User-Centred Requirements Handbook |
This method allows designers to create a video-based simulation of interface functionality using simple materials and equipment. Interface elements are created using paper, pens, acetates etc. For example a start state for the interface is recorded using a standard camcorder. The movements of a mouse pointer over menus may then be simulated by stopping and starting the camcorder as interfaces elements are moved, taken away and added. Users do not directly interact with the prototype although they can view and comment on the completed video-based simulation.
Application areas
There is wide application potential, particularly suited for simulating interface functionality. However, it must be possible to simulate the interface elements with basic materials. The method is relevant in the early stages of the design cycle to demonstrate design options and concepts.
Benefits
• Usability problems can be detected at a very early stage in the design process (before a commitment to code has been made). Provides a dynamic simulation of interface elements that can be viewed and commented on by both design teams and intended users. Minimal resources and materials are required to convey product feel. The technique can be utilised by those with little or no human factors expertise.
Limitations
• Staff familiar with the functionality of the intended system are required to create the video prototype. The method does not actually capture a user interacting with the prototype. Because of the use of simple materials, video prototypes do not support the evaluation of fine design detail.
What you need
As with paper prototyping only simple materials are required to create the elements of the prototype to be committed to video-tape. These include paper, acetate, pens and adhesives. A video camera is also required to capture and replay a simulation. The method calls for two people, one to manipulate the interface elements and so operate the computer and the other to control the camera. Little video production expertise is required, although it could be time-consuming to create more complex sequences using stop-motion animation.
Process
The general procedure relating to this method is outlined below. The method parallels that described for paper prototyping in several respects, although the emphasis on creating a video-based simulation is a distinct feature, as is the absence of users who directly interact with the prototype.
1. First, allow enough time to create the prototype, design some scenarios of use for demonstration purposes, and produce the video-based simulation. It should be remembered that even brief sequences of stop-start animation can be time consuming.
2. Assemble the necessary materials. Construct the paper prototype, using separate stock for menus, dialogue boxes and any element that moves or changes appearance. A paper-based mouse pointer for instance can be attached to the end of a strip of acetate so that it can be moved without the operators hands appearing on the video recording.
3. The person manipulating the interface elements should practice playing the role of the computer.
4. Ensure recording facilities are available and functioning. Ideally the camera should point directly at the prototype, perhaps by being mounted above a table where the materials are placed.
5. One person should manipulate the elements of the paper prototype while another person controls the video camera. For example a menu selection can be captured by initially filming a shot of the paper desktop and subsequently filming a brief sequence as the mouse pointer is moved on a transparent arm to a menu item. The video camera is then paused while a paper representation of a menu is placed under the camera, filming then continues while the mouse pointer passes down the menu items.
6. Once completed the video-based prototype can be shown to design teams as well as intended users to solicit evaluative feedback. Several video prototypes can be created and shown to an audience in order to explore different design options.
7. Where necessary the prototype can be refined and the above process repeated. The use of video prototypes supports the exploration of design options by providing a dynamic simulation which can be shown to both potential users and colleagues. This can result in recommendations for the refinement of the initial prototype.
Practical guidelines
• Do not produce too much detail in the prototype as this can distract the users or side-track the discussion.
• Presentation packages can be used to simulate sequences of screens quickly and easily.
• If possible show the user on the video, as well as just system interactions.
Further information
Young and Greenlea (1992), Vertelney, L (1989).