Remember how I’d wondered if aphantasia and autobiographical memory deficits could be limiting not just retrospective visualization but prospective visualization as well? Your Brain Is a Time Machine doesn’t directly address that question, but it does directly suggest an answer for amnesiacs.
People with so-called anterograde amnesia generally lose the ability to store new semantic and episodic memories—although they can still learn motor tasks such as learning to ride a bike, and other types of so-called procedural or implicit memories. Previously stored semantic memories (for example, the names of their family members or the capital of France) are largely intact, but some amnesiac patients also have an impoverished ability to recall old episodes of their lives (those that happened before the onset of amnesia).
It is not surprising that someone with amnesia will struggle to describe what he did yesterday—that’s pretty much the definition of amnesia. But do people with amnesia struggle to plan ahead or to describe what they may be doing tomorrow? The answer to this question seems to be yes. Research over the last two decades has progressively emphasized that some amnesiac patients struggle to project themselves into both the past and the future. Once such patient, who was known by the initials K.C., suffered extensive hippocampal damage as a consequence of a motorcycle accident. In addition to losing most of his episodic memories, he had a pronounced deficit in his ability to think about his own future.