 He chaired the Fourth International Conference on Cognitive Modeling (ICCM-2001) and co-chaired the Cognitive Science Society Conference in 2002.He is the founding chair of HFES' Human-Performance Modeling Technical Group (HPM-TG).In 2001 he was elected to a 6-year term on the board of governors for the Cognitive Science Society, where he served as chair and member of the executive committee from 2003 to 2006.