· Percy K. and Vida L. W. Hudson Professor of Computer Science, Columbia University2013–
· Chair of Computer Science, Columbia University2012–2018
· Technology Leader, Human-Computer Interface Research Department, AT&T Labs Research2000–2003
· Division Manager, Human-Computer Interface Research Department, AT&T Labs Research1996–2000
· Division Manager, Human-Computer Interface Research Department, AT&T Bell Laboratories1994–1996
· Member of Technical Staff, Linguistics Research Department, AT&T Bell Laboratories1985–1994
· PhD, Computer and Information Science, University of Pennsylvania1985–
· MSEE, Computer and Information Science, University of Pennsylvania1982–
· Assistant Professor of History, Smith College1977–1982
· PhD, History, University of Michigan1976–
· Instructor in History, Smith College1974–1977
· BA, Eckerd College1968–