User-based evaluation of unimplemented technology where, generally unknown to the user, a human or team is simulating some or all the responses of the system.
The technique has often been used to explore design and usability with speech systems, natural language applications, command languages, imaging systems, and pervasive computing applications.
The originator, J.F. Kelley explains: "The term Wizard of Oz (originally Oz Paradigm) has come into common usage in the fields of Experimental Psychology, Human Factors, Ergonomics and Usability Engineering to describe a testing or iterative design methodology wherein an experimenter (the "Wizard"), in a laboratory setting, simulates the behavior of a theoretical intelligent computer application (often by going into another room and intercepting all communications between participant and system). Sometimes this is done with the participant's a-priori knowledge and sometimes it is a low-level deceit employed to manage the participant's expectations and encourage natural behaviors (though always, I would hope, with appropriate disclosure during the debriefing part of the experiments)."