Fitts’ Law
Ian Scott MacKenzie · 2017
This chapter examines Fitts' law beginning with its introduction in 1954 and extending to contemporary use of the law in human-computer interaction. Fitts' original experiments are reviewed and follow-on modifications to the law are explained. Particular emphasis is placed on the adjustment for accuracy and in the calculation of throughput as a human performance measure that embeds the speed-accuracy tradeoff. The benefits of standardization are extolled; the emergence of ISO9241-9 in 1999 is shown to bring consistency to research using Fitts' law to study computer input devices and techniques. An example user study with touch-based target selection on a smart phone is detailed. Throughput overall was 6.85 bits/s, demonstrating a considerable performance advantage for touch-based target selection compared to mouse-based target selection.