title: Testing the role of expansion in the prospective control of locomotion.
abstract: The constant bearing angle (CBA) strategy is a prospective strategy that permits the interception of moving objects. The purpose of the present study is to test this strategy. Participants were asked to walk through a virtual environment and to change, if necessary, their walking speed so as to intercept approaching targets. The targets followed either a rectilinear or a curvilinear trajectory and target size was manipulated both within trials (target size was gradually changed during the trial in order to bias expansion) and between trials (targets of different sizes were used). The curvature manipulation had a large effect on the kinematics of walking, which is in agreement with the CBA strategy. The target size manipulations also affected the kinematics of walking. Although these effects of target size are not predicted by the CBA strategy, quantitative comparisons of observed kinematics and the kinematics predicted by the CBA strategy showed good fits. Furthermore, predictions based on the CBA strategy were deemed superior to predictions based on a required velocity (V (REQ)) model. The role of target size and expansion in the prospective control of walking is discussed.
authors.affiliation: Faculté des Sciences du Sport, Institut des Sciences du Mouvement, Etienne-Jules MAREY, UMR 6233 Université de la Méditerranée and CNRS, 163 Avenue de Luminy, 13009 Marseille, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Bastin
authors.forename: David M
authors.initials: DM
authors.lastname: Jacobs
authors.forename: Antoine H P
authors.initials: AH
authors.lastname: Morice
authors.forename: Cathy
authors.initials: C
authors.lastname: Craig
authors.forename: Gilles
authors.initials: G
authors.lastname: Montagne
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D014584:User-Computer Interface; D016138:Walking / Q000502:physiology*; D055815:Young Adult