Information system managers are increasingly adopting interface design standards for end-user applications and client-server organizational systems (e.g., Apple, 1987; Berry, 1988; Microsoft, 1992). The primary motivation for interface design standards is ease of learning and use resulting from consistent user interfaces (Shneiderman, 1987; Mayhew, 1992). Consistent user interfaces across applications are thought to facilitate ease of learning and use because a user can draw on existing

more »

... e when learning any new application (Kieras & Polson, 1985; Bennett, 1986; Polson, 1988). However, multiple applications of a variety of types and from a variety of sources are being integrated on the end user's desktop, making interface consistency difficult if not impossible to achieve (Nielsen, 1989). Despite the acceptance of interface consistency guide-Consistent user interfaces across applications are thought to facilitate ease of learning and use because a user can draw on existing knowledge when learning any new computer application. Although empirical research has confirmed that transfer of learning occurs when procedural rules for multiple applications are consistent, no research has been reported that examines the effects of consistent versus inconsistent conceptual models across applications on the accuracy of the user's mental models of the applications. Applications from a variety of sources available to an end user might conform to interface standards for their "look" and "feel;" however, consistent conceptual models across applications (conceptual consistency) are still not assured. This paper reports the results of a laboratory experiment that tested the effects of conceptual consistency across applications on user knowledge, performance, and satisfaction when two integrated cooperative work applications were learned and used by student participants. No differences in performance or satisfaction were found; however, participants learning the inconsistent inconsistent inconsistent inconsistent inconsistent applications formed more accurate mental models of the applications. Schema theory is used to explain the results, and some implications when users initially learn multiple applications are discussed. lines and standards, very little empirical research has been reported that examines the effects of consistent user interfaces across applications.