As any student can tell you, sometimes it takes a lot of work and effort to commit information to memory. When you're studying for a big exam, it might take hours of practice in order to remember what you studied. However, some other events, details, and experiences enter our memory with little or no effort. For example, on the way to class, you might hear an annoying pop song on the radio. Days later, you find yourself still humming that same tune.
