Goal
To test requirements and functionality that have not yet been implemented.
What
An experimenter-in-the-loop prototyping technique in a laboratory setting, simulating the behaviour of a theoretical intelligent computer application.
Where
in a controlled environment (for instance a laboratory)
Who
researcher, participant
How
1. Select an idea/concept that will be tested. Create the necessary images, videos, animations and elements to do the test.
2. Recruit participants for the test and organize a location make sure the prototype works. Assign a person as wizard.
3. The wizard hides from view and observes the users actions while making the system react to those actions by triggering the different responses the system should give at that moment in the interaction.
4. Take notes of what works and what does not work while doing the test.
5. Ask participants about their impression of the system and the design. Take notes.
Pros
inexpensive
rapid iterations
early feedback
flexible
Cons
not polished
not real
mixed signals
needs skilled Wizard
Example
https://medium.com/@tiffanylan/a6-netflix-wizard-of-oz-prototyping-d33f933a59a7