- Peter J Beek: Faculty of Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands. p_j_beek@fbw.vu.nl
F. Mechsner's (2004) Imaginative experiments underscored the importance of perceptual-cognitive factors in motor control. However, his account of motor planning is in need of precise operational definitions of its key concepts; the importance of neuromuscular constraints and coordinative stability is not acknowledged in his view on motor execution; and his account of motor learning is challenged by both empirical and anecdotal observations.