Im pretty sure a lot of the trouble spotting contacts is simply because we are looking for a single pixel on a flat image. I had a look at a track replay in 3d at duxford and it made an enormous difference. Could spot contacts so easily as they floated above the background.
I think we need some form of artificial spotting aid. At least in 2d, we are massively handicapped at the moment compared to real life and this just isnt "realistic"