Wizard of Oz


The Wizard of Oz technique enables unimplemented technology to be evaluated by using a human to simulate the response of a system.


This technique can be used to test device concepts and techniques and suggested functionality before it is implemented.


The "wizard" sits in a back room, observes the user's actions, and simulates the system's responses in real-time. For input device testing the "wizard" will typically watch live video feeds from cameras trained on the participant's hand(s), and simulate the effects of the observed manipulations. Often users are unaware (until after the experiment) that the system was not real.

The "wizard" has to be able to quickly and accurately discern the user's input, which is easiest for simple for voice input or hand movements. The output must also be sufficiently simple that the "wizard" can simulate or create it in real time.


The Wizard of Oz technique can provide valuable information on which to base future designs. It can:

  • gather information about the nature of the interaction
  • test which input techniques and sensing mechanisms best represent the interaction (so that subsequent effort developing or adapting sensing technologies is appropriately directed)
  • test the interaction of a device before building a functional model
  • find out the kinds of problems people will have with the devices and techniques
  • investigate aspects of the products form such as visual affordance (whether the product shows how it can be used)

More information

Usability testing in user input device design Timothy Griffin

Wizard of Oz MARBLE project

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