title: (In)dependent limbs during discrete bi-manual movements.
abstract: During discrete bi-manual pointing movements the two hands start highly correlated and gradually decorrelate throughout the movement. In this work we studied whether this decorrelation can be postponed by imposing temporal and spatial constraints at the end of the movement. We compared a simple ballistic bi-manual pointing movement with (i) bi-manually grasping a small object between the two stretched index fingers and with (ii) bi-manually pointing with end time synchronisation on a sound pulse. We found that in the two experiments, the initiations were also highly correlated but the correlations at the end were only slightly higher than during the unconstrained pointing movements. In order to comply with the constraints at the end, subjects compensated for the variabilities at the start with a hand-specific adjustment of the movement time. We hypothesise that during discrete bi-manual movements, the two hands are primarily individually controlled.
authors.affiliation: Perceptual Motor Integration Group, Helmholtz Institute, Utrecht University, The Netherlands. e.j.nijhof@phys.uu.nl
authors.forename: E J
authors.initials: EJ
authors.lastname: Nijhof
mesh_terms: D006225:Hand; D006801:Humans; D009068:Movement / Q000502:physiology*; D013037:Spatial Behavior; D013996:Time and Motion Studies