The shortest path from thought to action

"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."

"What emerged came to be called "Fitts' Law," which describes the relationship between the distance to a target and the size of that target, predicting how long it takes for a person to move and select it. The law states that the time to acquire a target increases with greater distance and decreases with larger size. In short, the closer and bigger a button is, the faster and easier it is to click."

"This deceptively simple relationship became one of the cornerstones of human-computer interaction (HCI). Early graphical user interfaces, pioneered at Xerox PARC and refined by Apple, were designed around Fitts's insight. Menus anchored to screen edges, large icons for frequently used commands, and cursor acceleration algorithms all exist to minimize "movement cost." Even today, every pixel and millisecond in a mouse-based interface carries the legacy of Fitts's original experiments with pointing and tapping."

Paul Fitts measured pointing and selection with levers, styluses, and lighted targets to quantify how quickly people move to targets of different sizes and distances. Fitts' Law predicts that target acquisition time increases with distance and decreases with size, so closer and larger controls are faster to select. Early graphical interfaces used this insight to place menus at screen edges, enlarge frequent icons, and tune cursor acceleration to reduce movement cost. The rise of touch transformed the pointer into the hand, making acquisition dependent on thumb reach, finger size, and hand posture. Touch introduced occlusion and imprecision, prompting mobile heuristics like minimum touch target sizes.

Read at Medium