FITTS'S LAW: WHY THE EASY BUTTON WINS

Summary from the TLDR Design newsletter

Fitts's Law, developed from 1954 cockpit-control research, holds that reaching a target gets faster as it grows larger and slower as it sits farther away. Screen edges and corners act as "magic pixels" that are effectively infinite in size on desktop, while touchscreens replace that trick with a thumb-reachable zone. The same principle for making desired actions easy to click can be inverted into dark patterns, like oversized subscribe buttons next to tiny cancel links.