I've always struggled with this. I am not good at thinking on the spot. I like to say that my brain "simmers" my thoughts - low and slow. This makes all sorts of things challenging - having adhoc conversations, making good impressions during an interview, etc.
It's nice to hear someone articulate what I've never been able to really put into words.
I discussed this with a psychologist once who said this is an executive function issue. Something related to working memory, if I recall. Fairly common in those with ADHD, but I’d guess not limited to that.
It's nice to hear someone articulate what I've never been able to really put into words.