When psychologist Paul Fitts published his 1954 paper on human motor control, he likely had no idea that his insights would one day guide the design of everything from smartphones to virtual worlds. Fitts conducted his experiments using simple physical apparatuses, such as levers, styluses, and lighted targets, to measure how quickly participants could move and point to targets of varying sizes and distances. These experiments were precursors to the pointing and selection tasks that would later define human–computer interaction.