However, evidence of absence is unlikely to be found as the vast majority of researchers tend not to bother publishing papers with negative results. So if an idea seems like it should have been researched already, but no research papers are to be found, it may very well be because the evidence of absence simply hasn't been shared.
I wonder how many papers give a negative result because p was found to be .049 or so. I'm recalling that thread here a while back debating whether the statistical critical value is too high.