Summary: Because computers are no longer used exclusively for utilitarian tasks, we should use systematic methods to design products that are not just efficient but also attractive to users.
Traditionally, human-factors specialists have had a rather severe attitude toward human performance with computers: their goal was maximum throughput, often measured in transactions per minute. This attitude was justified when computers were mainly work-related; in some cases it still proves wise. For example, a usability improvement that shaves one second off the time it takes a directory-assistance operator to search a database for a telephone number saves several million dollars per year in the U.S. alone.
This performance-obsessed approach to usability led many early user interface experts to condemn the popular term "user friendly" with the argument that users didn't need "friendly" computers, they needed efficient designs that let them complete their tasks faster. I was as guilty as any of this bias, even as recently as the 1994 edition of my book Usability Engineering .
Not Strictly Business
Today, computers are used for many purposes in which the main goal is to please the user rather than maximize transactions. The dual victories of home computing and the World Wide Web last year have emphasized this lesson. However, even in business it is becoming common to cater to subjective whims and user satisfaction.
Many business applications rely on so-called discretionary use, where employees have alternative and often more expensive ways of achieving the same goal. Although window systems design is still focused on traditional usability, frivolous elements like wallpaper and customized color schemes creep in to provide enhanced pleasure for users-- even though excessive fiddling with customization options is a time sink and often results in reduced readability.
The term "seductive user interface" was coined by Tim Skelly (with Microsoft Research at the time) to describe designs that aim at pleasing and attracting users. Unfortunately, not much is known about how to make software seductive; typical advice these days suggests you try to learn from computer games.
As much as I am in favor of the company buying me games, we need a more systematic approach than trying to absorb wisdom while pulverizing space invaders. But pitfalls abound in attempts to treat pleasure seriously.
In his book, I Sing the Body Electronic , Fred Moody tells the story of a Microsoft product team developing a children's CD-ROM encyclopedia and finding different ways to keep kids interested in software. One example in particular highlights the difficulties in developing for attractiveness. The team conducted a usability study comparing two different ideas for some of the main screens: One set had a nearly polished example with color graphics, the other had preliminary designs in the form of black-and-white artist's sketches. Of course, all the kids preferred the color screens, but this result was worthless with respect to the deeper goal of comparing interface styles.
Although it is rarely possible to completely refine multiple designs before doing comparative studies, you should have approximately equal levels of polish and glitz in the prototypes that you want to compare.
One of the few case studies with a systematic approach to seductive design is that by Kay Hofmeester and colleagues from Philips Corporate Design in the Netherlands (" Sensuality in Product Design ," Proceedings ACM CHI96 Conference , ACM, New York, pp. 428-435).
The Philips team was testing for new pager designs targeted at women 18 to 29 years old. The team asked 12 participants from the target group to bring in objects they found sensual; they then questioned the potential users to elicit specific words to describe product qualities. The group was also asked to rate the importance of the properties they had mentioned. The properties organic, human , and body rated the highest; and were thus selected as target properties for the pager designs.
The team then asked the group to discuss pager properties. The team offered only a general description of a pager's functionality; they did not mention the word "pager" nor show pictures of an existing product. This precaution minimized the risk of preconceptions-- such as "a pager must be square and black."
Figure 1. This pager can be worn as a pendant; when worn beneath a garment, the incoming signals are completely private.
Figure 2. This pager has an organic shape and is covered by fabric. It is filled with gel and coated in silicon; this gives it a heavy feel and enables it to reach body temperature when carried.
Based on the elicited ratings, the designers performed a factor analysis of the desired product properties, ending up with three factors, or dimensions along which the potential users differed. Using their design skills and intuition, the designers chose one of the dimensions as the most promising for spanning the user-preference space and developed two new pager designs. The figures here show the results: Figure 1 shows the pager for users with preferences of "flow, wear on the chest, inwards, secret, and mysterious"; Figure 2 for users with preferences of "heavy, fabric, plush, warmth."
In principle, the team should probably have designed products for all eight combinations of the three dimensions, but practical constraints are obviously a concern. That they needed two radically different products for a relatively targeted user group indicates that we may well need to be much more diverse in our design of seductive user interfaces than we were in designing traditional productivity applications.
Because we are in the very early stage of discovering systematic methodologies for making user interfaces attractive, no hard guidelines are available. We do know that we must attack the problem with more empirical studies involving real users so we can determine what they like rather than design with our own biases in mind.
Experience so far indicates that high-quality graphics are the basis for the seductive experience, but are not enough in themselves. For example, sound effects can enhance the experience of graphics significantly, especially when they follow as a result of user actions (such as a satisfying thud when the user throws something into the trash). Animations that perform infinite loops on the screen seem to be less seductive than animations that are teasingly fleeting. However, it is also important to keep traditional functionality and usability concerns in mind -- being seduced is frustrating if you try something and nothing happens.