Mental Time Travel

A normal healthy person is capable of mental time travel, in Endel Tulving’s resonant formulation, “roaming at will over what has happened as readily as over what might happen, independently of physical laws that govern the universe.” This is not a metaphor for ordinary planning or recall. It is a precise psychological claim about a specific faculty: the capacity to detach from the present and project oneself—the experiencing subject, not merely a representation of information—into a past event or a future one, standing inside it as the self who was or will be there. The faculty is served by episodic memory, and the most crucial and counterintuitive discovery in its study is that the past and the future are served by the same underlying system. K.C., the amnesic patient whose case Tulving used to anchor the distinction between semantic and episodic memory, could not recall a single episode