Entropy of space–time outcome in a movement speed–accuracy task

Abstract

The experiment reported was set-up to investigate the space–time entropy of movement outcome as a function of a range of spatial (10, 20 and 30cm) and temporal (250–2500ms) criteria in a discrete aiming task. The variability and information entropy of the movement spatial and temporal errors considered separately increased and decreased on the respective dimension as a function of an increment of movement velocity. However, the joint space–time entropy was lowest when the relative contribution of spatial and temporal task criteria was comparable (i.e., mid-range of space–time constraints), and it increased with a greater trade-off between spatial or temporal task demands, revealing a U-shaped function across space–time task criteria. The traditional speed–accuracy functions of spatial error and temporal error considered independently mapped to this joint space–time U-shaped entropy function. The trade-off in movement tasks with joint space–time criteria is between spatial error and timing error, rather than movement speed and accuracy.