Yes, my brain takes some strange twists sometimes. I wish I remembered how that one came about though. It seemed relevant while walking through the cold drizzle 4 hours ago.
Also during that walk, while musing about perceptions, I realized something: Rainy days make New York streets much more crowded. Which seems odd, when you think about it...umbrellas don't actually take up any more footprint space than the person would take up otherwise...
Then it came to me. Sharing umbrella space with a stranger, even for the brief instant it would take to pass them, simply is Not Done. So people end up walking around the phantom umbrella extensions that go to the ground. Very strange. Another perception issue.
Hopefully I'll remember, eventually, what originally set me off on that track, and post it here.