This book is the final product of a conference organized at the Free Univer sity Amsterdam by some members of the Dutch Human Performance Group and sponsored by the Dutch Psychonomic Society. We first of all thank the Society for financially supporting this publication and the Free University for providing technical support. P.J.G. Keuss A.A.J. Mannaerts and W. Hulstijn members of the organizing commitee and J.A. Michon and W. Molenaar collaborated with the editors in defining the fields dealt with at the conference and in the book and in getting together the team of authors. All the chapters in this volume have been reviewed by a team of external referees who generously spent their time to improve the readability coher ence and scientific standard of the work as a whole: H. Bogers Institute for Experimental Psychology University of Groningen The Netherlands; P. Innocent Leicester Polytechnic UK; G.A.M. Kempen Institute for Cogni tion Research and Information Technology Nijmegen The Netherlands; J. Moraal Institute for Perception RVO/TNO Soesterberg The Netherlands; I.M. van Oorschot Department of Economics Free University Amsterdam The Netherlands; G.R.E. Ouweneel Institute for Experimental Psychology Haren The Netherlands; J.G.W. Raaymakers Institute for Perception RVO/TNO Soesterberg The Netherlands; G. Rohr IBM Science Center Heidelberg FRG; M.J. Tauber Department of Computer Science University of Paderborn FRG; Y. Waern Department of Psychology University of Stockholm Sweden; G. d Ydewalle Department of Psychology University of Leuven Belgium.