This has started happening more often to me particularly when I'm solving a crossword puzzle. (But I think long-term storage and what we're thinking about at the moment are separate functions in the brain.) --Dan Steve Gray wrote: << Here is a speculation on something nonmathematical. It often happens that we can't recall a word or someone's name but "know that we know" it. Consider the memory space taken up in two cases: 1. We recall the name with no problem. 2. We can't recall it, but it still takes up the same amount of memory, plus the space needed to realize we can't recall it. Brain economy would, I think, prefer the easier situation. So why does it ever happen that we know that we know it but can't recall it? Admittedly a very naive view, but this and other evidence convinces me that storing and retrieving are very different operations.
Sometimes the brain has a mind of its own.