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Fool’s Plight: The Dunning-Kruger Effect

14/09/2009 Leave a comment

(Total reading time: < 4 minutes)

The Dunning-Kruger effect is a cognitive bias that warps our ability to judge our own competence. To put it very bluntly, stupid people tend to think that they are quite brilliant, because they are too stupid to tell that they are, in fact, stupid.
(Don’t worry, I know it’s a bit more subtle than that.)

The effect is named after Justin Kruger and David Dunning, who discovered it by doing a series of tests, after the completion of which the participants were asked to guess how well they think they did. The participants were also asked to evaluate their general skill in the tested subject. For example, taking part in one of the experiments, you would have first completed a written test of logical reasoning, similar to an IQ-test. You would then have been asked to guess how well you did in this particular test and also asked to evaluate how good you generally are at logical reasoning.

Here is what the results of the study looked like:

Dunning Kruger2

In the graph, the results are sorted by how well the participants actually did in the test, as we can see from the Actual Score plot steadily rising from left to right. A minor effect that can be seen is that practically everyone evaluates their own ability as being slightly better than their test scores indicate. Basically, everyone is saying “I might have made a few mistakes in this test, but generally, I’m pretty good at this”.

By far the more dramatic effect however, is that most participants dramatically misjudge their abilities. For starters, everyone thinks they are better than average (>50), an effect also known as Illusory Superiority. As we can see, the worst performers’ estimation of their own skill is quite similar to the best performers’ estimation. It seems that those who actually are of slightly more than average skill have the most realistic assessment of their own skill. The best performers underestimate themselves, which might be partially due to modesty.

Dunning and Kruger state that the cause of the effect is that incompetence at a certain skill also robs one of the ability to make an accurate judgement concerning that skill. This, coupled with the tendency to protect one’s feeling of self-worth (a tendency every healthy person displays) inevitably leads to the crass overestimation shown in the study.

If you would like to learn more about the studies, I highly recommend this post on Pro-Science. It even includes a link to the original research-paper, which you can download.

Practical Examples

In the opening paragraph, I made the very condescending statement that stupid people are too stupid to recognize their own stupidity.

This is true, but you have to keep in mind that we are all stupid at some things. I know that I’ve experienced the DK effect myself several times. I have often underestimated the difficulty and complexity of a task (and therefore also my expected skill at it), before I knew much about it. Maybe the “I’d be pretty good at that/I bet that’s easy”-effect is a mild version of the Dunning-Kruger effect. Have you encountered any of the following, thinking them yourself or hearing someone make a similar statement?

  • Photography is really easy. It’s not like painting or drawing, where the artist actually has to do something.
  • It must be great to be a novelist, all they have to do for a living is tell stories.
  • I can’t believe how crappy this movie/videogame/comic/website is! Even I could do better than that.
    Of course, once you get into serious photography, try to write a book or make a movie, videogame, comic or website, you’ll encounter a whole new world of complexity and difficulty and as you progress, you become more humble.

Another example of the DK effect is very familiar to me from martial arts training: Many students of martial arts become overconfident after about eight to twelve months of training. With some, but only very little, experience under their belt, they tend to think they are invincible and could take on almost anyone. This is the time when they are also most likely to give tips to others, correct them and otherwise try to help them. After a while, if they keep training, this usually settles and they realize that there is still a lot to learn.

What Can I Learn from This?

The DK effect is certainly very interesting, but is it also useful to know about? First of all, I believe knowledge of the effect can help you avoid falling for it. As described in some of the work done by Dr. K. Anders Ericsson, experience is a pretty good indicator of skill. So instead of asking yourself “How good am I at this?”, ask yourself “How many hours have I put in?”. If the answer is “dozens” or “hundreds”, then it’s unlikely that you are already very skilled. If, however, the answer is “thousands”, then it’s more likely that you can trust your intuitive judgement of your own skill.

To me personally, the Dunning-Kruger effect is one of the reasons I want to dedicate most of this blog to exploring and testing, rather than just expressing opinions.

For an interesting philosophical approach to the DK effect, check out this post on ribbonfarm. To see why my testing and exploring might get me nowhere, see this tidbit on the connections blog. I’m not sure if I want to dedicate a post to the subject mentioned there as well.

Mistaken Expectations, Wrong Predictions

06/09/2009 Leave a comment

How do you decide what restaurant to go to, which movie to see, what pants to wear today? And what about big and important decisions like what career-path to choose, where to settle down and buy a house or whether to have kids or not? To some extent every decision we make is based on predictions. We imagine what an evening at one restaurant would be like versus an evening at a different one and make our desicion based on where we imagine we will have more fun, get better food and other criteria.

Interestingly, there are some systematic mistakes we tend to make when we imagine such future events and this can lead us to making bad decisions. Dan Gilbert is a psychology professor and the author of Stumbling on Happiness, a book that I am currently reading and might have to add to my list of recommended books soon. Watch the video below to see Dan Gilbert talk about how we make decisions and where we go wrong. The video is very much worth seeing, not just for it’s interesting content but also because of Gilbert’s wit and charismatic delivery.

If you enjoyed this and want more, you can watch another TED-talk by Dan Gilbert here (what makes us happy?) or visit his website.