It's getting a sense of some kind of measurement of how it is written in the brain. It's not understanding : brain != you. and not limited to the concept. For example, it doesn't take into account how well you "feel" about the concept. People are not computing machines per se. People are very emotional for one thing and without any research everybody knows that your current mood and state of mind influences a lot. Two people with the same understanding could fire different brain patterns, perhaps.