The Brain Eating Amoeba and The Availability Heuristic

 The availability heuristic is the tendency to guess how often something happens based on how easily we can think of times it has happened before (Tversky & Kahneman, 1973). In Tversky and Kahneman’s (1973) study, participants were asked whether there were more words that start with “r” or words with “r” as the third letter. It is much easier to come up with words that start with “r” (race, rabbit, red) than words that have “r” as the third letter (tired, corn, war). Since participants could think of words that start with “r” most easily, they used the availability heuristic to infer that more words start with “r” than have “r” in the third position (Tversky & Kahneman, 1973). However, there are actually more words with “r” as the third letter (Tversky & Kahneman, 1973). 

 

The vividness effect states that people tend to trust vivid, anecdotal evidence over empirical evidence (Nisbett & Ross, 1980). 

 

One summer, for whatever reason, there was a lot of news stories surrounding a brain-eating amoeba. I remember that it could be found in water and had been lethal to the children who got it up their noses. For that entire summer, when I swam at the pool, I was very scared of the water getting in my nose. I knew it was silly to worry about. However, hearing the constant media coverage about this random, deadly situation made it come to mind easily. This reminds me of the availability heuristic. Thanks to the news stories, I felt worried that I would also catch this amoeba.

 

Reading about the details behind the deaths was heartbreaking and terrifying. From what I recall, most of these children were playing with hose water or in a lake. They would slowly start to show symptoms over the course of the day, and deteriorate quickly, passing away within a few days. These stories were so compelling, and they made me worry, even though I knew how incredibly rare these kinds of deaths are. I was probably more likely to drown or pass away from a car crash on the way to swimming, but I did not worry about either of those. This seemingly irrational fear of the amoeba can be explained by the vividness effect (Nisbett & Ross, 1980). The personal testimonies of the parents who lost their children held more weight in my mind than the statistic of how many people die of the brain-eating amoeba.

 

n = 406

I have acted with honesty and integrity in producing this work and am unaware of anyone that has not. /s/ Ellie Munson

 

Reference List

Nisbett, R. E. & Ross, L. (1980). Human inference: strategies and shortcomings of social judgment. Englewood Cliffs: Prentice-Hall.

 

Tversky, A., & Kahneman, D. (1973). Availability: a heuristic for judging frequency and probability. Cognitive Psychology, 5(2), 207–232. https://doi.org/10.1016/0010-0285(73)90033-9