P. Langdon is Senior Research Associate at the University of Cambridge, UK, and is also External Examiner for the Kings College London and Guy's Hospital Intercollegiate MSc in Assistive Technology. Dr Langdon holds a PhD in Experimental Psychology from the University of Sheffield, UK. His research interests include the properties and design of Haptic interfaces; the representation and formulation of statistical data on disability; and the integration of software development and empirical methodology. P. John Clarkson is Professor of Engineering Design and Director of the Cambridge Engineering Design Centre at the University of Cambridge, UK. After receiving a PhD in Engineering (Electrical Machines) from the university, he spent seven years as Manager of the Advanced Process Group for PA Consulting Group's Technology Division. His current research interests are in engineering design, particularly the development of design methodologies to address specific design issues. P. Robinson is Professor of Computer Technology and Deputy Head of Department at the University of Cambridge Computer Laboratory in the UK. He is also a Fellow, Praelector and Director of Studies in Computer Science at Gonville & Caius College within the university, where he previously obtained his PhD in Computer Science. His research interests include human-computer interaction and electronic design automation.