It is more than 'paper prototypes' -- you actually need to know how the system should work, from the users' point of view. Ben Cchneiderman (http://www.cs.umd.

It is more than 'paper prototypes' -- you actually need to know how the system should work, from the users' point of view. Ben Cchneiderman (http://www.cs.umd.edu/~ben/ http://www.cs.umd.edu/~ben/) took this a step further in 1987: design the documentation first: Shneiderman, B. (1987), Designing the User Interface: Strategies for Effective Human-Computer Interaction. Reading, Mass.: Addison-Wesley. I referenced the technique in my thesis, and proposed it for aircraft autoflight systems! http://dspace.mit.edu/bitstream/1721.1/37310/1/ICAT-2000-3.pdf http://dspace.mit.edu/bitstream/1721.1/37310/1/ICAT-2000-3.p...