“IN A NUTSHELL, the dull have delusions of adequacy.” “The correlations between the actual IQ measure and the self rating are pretty pathetic at very roughly .20 which suggests general inability to self-assess intellectual ability. Figure 2 shows what the problem is: Dull people over-rate their intelligence. This is interesting, and begins to explain a few things. Dunning Kruger were on to this, but it is nice to see it confirmed for intelligence self-estimation. Brighter people somewhat under-estimate their intelligence, but to a much lesser extent.”

The abstract of the article in question, “Intelligence, gender [sic], and assessment method affect the accuracy of self-estimated intelligence,” can be found here.