana, Cuba, as a quarantine officer. There, he was able to persuade his superior, Water Reed, to put his mosquito hypothesis to the test. Two of Reed’s assistants, Jesse Lazear and James Carroll, agreed to use themselves as guinea pigs. They first had mosquitos bite patients with yellow fever. They then waited for twelve days before letting the mosquitoes bite them. Confirming Carter’s hypothesis, both Lazear and Carroll came down with yellow fever, and unfortunately, Lazear’s case was so severe that he died.
The work of all these doctors to discover the cause of yellow fever confirms what the historian Daniel Boorstin about learning: “The greatest obstacle to knowledge is not ignorance; it is the illusion of knowledge.” Lazear’s initial hypothesis seemed crazy; after all, how could such a tiny insect be the cause of the death of so many people? It seemed much more plausible that the cause must be the unhealthy conditions revealed by the stench in the air.
Challenge - Heroes of Epidemiology: Do some research on epidemiologists who have made great contributions to public health. Identify one person, and explain his or her specific contribution.
Sources:
1-Klein, Gary. Seeing What Others Don’t. London: Nicholas Brealey Publishing, 2013.
Subject: Thinking and Memory - The Brain Attic and Ladder of Inference
Event: Sir Arthur Conan Doyle introduces Sherlock Holmes, 1887
On this day in 1887, the detective Sherlock Holmes first appeared in Arthur Conan Doyle’s story “A Study in Scarlet.” The story was published in a paperback magazine called Beeton’s Christmas Annual (1).
Early in the story, Holmes is becoming acquainted with his new roommate, Dr. Watson, who also is the narrator of the story. As the two talk, Holmes presents a metaphor that explains his philosophy towards knowledge: the brain attic:
I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones. (2)
To sum up Holmes' philosophy, we might say simply, “Garbage in, garbage out.” Clearly, his brain attic metaphor challenges us to be conscious and mindful about how and with what we stock our memory.
One essential piece of hardware we might use for this task is called the Ladder of Inference. Many people need a ladder to reach their attics, but this is not a ladder you will find at the hardware store. Like the brain attic, it’s a metaphor.
The Ladder of Inference was created by organization psychologist Chris Argyris. By breaking our light-speed thinking process down into six phases, we can analyze how we infer meaning, draw conclusions, establish beliefs, and take action. By making our thinking process less hurried and random, we’re much more likely to keep our brain attic uncluttered.
Before we look at the six rungs of the ladder of inference, let’s look at a short story that we can use to illustrate how we might use the ladder.
Sale Lost, Lesson Gained
One early morning, a used car salesman named Jerry arrived for duty. Standing outside, he surveyed his inventory, hoping the day would produce some sales. Suddenly, a yellow Vega driven by an elderly woman turned into the car lot and pulled up alongside Jerry. The woman rolled down her window and asked:
“Do you discount here?”
Jerry responded, “Yes, ma’am,” as he tried to conceal his excitement.
The woman frowned and said, “Pappy always said there’s no bargain in discounted goods.” The woman then rolled up her window and proceeded to drive out of the car lot.
As he watched the yellow Vega in the distance, Jerry thought about the brief encounter. Looking for a silver lining, he thought: “Well, I lost my first customer of the day, but at least I gained a point of view.”
We begin our thinking process on the bottom, first rung of the ladder by FILTERING DATA based on the information we take in from our senses. Sherlock Holmes was a master at observation. He knew that only by deliberately and consciously practicing seeing, can we learn to truly observe. No one sees, hears, tastes, smells, or feels everything; we are all limited by our different perceptions of reality. Therefore, instead of seeing all of reality and all facts, we select a part of reality -- the part that seems important to us based on the context of the situation. For example, in our story, many cars were driving by the used car lot, but our narrator focussed primarily on the yellow Vega that pulled into the lot.
Next, we step up to the second rung by INFERRING MEANING based on what data we have selected. This step requires interpretation and educated guesses, and it can be heavily influenced by emotion, associations, and cultural/personal experience. For example, in our story, the narrator inferred that the driver of the Pinto was looking for a “discount” even though she never explicitly said that she was.
The third rung is where we MAKE ASSUMPTIONS. Often these assumptions are unconscious rather than conscious assumptions. This is also the rung where we begin to build a narrative that will explain what we see and hear. Unfortunately, we seldom question that narrative or generate alternative possible explanations. For example, in our story, the narrator assumed that his interpretation of the word “discount” was the same interpretation as the driver of the Pinto.
The fourth rung is where we DRAW CONCLUSIONS. While these conclusions are influenced by our assumptions, they are also influenced by our prior beliefs, which include a whole range of cognitive biases, such as availability bias, confirmation bias, and cognitive dissonance. For example, in our story, the narrator falsely concluded that the driver of the Vega wanted him to answer “Yes” to the question about discounting. Instead of drawing a rational conclusion based on questioning his prior inferences and assumptions, he jumped to a hasty conclusion.
The fifth rung is where we FORM BELIEFS. Based on the context of the situation, we affirm or adjust our beliefs. For example, in our story, the narrator’s conclusion about the elderly woman became a belief that she was looking for a discount. His belief seemingly blinded him to seeing an alternative possibility.
The sixth rung is where we TAKE ACTION, applying our conclusion and beliefs to a seemingly conscious decision. For example, in our story, the narrator took action, answering the woman’s question with the response that his false assumptions, hasty conclusions, and incorrect beliefs had led him to (3).
Of course, it is too simplistic to characterize the complexity of our thinking process as a simple step-by-step process from the bottom to the top of the ladder. Instead, each rung is influenced by the others. Our assumptions, values, and beliefs influence our perception of the world; therefore, they influence how we select and interpret data, and often our beliefs and past actions influence our perceptions. In our story, for example, the driver of the Vega acquired her negative view of discounting from her “Pappy.” Guided by this belief, she is likely to reject discounting as a positive. The narrator, however, seems to make an adjustment to his beliefs at the end of the story. He says he “gained a point of view,” which leads us to think that the next time he encounters a question from a customer, he will be less likely to jump to a hasty conclusion. He might even generate alternative interpretations and question his own assumptions before drawing a conclusion. He might also have learned a lesson about the influence of emotion (“containing my excitement) on clouding clear thinking.
Challenge - Diagram Ladder of Inference: Draw a graphic representation of the ladder of inference, labeling its six rungs. Think of a situation, a story, or an experience you had that involved decision-making. Break down the process of that decision-making using each of the six rungs of the ladder of inference.
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