Omission Bias

Imagine the following scenario.

You are on a walk when you see a runaway trolley car barreling down the railroad tracks. A group of five people are in the path of the trolley, and are unable to move out of the way in time to escape. You see there is a lever close to you that can switch the direction of the trolley onto another set of tracks. However, you notice one man standing on the other tracks that would also be unable to escape if you pulled the lever.

You find yourself in a moral dilemma with two options. You can A) do nothing and have the trolley kill five people or B) pull the lever and kill one person in order to save five. What is the right thing to do?

While neither option is optimal, most people would agree that option B is the most morally sound—fewer people killed, right? However, you might feel like the action of pulling the lever and killing one person would instill more guilt than the inaction resulting in the death of five people. Even though the consequences of choosing option A are worse, our desire to abstain from any harmful actions (and the subsequent blame) can override the more ethical choice. This famous thought experiment, dubbed “the Trolley Problem,” demonstrates the omission bias in action.¹

It’s worth stressing that, in some ways, the omission bias is the very opposite of the action bias. While the former describes our tendency to judge action more harshly than inaction, the latter describes our tendency to prefer action over inaction. However, both biases align in their underlying premise that doing something feels more tangible to us than doing nothing at all—resulting in an exaggerated emotional response.