Kattel64
Interesting question.
Mum sings all the words to songs she knows too and can often tell you who sings them, but ask her the name of any item like cup, table or plate and she has no idea. Her speech is mostly a string of unconnected words.
She has no idea who she or anyone else is most of the time, but say "cold heart "and she immediately adds "warm hands."
I have no idea why either, she is not alone in this as several fellow residents react correctly to various words and phrases when there is little coherent speech or understanding the rest of the time.
Kathleen