The Introspection chapter of You are Not so Smart tells of a study where researchers asked people to rate five types of jam. They five jams the picked had already been rated by Consumer Reports as the 1st, 11th, 24th, 32nd, and 44th in terms of quality.
The asked the first group to provide a list of their preferences by rank without explaining why they ranked each one where they ranked them.
They requested an explanation for the rankings from the second group.
The group just gave a gut reaction came close to matching the rankings given by Consumer Reports. The group that was asked to rationalize their choice ended up being all over the map without any correlation to the ranking from Consumer Reports.
The appropriately-named study (“Thinking too much”) shows why it is dangerous to put too much trust in the power of reason to help us make decisions.
The very act of explaining why we make a choice will cause our decisions to degrade in quality.
Of course, this doesn’t mean that having a reason for our choices is a bad thing. People in the study were measured against those with experience in judging food quality, after all, so it is possible to be rationale about our decisions and still make good ones.
And it doesn’t mean we shouldn’t trust the ability of untrained professionals. The people in the first group came to the same conclusion as the professional food testers.
Instead, I would suggest that this study tells us that the act of making rational, well-reasoned decisions is harder than we think.
Just because someone is able to explain their reasoning for their decision doesn’t mean that decision is any better than someone who is just going with their gut.
(Of course, the chapter just before the one on introspection was about normalcy bias and how it causes many people to not to act to save their own lives in emergency situations, so this shows us that just going with your gut doesn’t always work, either.)