A shiny floor may not be wet but it could look that way to someone with dementia. A black mat isn’t a hole in the ground either. And shadows of lattice through a window can look like steps. Mono coloured features are hard to distinguish too. These design details can easily be overcome with some extra thought about perception at the early design stage, or adapted in existing homes and buildings. The Guardian has an excellent article about these issues. It discusses how virtual reality software can bring more awareness to designers about these issues as well as the concepts of universal design.
Editor’s note: taking photos of places and seeing them in two dimensions instead of three really highlights the perception differences.