Over at ScienceNOW is an Unconscious relational memory. Explaining what relational memory is, the article has this:

Try this trick at home: Have a friend remove an object from a room you know well–say, a napkin holder from your kitchen–and then see if you can guess what he’s taken away. Even if you don’t know the answer, your eyes will unconsciously fixate on the stretch of countertop next to the toaster where the holder usually sits. Remembering what goes where in your kitchen is called relational memory, and now scientists have shown that your unknowing stare may be a sign that your brain remembers even when you don’t.

The context of the article is about trying to figure out which part of the brain is involved in relational memory (hippocampus and prefrontal cortex). But here is the conclusion I have absolutely no right to make; one of the more useful skills of a tester is relational memory as applied to a screen in an application. Which means, you could run someone through an FMRI and see if they are better suited at a physical brain level to be an above average tester.

One of the many hitches in that theory, other than the obvious ‘I am not a brain scientist’ is

So your hippocampus may have made the connection that the napkin holder is missing, but your PFC must get involved for you to realize it. “The idea is that recollection may be a two-stage process,” Hannula says. “First you have retrieval of the memory, and then you have a conscious appreciation of what’s been retrieved.”

The whole split between unconscious and conscious appreciation is where the niggly details hide.