In recent years there has been steadily increasing interest in motor behavior and a growing awareness that a person not only has to know what to do in a particular situation, but also how to do it. Another reason is that the simple tasks studied constitute building blocks of more complex tasks.

Assisted by: J. Annett, W.D.A. Beggs, C.H.M. Brunia, S.A.V.M. Haagh, P.A. Hancock, C.I. Howarth, B.J. Leikind, K.M. Newell, D.A. Rosenbaum, J.G.M. Scheirs, R.A. Schmidt, D. Sherwood, H.N. Zelaznik