From 1989 to 1992, Harrison served as head of development for Mindscape International, and prior to that as a consultant game designer and graphic artist in the UK. Since joining Sony in 1992, he has held executive management positions in Europe and North America–where he served as Vice President, 3rd Party Relations and Research and Development for Sony Computer Entertainment America from 1996 to 2000. He has been a core member of the teams that successfully launched all of the PlayStation family of hardware formats and innovative software that have helped expand the market for computer entertainment worldwide.