Is there a word for this type of involuntary memory?

Sometimes I will be thinking about something, and a completely unrelated memory will pop in to my head. Often it’s a memory from something that happened a long time ago, of something I may not have consciously thought about for a very long time. Importantly, there is no obvious connection between what I was consciously thinking about, and the “involuntary memory” that occurs.

This differs slightly from the wikipedia definition of involuntary memory, which seems to describe some kind of link between the conscious memory and the unconscious memory. Eg, thinking about a certain type of food might trigger an unconscious memory of a time when you were eating that food.

But is there a word for when there is no obvious connection between the conscious and involuntary memories?

Random.

There may, of course, be an unobvious connection. When this kind of thing happens to me, I spend an inordinate amount of curious time trying to figure out what the original line of thought has to do with the other thought or memory that popped up in my head. Most often, in my case (my head), there is. For instance, once upon a time I was racking my brain trying to think of what song and singer it was that was earworming me. It turns out to have been Tom Petty, singing the song “Learning to Fly”. But while I was trying to dredge it up, my mind kept going to a one-off album by most of the characters who had been Emerson Lake & [del]Palmer[/del] but with Cozy Powell on drums replacing Palmer. The earwormy song was most definitely not on that album and that group didn’t have that kind of sound either.

Once I knew the name of the song that had been my earworm, it made more sense: the Emerson Lake and Powell album has a track on it also titled “Learning to Fly”. Different song. Somewhere in the back of my head, the connection was made and was trying to give me clues, which I missed, but it wasn’t really random memory if you see what I mean.