Would it be possible to understand the results differently? It looks to me that the data could be explained by the participants moderating their self assessment away from extremes or perhaps towards the population mean which is arguably not an unreasonable thing to do if your knowledge of the population mean is better than your knowledge of your own performance.
And this is why we need error bars on all plots. Looking at these plots there is no way to know whether people guessed uniformly or whether the self assessment is clustered around the mean.
Yeah I agree that's the likely explanation. Nobody wants to admit that they're terrible and nobody wants to boast that they're the best and be proven wrong.
So my suspicion is that the DK effect is not really a symptom of people's inability to accurately self-assess, but they're unwillingness to accurately report that self-assessment.
And I don't think it is unique to self assessment either. It's common knowledge that ratings on a scale out of 10 for pretty much everything are nearly always between 6 and 9.
I don't know how they did the experiment but I bet they'd get different results if the self-assessments were anonymous and accuracy came with a big financial reward.
Anyway that's all irrelevant to the point of the article which I think is correct.
