A third approach, rooted in semiotics, emphasizes the role of architectural objects as signs that prompt spectator behavior (Koenig 1964, 1970) or indicate aspects of themselves, such as function (Eco 1968). In either case, architectural objects are taken to operate as communicative systems (Donougho 1987). A semiotics program was embraced by the late 20th century postmodernist movement in architecture (Venturi, Scott Brown, and Izenour, 1972/1977; Jencks 1977).