Ok, so this is what happens.
I'm in the changing room on campus, about to head out to my weekly tennis game with Alison, Denise and Clara. I hear two women come in, and identify them from their voices as Denise and Alison. Two women come around the corner and I greet Denise cheerily and smile politely at the unknown woman. 'Oh!' I think, 'Denise has brought someone new to play with'. And then of course I realise it is Alison.
There are some reasons for this misrecognition, however. Before her chemotherapy, Alison used to have gorgeous long, shiny, straight dark red hair. After her hair fell out, she wore a wig that looked exactly like her hair, but for tennis she wore a little cap over her slowly re-growing hair. So I knew it had grown out curly, though no longer shiny dark red in colour. But she had, as she explained, 'come out' as a cancer patient, and was now wearing her curls clipped and coloured a beautiful pearly blonde, and so I did not recognise her, even though (a) I was expecting to see her; (b) I had heard her voice; and (c) I knew she had short curly hair. To cover my embarassment, I found myself explaining the concept of face-blindness. It was only a second or two of misrecognition, but it was obvious that I was greeting one woman as a friend and the other as a stranger. Awkward, especially as the attention should have been on Alison's new look, not my mild cognitive impairment.
Alison also told me one of her students complimented her on her hair, and said, 'Did you have that done for cancer?' Alison hadn't been particularly public about her illness, but thinking she was going to have to face lots of these queries, said, 'yes'. But then it became clear that the student thought Alison had cut or coloured her hair in support of cancer research.
And so we all go on, half-understanding each other, half-recognising each other, and only half thinking about other people.