The Omission Bias and Penn State

There has been a fair amount written on the social psychology of the Penn State state situation (e.g. David Brooks), and I think it’s interesting that most of the discussion has centered on the bystander effect while glossing over the simple fact that people are biased against action. Sure, it makes us feel better about humanity to say there’s some kind of intense self-deception that keeps ups from acting (and certainly there is to some extent), but in reality placing the blame on self-deception may be too generous. The fact is, people generally don’t have moral issues with inaction.

There are a number of studies that illustrate this “omission bias,” including the trolley problem study I mentioned the other day (in which many subjects prefer to let five people die rather than take a semi-active role in the death of one or two people), and an eye-opening 1990 study by Ilana Ritov and Jonathan Baron on decisions to vaccinate a child.

The present study concerns the role of two biases in hypothetical decisions about vaccinations. One bias is the tendency to favor omissions over commissions, especially when either one might cause harm. We show that some people think that it is worse to vaccinate a child when the vaccination can cause harm than not to vaccinate, even though vaccination reduces the risk of harm overall. The other bias is the tendency to withhold action when missing information about probabilities is salient – such as whether the child is in a risk group susceptible to harm from the vaccine – even though the missing information cannot be obtained.

Obviously this doesn’t explain the decisions of Joe Paterno and the Penn State administrators to not investigate Jerry Sandusky more aggressively. However, when you combine the type of passivity endorsed by omission bias + incomplete information with the king-like status of Paterno at Penn State, you begin to see how students could feel so outraged that he would be fired for “doing nothing.” (I also think a large portion of the protest can be attributed to the fact that college students like congregating in large raucous crowds under unique circumstances regardless of the inspiration for the gathering, but that’s a psychological discussion for another post.)
Ritov, I., & Baron, J. (1990). Reluctance to vaccinate: Omission bias and ambiguity Journal of Behavioral Decision Making, 3 (4), 263-277 DOI: 10.1002/bdm.3960030404

Shallow, C., Iliev, R., & Medin, D. (2011). Trolley problems in context Judgment and Decision Making, 6 (7), 593-601


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