Tools for Changing the World

I’m not a psychologist. I don’t even play one on TV.

But I’ve become more and more convinced of the role social psychology can play in making the changes we want to make in the world.

In the above two paragraphs, I just applied one half of the findings of a fascinating study published last year: when an argument is put forward by someone who is not expert in the field, it’s more persuasive when its source expresses certainty about his or her opinion.

This isn’t surprising. In general, we’re more strongly persuaded by a confident speaker, just because we assume that confidence is associated with knowledge and a better ability to make judgements. So what?

The fascinating part comes in the other half of the study’s findings: an expert source is more persuasive when he or she expresses uncertainty.

It seems unlikely. Why would we trust people more when they’re not sure about their own opinions?

It all comes down to incongruity. Uma Karmarkar and Zakary Tormala asked their study participants to read a restaurant review then provide their opinions of the restaurant. Some participants read a very confident review with lines like “Having eaten there for dinner, I can confidently give [the restaurant] a rating of 4 stars,” while others read a more tentative review with lines like “Having eaten there only once, I don’t have complete confidence in my opinion, but I suppose I would give [the restaurant] a rating of 4 stars.”

The reviews could also be written by one of two supposed reviewers: a nationally known food critic who was very familiar with this type of restaurant, or a local computer administrator who normally ate fast food. The reviews were mixed up so that each participant could get either review written by either reviewer.

Results clearly showed that the non-expert reviewer was more persuasive (the readers liked the restaurant more) when he was sure of his opinion, while the expert reviewer was more persuasive when he expressed uncertainty.

Other experiments done by these researchers showed that this happens because we’re surprised by the incongruency between a non-expert source and certainty or vice versa. Being startled makes us more interested so that we read more carefully. If (and only if) the arguments being presented are good ones, reading more carefully is more likely to persuade us to the point of view being expressed.

So, keep this in mind next time you present opinions intended to persuade. A surprising degree of confidence – in either direction – might make your readers more interested and thus more likely to read and be persuaded by your arguments.

In fact, I’m absolutely sure of it.