This flight of steps runs up the outside of a Modernist house in Switzerland. What is striking here is the precise construction of relationships. The gaps between steps allow crisp lines of light to fall on the darkly shadowed wall, reinforcing the subtlety of the dialogue between granite and the concrete, which has been bush-hammers to expose the stone aggregates.
...There is something hypnotic about stair climbing, and as often as I find myself thinking I ought to be at the fourth floor when I am only at the third, I think I've only gotten to three when I'm actually arriving at four.
...To my eyes (and legs) the straight run is more elegant and enjoyable to ascend.
...The narrowing is both functional and artistic, acknowledging that a stair is likely to be used by a smaller number of people as it rises and forcing the perspective narrowing of the long view upward.
...The symbolic weight of stairs is embodied in both their form and their magnitude.
For two and a half months I did not see a stairway in America. They are something that has been buried...hidden behind a door that you are not supposed to open.
Perceptual: "They couldn't figure out what to do next", "they couldn't find the feature", "they didn't know they could click that button..." etc.
Domain-specific: "We need a way to jump back here because in their workflow this happens..."
In general, usability testing only catches type 1 perceptual problems. Because in those tests you take people out of the real world and assign them tasks. Usability testing doesn't catch domain-specific problems because they only come up in real life use.