Information Cascades and Medicine
Information cascades are fascinating because they don’t necessarily sway individuals into good behavior or bad behavior, they just build on decisions made by a finite few. This is illustrated in how witnessing someone jaywalk can sway a cascade to follow them if a few others are in a rush but can equally enhance caution to stay back and wait if the initial reactions are of disapproval. Even more interesting is that this phenomenon doesn’t only live in the realm of ordinary people putting aside their private opinions for small matters, but applies to experts making major decisions too!
John Tierney discusses a particular example where one confident doctor swayed colleagues across the US to attribute heart disease to a high fat diet. Time and expertise is limited, so even medical experts depend on cues from others to make decisions and guide their own practice. This claim became hard to break from when large organizations like the American Cancer Society and the National Institutes of Health agreed with it. This transformed information cascade to what the article calls a reputation cascade where suggesting that fat doesn’t correlate to heart disease is labeled as controversial and a penalty to your reputation.
But, just as with other information cascades, this belief is relatively fragile. Through the decades, many influential doctors have conducted their own studies which reveal that, without exception, there is no correlation between a high-fat diet and obesity or heart disease. Furthermore, societal encouragement for a low-fat diet could be pushing people to consume more carbs which could be the culprit, but this too could be opening a new information cascade not based on hard evidence. Shifting away from this information cascade is not only hard due to how long it has been marketed as factual, but that there is some intuition (private signals) that low fat should be healthy. Breaking the information cascade and the private signals that individuals hold is a major task that doesn’t happen quickly.
Ultimately, it is understandable to rely on outside expertise and well-developed information cascades to make decisions, but as this shows, when it comes to vital matters such as health, it is important to inspect with “eyes completely open”.
Source: https://www.nytimes.com/2007/10/09/science/09tier.html