50-50 Overconfidence

January 16, 2020

Many studies, such as this one, demonstrate that people are prone to overestimating their abilities in a wide range of contexts. The methodology of this study, in particular, asks people to answer free-response questions and to then rate their confidence from 0% to 100%. There are many divergent causes for overconfidence, but for specifically this prompt (“how confident are you from 0 to 100%?”), I would propose that there is one source of overconfidence that is easy to overlook and which is quite easy to correct for:

We don’t like to be less than 50% confident.

I think this stems from the strong association between “50-50” and “random chance” in colloquial use, or maybe 50% as a threshold for a failing grade. I frequently see people respond to queries such as “Who was the director of Arrival?” with a “I’m not too sure but I think it’s _______” and in the same breath express that they are “about 70% confident”. 70% sounds kind of low, but it’s actually really high - you’re not too sure, but you get this right 7 times out of 10? The truth is, however, I can’t remember a single time someone has given me a percentage less than 50. I recently tried this once, responding to an open-ended query with “I’m about 30% confident”, and I got a laugh.

We’re generally capable of understanding lower levels of confidence (people regularly bet on long-shots with the understanding that it can still be a good bet even if it mostly doesn’t pay off), but for some reason when engaging in casual conversation, you very rarely hear confidence levels below 50% expressed. I would hypothesize that we feel any confidence below 50% is simply not worth expressing (whether it is because it is “worse than chance” or a “failing grade”), which I think causes two distortions:

  1. We feel compelled to assign a confidence level greater than 50% of anything we do choose to express, even though our true confidence may be well below 50%.
  2. We don’t express opinions with perceived confidence levels below 50%, even though opinions with 30% confidence may actually have a lot of informational content.

Try explicitly doing this a few times and see how weird it feels. But once you’ve done it a few times, you’ve often broken through the mental block holding you back, and you can at least avoid overconfidence in this one little way.