I'm very bad at remembering names.
There are few occasions when it's actually necessary to do something right away.
Indeed. How many of us, when the telephone rings, immediately abandon everything and rush to it before the caller can ring off, even though we are not expecting an important call? I know I do and yet, as someone pointed out to me, when it rings, you don't HAVE to answer it.
I only ever answer the telephone when I feel like doing so. In fact, I only ever do anything these days when I feel like it! Perhaps the inadvertent act of 'going blank' to which Michael R refers is simply the result of an overwhelming lack of wish
to do anything at that particular moment.
There are times when we all must feel the need for total silence and privacy of thought, even in circumstances where we are supposed to be interactive with others. Perhaps we are at those times viewed as merely 'uncommunicative', 'unhelpful' or downright 'rude'. But we are all human, and this feeling comes to all of us at various times - whether through stress, tiredness, or whatever other personal circumstances may cause it.
But it is surprising how poorly some recognise it in others, and how quick they are to infer negative motives.