Kruger & Dunning, 1999). Briefly put this effects says: incompetent people do not know how incompetent they are. The reason for this is that in order to be able to know how competent you are at something you need to have knowledge about that competence domain. People who know very little about a topic do not realize how much there is to know about that topic and therefore how much competence they lack. The Dunning-Kruger effect means that people who are not so competent at something are inclined to overestimate their own competence. This phenomenon is sometimes referred to as confident ignorance.
It won't be a surprise that the Dunning-Kruger effect can impede learning and cooperation. Recently, another effect has been discovered which also impedes learning and cooperation. This effect is called equality bias. Mahmoodi et al. (2015) discovered, in a series of experiments, that people, when working together, are inclined to give equal weights to each other's judgments, even when they are not equally accurate. In a perceptual task they first asked pairs of participants to independently come to a judgment and then come to an agreed upon judgment. What was found was that these pairs approximately gave equal weights to each other's judgments, also when there was a clear difference in accuracy of these judgments an even when they received feedback about this difference in accuracy.
Thus, the judgment of the most competent partner is under-appreciated while the judgment of the least competent partner is over-appreciated. They may be related to the Dunning-Kruger effect. When the least competent partners overestimate their competence (in accordance with the Dunning-Kruger effect), they may not think it is fair that their judgement would a smaller weight.
The Dunning-Kruger effect thus creates the ironic situation that less competent people, without them being aware of this, overestimate their own competence. To make things worse, as the equality bias experiments show, more competent partners are inclined to go along with the confident ignorance of less competent partners.