Time for an expert: I asked Professor Jürg Nänni, author of the exemplary Visual Perception, a book detailing our best-to-date scientific understanding of the processes involved in visual cognition. “Could rounded rectangles actually take less effort to see?”
Nänni confirmed my theory: “You are absolutely right. A rectangle with sharp edges takes indeed a little bit more cognitive visible effort than for example an ellipse of the same size. Our “fovea-eye” is even faster in recording a circle. Edges involve additional neuronal image tools. The process is therefore slowed down.”
IT’S PROBABLY ONE REASON WHY ALLCAPS is so frikkin’ annoying, too.