Duh...guess I'm not competent to respond here, eh? But that's never stopped me before (Dunning-Kruger strikes again?).
Got to say that I struggle to see the relevance of the "DK effect" to my working life. In any case, on a purely human level, we'd probably never get out of bed in the morning if we had a truly objective understanding of our limited abilities to cope with all the potential pitfalls in the world outside. Humans are feeble apes with tiny teeth, no claws, no fur to protect them, and they can scarcely outrun a
chicken, yet they have taken over the world: maybe DK is just an evolutionary defence mechanism to let us get on with daily life and try new things: "Making fire? I dunno, but how hard can it be, right?"
Even within the familiar and relatively benign IT world, things are complicated. On the one hand, most of us are college grads, above-average intelligence, perhaps accustomed to being very good at some things, and no doubt vulnerable to being a little too pleased with ourselves on occasion. Obviously we are susceptible to over-estimating our abilities or our understanding of complex problems some of the time e.g. the classic developer's tendency to under-estimate how much work is really involved in solving some problems.
On the other hand, I don't know about you, but much of my working life consists of failure, and being reminded of my own limitations. Think about TDD - test, fail, code, test, fail, code, test, pass, re-factor, test, fail, code, test, fail... Hard to remain convinced of your own infallibility when you only see working code for a few moments each working day before it's taken away for delivery or you break it again! And one of the best pieces of advice I've seen for working in this industry is to make sure you always work with people who are smarter than you are, which is obviously going to bring you down to earth with a bump if you start getting inflated ideas of your own skill.
True, we're all human and thus incapable of judging our own competencies objectively. But that applies to everybody else as well: Am I under-performing because of my "incompetence" or that of my managers? Here in the UK - and I suspect in the USA - we tend to blame the individual "incompetent" worker rather than their manager or the wider working environment, but when I worked in Germany, an under-performing worker was usually seen as evidence that their manager was also failing to help them deliver their work properly. Same problem, different perspective. And then you have wider cultural variations in assessing your own or other people's competence, like those raised in the posts above. What do we do if our incompetence includes the inability to judge competence in other people as well?
My own experience is that most people I work with are good at some things, not so good at others, but I've rarely worked with anybody I'd describe as truly "incompetent" (well, one or two maybe...). Hopefully most of my colleagues feel the same way about me. So it's not really a question of "incompetence", but varying levels, measures and interpretations of what constitutes competence in a particular context. And in a complex and dynamic environment like the average IT project, how easy is it really to pick apart an individual person's specific competencies and assess them objectively, beyond the relatively trivial example of some guy who's a bit slow opening files? One reason recruitment is such a nightmare is that people still seem to have very little understanding of how to measure or predict competence in a given role.
If an individual is under-performing in a particular role, there are so many possible reasons for - and potential responses to - this situation that a narrow focus on a concept like the "DK effect" seems kind of inadequate and probably irrelevant. To my mind this is just too complex an issue to try to address in these terms. But what do I know, right?