This week I had a good opportunity to discuss an interesting cognitive bias with one of my 4th year medical student while we were on renal rounds. The issue came up when I was examining the belly of one of my young patients, who screamed out, “your hands are cold”. One of our nurses was quick to respond, “Cold hands, warm heart”. My student looked at me then remarked that she had only recently ever heard that expression, and since then has been hearing it over and over again. This, of course, lead to a natural discussion of the cognitive bias called the Frequency Illusion, which also is known as “The Baader-Meinhof Phenomenon”. I admit we had to look up the name, as neither of us could remember what it was called. As physicians and scientists, critical thinking and rational thought are vital, and one way I teach this to my students is by discussing cognitive bias and logical fallacies. These emphasize where limitations of the human mind lie, and how to avoid common pitfalls in thinking that we are all prone towards.
The frequency illusion is one we have probably all experienced from time to time. The example above, is a not unusual. My student may have heard that phrase before, but never really registered it, or perhaps really never did hear it before recently. In any case, the true frequency of the phrase is unlikely to have suddenly increased, but only my students perception of the phrase has lead her to believe that only now is she hearing, “cold hands, warm heart” all over the place. Cognitive scientists propose that when the human mind has been given new information, it creates a bias towards that information so that we are more likely to become aware of seeing or hearing that same information again the next time it is presented. This is known as a “Recency Effect”. In reality the information has always been present at the same frequency but until recently it was part of the background noise and not in the forefront of thought.
Another example of the Frequency Illusion is one that I noticed in myself this week. This occurred after a friend of mine posted on Facebook that he and his wife were visiting the Florida Keys for vacation. Since then I have noticed several commercials on TV advertising the Florida Keys for tourism. I had never noticed those commercials before. Now, it is possible that those commercials have only just begun to be broadcast, my friend was influenced by the commercial and decided to go to the Florida Keys, and I only started noticing the commercials because they were never on TV before this week. A more likely explanation is that I have fallen victim to the Frequency Illusion.
And yes, my hands really are cold all the time, and my heart is around 98.6 degrees Fahrenheit – so pretty warm. I guess my nurse was right after all!
Reference articles:
1. “The Baader-Meinhof pheonomonen”, How stuff works.
2. Structure of a logical argument. The Skeptics Guide to the Universe page.
3. “The Clumping Effect” Darwin’s Kidneys blogpost.
4. List of Logical Fallacies. Wikipedia.
darwin's kidneys 