 In 1981 back at University of Toronto he was appointed Professor of Industrial Engineering, and member of its Institute of Nuclear Engineering since 1984.In 1988 he moved to the United States to the University of Illinois at Urbana–Champaign, where until 1995 he had a joint appointment as Professor at the Departments of Mechanical and Industrial Engineering; the Department of Psychology; and the Institute of Aviation.From 1995 to 1997 he was a Professor at the University of Valenciennes in France, and from 1997 until his retirement in 2001 he was a Professor of Psychology at University of Surrey in the UK.