In Wizard-of-Oz prototyping, test persons interact with a supposed autonomous system, which is, however, completely or partially controlled by human actors. The system reactions are generated by the test leader, the wizard, and reported back to the test persons via a user interface. The aim of Wizard-of-Oz Prototyping is to create a realistic interaction between the test person and the autonomous system. In a successful Wizard-of-Oz experiment, the Wizard is not detected until the experiment is completed.
An example of a Wizard-of-Oz prototype is a speech-based interface that in reality does not interact with users by means of speech recognition and output, but is controlled by humans. The words of the user are secretly recorded and passed to the hidden wizard in the background, which initiates a system reaction appropriate to the dialogue.
Wizard-of-Oz Prototyping is used for the generation and analysis of requirements as well as for the evaluation of the usability of systems within the iterative design process. The complexity of Wizard-of-Oz prototypes can be chosen arbitrarily, tests are usually low-cost and agile and the context of the investigation can be extended as required.
