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Method

Wizard of Oz

A prototype in which a hidden person, the “wizard,” produces the system's responses by hand while the participant uses it as if it worked on its own.

In Spanish
Mago de Oz
Origin
Kelley (1984) gave it its name; the technique had been used before, for example by Gould, Conti and Hovanyecz (1983)
Output
People's reactions to a simulated system and what the real system needs to do

What it’s for

It lets you check whether an interactive idea, such as an assistant or a service with artificial intelligence, makes sense to people before you program it.

Key elements

  • Make it feel real

    The person experiences it as if the system already worked.

  • A wizard with a script

    Whoever responds rehearses first and follows rules, so the system behaves the same in every session.

  • Tell them at the end

    Afterward, explain who was responding and talk about the experience.

How it’s done

  1. Prepare the tasks, the wizard's script, and a place where the wizard can't be seen.

  2. The person tries it and the wizard responds live.

  3. Adjust the script and test again.

Applications in design

  • When to use it

    To test an assistant, a chat, or any “intelligent” system before building it.

  • Avoid

    Letting the wizard improvise: if the answers change every time, you won't know what failed.

  • Don’t fall for it

    Make sure the wizard isn’t slower than the real system would be: delays give the simulation away.

Connections

Related to

Authors and works

  1. 1984

    J. F. Kelley

    He used it to design a calendar program that understood English sentences: at first he gave every response himself and, as the program grew, he stepped in less and less.

  2. 2018

    Marc Stickdorn, Markus E. Hormess, Adam Lawrence and Jakob Schneider

    They describe it as a cheap way to prototype services, with “wizards” who play people, devices, or the environment.

Sources

Original sources

  • Kelley, J. F. (1984). An iterative design methodology for user-friendly natural language office information applications. ACM Transactions on Office Information Systems, 2(1), 26–41. View source: Kelley, J. F. (1984)
  • Stickdorn, M., Hormess, M. E., Lawrence, A., & Schneider, J. (2018). Wizard of Oz approaches [Method]. This is service design doing. View source: Stickdorn, M., Hormess, M. E., Lawrence, A., & Schneider, J. (2018)
  • Stickdorn, M., Hormess, M. E., Lawrence, A., & Schneider, J. (2018). This is service design doing: Applying service design thinking in the real world. O'Reilly Media.
  • Gould, J. D., Conti, J., & Hovanyecz, T. (1983). Composing letters with a simulated listening typewriter. Communications of the ACM, 26(4), 295–308.

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