Fitts' law in the discrete vs cyclical paradigm

Research on Fitts' law has focused on discrete movement and persistently ignored the continuous, cyclical case while adopting an exclusive information-processing approach to the neglect of the energetic dimension of movement. According to current computational accounts of Fitts' law, the slope of the speed-accuracy trade-off should be steeper in the cyclical task and discrete performance should surpass cyclical performance throughout the range of possible task difficulties. Data are reported that corroborate the former, but not the latter prediction. Discrete-cyclical performance equality (trade-offs intersection) was actually observed at a medium level of difficulty. This outcome, along with kinematic data which show a strong correlation between movement harmonicity and performance in the cyclical task calls for a hybrid approach to Fitts' law combining information-processing and energy-saving considerations.