I'm gearing up for a trip to the doctor for my father, with my sister , in a
couple of weeks, and I'm having a hard time putting into words concisely one
of my father's language quirks.

Basically, he will occasionally say a sentence that just doesn't seem to
have any 'bearings' - something like, 'Were they open?' when we weren't
talking about anyplace being open or closed.  If I dig, usually takes
several promptings to get the basis for the comment, then it makes perfect
sense --perhaps we had spoken hours or days earlier about someplace I was
going and I didn't think they were open, and returned to thinking about it.
It's apparent that he thinks I am part of a conversation that in reality is
an internal dialogue of his own.

He does this constantly with things on TV - he assumes I'm watching,
sometimes even if I'm not in the room, and makes a comment about something
on a program or ad and it takes me a minute or two to work out what he's
talking about.

He does this in making jokes with strangers, too - he will make some remark
to a waitress or grocery store clerk that *I* recognize as a joke, because I
know him and his sense of humor , but to someone not familiar with his
mindset,  would just seem like a non sequitur.  I was driving him somewhere
today, in the new extended-cab pickup truck; Dad has been noticing them
constantly now, and we were parked next to another truck with the owner
standing next to it, and my father said to him, as a joke, as we walked
past, 'My extended cab is bigger than yours!' (the other man didn't realize
Dad was talking to him).

It's basically a matter of not recognizing that other people won't
necessarily understand the context of his comments.  He does this far more
than just forgetting words for things.

Any concise way to explain that long, drawn-out description of his behavior?

Thanks

--
Robert