 Distinguishing between remembering and mere imagining requires identifying one or more memory markers, where a memory marker is a factor that discriminates between remembering, whether successful or unsuccessful, and mere imagining. The concept of a memory marker is itself importantly ambiguous. On the one hand, memory markers might be understood as factors that the rememberer himself can employ, from the first-person perspective, to discriminate between remembering and imagining. On the other hand, they might be understood as factors to which the theorist of memory can appeal, from a third-person perspective, to discriminate between remembering and imagining.