FITTS LAW IN THE DISCRETE VS CYCLICAL PARADIGM

Research on Fitts' law has focused on discrete movement and persistent ly ignored the continuous, cyclical case while adopting an exclusive i nformation-processing approach to the neglect of the energetic dimensi on of movement. According to current computational accounts of Fitts' law, the slope of the speed-accuracy trade-off should be steeper in th e cyclical task and discrete performance should surpass cyclical perfo rmance throughout the range of possible task difficulties. Data are re ported that corroborate the former, but not the latter prediction. Dis crete-cyclical performance equality (trade-offs intersection) was actu ally observed at a medium level of difficulty. This outcome, along wit h kinematic data which show a strong correlation between movement harm onicity and performance in the cyclical task calls for a hybrid approa ch to Fitts' law combining information-processing and energy-saving co nsiderations.