MULTIMEDIA USER INTERFACES
Multimedia user interfaces combine several kinds of media to help people use a computer. These media can include text, graphics, animation, images, voice, music, and touch. Multimedia user interfaces are gaining popularity because they are very effective at keeping the interest of their users, improve the number of information users remember, and can be very cost-effective (Alexander, 1992; Fletcher, 1990; Verano, 1987).
Several reports support the value of multimedia. Bethlehem Steel found that multimedia training courses cut training time by 20% to 40%, improved retention rates 20% to 40%, and allowed employees to take training when it was most convenient (Alexander, 1992). A Department of Defense literature survey (Fletcher, 1990) concluded that, in higher education, interactive videodisc training roughly improved the performance of students in the 50th percentile to about the 75th percentile of performance. Big 5 Sporting Goods reported (Wilder, 1992) that training time for a point-of-sale cashier dropped about 75% to 50%, cashiers made fewer errors at the point of sale, cashiers and sales representatives retained their skills, and the company standardized training. Another study (Verano, 1987) found that the greater the level of interactivity in the course materials, the more students learned. Compared to standard classroom lecture, students who used interactive videodiscs retained 19% more information when tested four weeks after the training period.
Successful multimedia designers build their products with primary emphasis on the user. Multimedia designers determine which human sensory system is most efficient at receiving specific information, then use the media that involves that human sensory system. For example, to teach someone how to fix a part on a jet engine it is probably most efficient for the student to watch someone else fixing the part rather than hearing a lecture on how to fix the part. The human visual system is better at receiving this complex information. So, the designer for this multimedia product should probably use video as the medium of communication.
This heavy emphasis on the user's senses, rather than the media, means that we should probably call these product user interfaces "multisensory" rather than "multimedia.". The human senses that designers use most frequently in their multimedia products are sight, sound, and touch. Multimedia products often stimulate these senses simultaneously. For example, a user can see and hear a video and then touch a graphical button to freeze the video image.
Since so many media are available to the multimedia user interface designer, it is very easy to overwhelm and confuse the users of these products. The following guidelines are based on the way people think and perceive information. These guidelines will help you build multimedia user interfaces that are easy and comfortable for people to learn and use.
Here are some general guidelines.
- Keep the user interface simple -- This is the most important guideline to remember when you design multimedia user interfaces. Don't show off what you can do with multimedia technology. Instead, give the users only what they need to do their tasks. One study (Miller, 1956) suggests that you provide only five to nine choices for the user to select at one time. As Thoreau wrote, "Our life is frittered away by detail. ... Simplify. Simplify.".
- Be consistent -- Use similar objects to perform similar functions throughout your product. That way, what users learn in one place they can use in other places. This quality helps users learn your product quickly and builds their confidence.
- Let the user control the interaction -- Let the user, rather than the computer, control what happens next. Let the user decide where to go, what to see, and when to leave. For example, when watching a video, let the user cancel the video rather than watching the whole thing before being able to move on. That way, if the user saw the video during an earlier interaction, he or she does not have to see it all over again.
- Give immediate, obvious feedback for every user action -- Let the user know that the computer is working and that it received and is responding to the user action. For example, when the user selects a push button, change the button to inverse video, and have the computer emit a short beep and process the action on the push button. This design characteristic will help keep the user interested in using your product.
- Use familiar metaphors -- Take advantage of the user's prior learning by using familiar objects and actions. This characteristic improves learning and increases user comfort. For example, if the user needs to dial a telephone number, provide an image of a telephone with a touch-sensitive keypad. The user recognizes the telephone and knows how to make it work. Other familiar metaphors include televisions, video cassette recorders, and calculators.
- Let the user safely explore your product -- The user should be able to navigate through your product without worrying about breaking or deleting something. If appropriate, don't provide a delete function. If the user needs to delete objects, design your user interface so the user can confirm or cancel a deletion. Let the user undo actions that are not easy to reverse. Let the user go back to the previous screen from the current screen. Make obvious what the user can do next. These design characteristics help make your user interface inviting and comfortable.
