Comment by foxhop
8 years ago
This is an incredible read, very thought invoking.
I've never replaced stairs but I have learned enough of the "details" by repairing them (or being aware of them) to know it's a really hard to get right.
A single 1/4 inch difference between two steps can feel wrong; a 1/2 inch difference and people will likely stumble or tumble down them on their first approach. Our intuition and pattern recognition impacts how we solve problems. Some call it "muscle memory" but it's not just in our muscles, it's in our unconscious thought.
Like the author explains so well, once we move a detail into our unconscious it becomes part of us, transparent to us, "common sense"; and an unnoticed detail is completely hidden from us.
The details of reality can only be taught through experience, because once understood, they move almost instantly from hidden -> transparent.
A gif of what happens when one step is just slightly too high:
https://imgur.com/hl3YWJD
A favorite "today I learned" of mine is that staircases in medieval castles were constructed with steps of slightly different heights in order to trip invaders. In particular, the last step at the top of a staircase was tall, with the intent of causing a stumble and generating a loud footfall (for those sneaking around) or sending the intruder into the room headfirst (into a ready weapon, in the case of a siege).
Source video: https://www.youtube.com/watch?v=ap-22FjgoE4
This was the perfect strange comedy for my Friday morning, thank you for sharing!
Also interesting how people speed up after tripping.
I had an over weight friend in highschool who could run really fast. He did this by basically by making his top half fall forward which caused his legs to move quickly to keep him from landing on his face.
I think this is a similar phenomenon where the people tripping up the stairs have an imbalance causing their top half to fall forward. As a result the unconsciously speed their bottom half up to catch the top half from falling.