An acoustic metaphor
In this model of lost and ill-found memories, there is imagined to be competition between past and present moments, and that competition is metaphorically audible. That is, the true present and the true past are said to emit sounds, and whichever is louder, that's the one you call THE present. And what you do from that point depends on the persistence of this sound. Until it peters out, or sinks below or is overcome by the volume of a competing sound, your attention is captured, or imprisoned.
To summarize in proverb form: the present isn't the nearest part of the past, it's the loudest part of the past. And to offer up another proverb: the volume draws you there, the reverberation keeps you there.
In my first version of this model, reverb had a somewhat different effect, one hard to rationalize with word recognition, which itself hardly affects or is affected by perception of past and present. In my experience, people with dementia don't lose or scramble semantic memory anyway. They pretty much remember what words mean. It is episodic memory that challenges them. They still have such memories - and in both these models it is postulated that they never lose them. In the case of an episode's details, however, the revisitation of these may confuse the demented. The revisitation works all too well, and they get stuck in the past.
How this is normally avoided, how the process might begin to be faulty, how faults might be temporarily overcome, and how they might get even worse are what the present model is intended to illustrate.
In this version of the model, the aforementioned "moments" are presented as itineraries of two-day drives - lists of U.S. states, the middle one being where you overnighted - and your memories of them are short narratives. Here's the set of itineraries that's hardcoded into the model.
Also hardcoded into the model is a set of proposed itineraries imagined to issue from the present. When you click the button, you are hearing (well, seeing) one of these, and trying to remember it. In the ideal, "undemented" state, you will. All of these itineraries correspond to trips you did once take. The first version of this model had a few red herrings thrown in, as life itself will, but I decided to leave those out. (You are however given another button to click, one that tosses the idea of a trip you didn't take and won't remember. Just to see what effect if any they have on the process. It may not be much.)In the varying degrees of dementia proposed to be modeled here, all your memories are still available and reviewable. But with metaphorical volume and reverb playing larger (and largely unwelcome) roles, you may not simply glimpse an episode from the past, recognize it as such, then return to the present. These factors may detain you, long enough to CHANGE where you THINK you are in time.