Bathtub Confirmation Bias

July 17 2023
By: Shawn M. Galloway

Again, it doesn't drain. With only about six hours of sleep after almost a full day of travel the day before, groggy, I awoke to prepare for the day in a hotel I had stayed in about two months prior. Early in my previous stay, I notified the front desk about the clogged drain in my bathtub. So when showering and the tub began to fill up again quickly, I ascertained the entire hotel must have a plumbing problem. After returning to the hotel from a client engagement, I checked the tub to see if the maintenance task had been completed and noticed something different. The bathtub drain stopper was in an open position.

Reflecting on the showering experience that morning, I realized I never reached down to open the drain. The maintenance person had the easy task of unclogging my bathtub by opening the drain stopper. In my defense, I was tired and not thinking clearly that morning, but confirmation bias got the best of me.

All humans have a self-deceiving, unintended tendency to process information against our beliefs. We look for information, behaviors and experiences that prove our beliefs. My previous experience of a "real" clogged bathtub compared to my second encounter of a tub not draining confirmed it must be the equipment, certainly not a user error, prompting me to quickly accept the situation knowing the solution was to notify the hotel staff again.

We are all affected by this bias in our personal and professional lives. The easiest way to overcome this bias is to recognize or call out the belief you are comparing the experience or information against and look for evidence that you might be wrong. Similar to overcoming an addiction, the first step is to acknowledge there might be a problem, and the problem might very well be that you are wrong.

"Data has an annoying way of conforming itself to support whatever point of view we want it to support." — Clayton M. Christensen

"In social science, in contrast to natural science, it seems that by the time one goes in search of empirical evidence, a favored theory has already been chosen, and evidence is being gathered not in order to test it but in order to confirm it." — Lee McIntyre

"I think it's outrageous if a historian has a 'leading thought' because it means they will select their material according to their thesis." — Antony Beevor