title: Is Fitts' law continuous in discrete aiming?
abstract: The lawful continuous linear relation between movement time and task difficulty (i.e., index of difficulty; ID) in a goal-directed rapid aiming task (Fitts' law) has been recently challenged in reciprocal performance. Specifically, a discontinuity was observed at critical ID and was attributed to a transition between two distinct dynamic regimes that occurs with increasing difficulty. In the present paper, we show that such a discontinuity is also present in discrete aiming when ID is manipulated via target width (experiment 1) but not via target distance (experiment 2). Fitts' law's discontinuity appears, therefore, to be a suitable indicator of the underlying functional adaptations of the neuro-muscular-skeletal system to task properties/requirements, independently of reciprocal or discrete nature of the task. These findings open new perspectives to the study of dynamic regimes involved in discrete aiming and sensori-motor mechanisms underlying the speed-accuracy trade-off.
authors: UMR 7287 Institut des Sciences du Mouvement E.J. Marey, CNRS and Aix-Marseille Université, Marseille, France. rita.sleimen-malkoun@univ-amu.fr
authors: Rita
authors: R
authors: Sleimen-Malkoun
authors: Jean-Jacques
authors: JJ
authors: Temprado
authors: Raoul
authors: R
authors: Huys
authors: Viktor
authors: V
authors: Jirsa
authors: Eric
authors: E
authors: Berton
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D016014:Linear Models; D008959:Models, Neurological; D015233:Models, Statistical; D008962:Models, Theoretical; D009048:Motor Skills; D009068:Movement / Q000502:physiology*; D025341:Principal Component Analysis; D011597:Psychomotor Performance; D012044:Regression Analysis; D013997:Time Factors