My cat does not know me when we meet a block away from home, and I gather from his expression that I’m not supposed to know him, either.
~ Guy Davenport, Geography of the Imagination
Even humans have a hard time recognizing what they don’t expect to see. When I worked at a bookshop in Seattle there was a homeless man named Mark who came in almost every night. We spent hours talking together but if I saw him on the street and called his name he’d flash a look of unrecollecting horror at me and run away. Later that same evening he’d step into the shop as amiable as ever without any memory of our earlier encounter.