That's close but a little diffferent. D-K is about assuming your own competence at something you're ignorant in. I think it's caused by the effect I'm talking about, but the root effect is a little broader in that it applies also to how much you assume there is to be known at all by anyone for some field that you're ignorant in.

I'm with ya, yeah, it's almost there. Hmm. I'm not versed enough in cognitive psychology to even guess at what word parts we might throw together to make a new term.