1. W.J.R. Bossers, MSc, Center for Human Movement Sciences, University of Groningen and University Medical Center Groningen, PO Box 196, 9700 AD, Groningen, the Netherlands.
2. L.H.V. van der Woude, PhD, Center for Human Movement Sciences, University of Groningen and University Medical Center Groningen.
3. F. Boersma, PhD, Center for Human Movement Sciences, University of Groningen and University Medical Center Groningen.
4. E.J.A. Scherder, PhD, Center for Human Movement Sciences, University of Groningen and University Medical Center Groningen, and Faculty of Neuropsychology, VU University, Amsterdam, the Netherlands.
5. M.J.G. van Heuvelen, PhD, Center for Human Movement Sciences, University of Groningen and University Medical Center Groningen.