My MIL, (whom I care for), has been doing this for many years so I don't know if it's part of dementia or just her personality, but I'd like to know if anyone else has experienced it.
After hearing someone state a fact, she will state the same fact and look for credit for it, pretending it's the first time it was said. For example, I said, 'Caravaggio painted that,' and seconds later she said, 'Didn't Caravaggio paint that?'. My mother said, 'Shakespeare died aged 52.' and she, having only caught the last words immediately said, 'I saw on the news someone died aged 52.'. My niece said, 'London has a new mayor.' She immediately said, 'Did you know London has a new mayor?' This is constant, everywhere and with everyone.
It's as if she doesn't want anyone else to get the credit, or she is desperate to show she already knew this fact and therefore she is just as clever. It is so blatantly obvious it baffles people, but mention to her someone just said this and her stock reply is, 'Oh did he/she? I didn't hear him/her.' Her smugness when she does this is infuriating. My husband and I just look at each other and laugh, but frustrated strangers sometimes argue with her, 'He/she just said that!', they'll say and become annoyed and then contemptuous when she insists she didn't hear.
What is going on here? Dementia? Or a vanity so overpowering it overrides the brain's ability to rationalise the obvious outcome of such ridiculous behaviour?