Persona-based design was central to Cooper's work for Sony's (http://www.sony.com) new Passport system for in-flight entertainment. The system is designed to fit into the backs of airplane seats, and provide a variety of movie, audio, and computer entertainment to airline passengers (see Figure 1). Cooper Interaction Design (CID) was tapped to design the system software interfaces, and employed their "goal-centered design" to create a usable and effective system. To do so, CID created the fictional Odyssey Airlines, along with two groups of "personas" for the front-end and back-end components of the application. Four typical passengers were created by Cooper's staff as the target audience for the project. Each passenger was given a name, age, hometown, and occupation. Also, the passenger's attitude toward computers, in-flight entertainment, and patience were modeled into the personas.

Figure 1 Passport to in-flight entertainment. In designing the Sony Passport entertainment system for airplanes, Cooper Interaction Design took great pains to decrease the complexity of the interface to accommodate the spectrum of potential users. Note the disc underneath the display panel: using this disc to navigate through the options simplifies the interface while minimizing the thumping on the back of a passenger's head by an overzealous user.

"You need to get inside your audience's head and understand what their needs and wants are," explained Wayne Greenwood, CID's principal interaction designer and the lead designer on the Passport projects. "Their goals may not be rational, but you need to be sympathetic and understanding of them." Greenwood and his team analyzed the makeup of their personas to determine who their design target would be.

"We come in and role-play this person and that person. If you try to make Ethan Scott (the nine-year old passenger) happy, you make others unhappy," says Alan Cooper. "Soon we found that Clevis McCloud was our common denominator."

Now that Clevis was identified as the primary design persona, each decision in the design process had to survive Clevis's "scrutiny."

"Clevis has no patience for complicated systems, but it doesn't mean that he's less intelligent than our technophile, Chuck Burgermeister. He just isn't a gizmo freak," explains Cooper.

The need to keep the system simple is evident in the design prototype shown in Figure 1 (all the system images accompanying this article are prototypes-the system is still being readied for deployment in airliners). The large disc underneath the display scrolls horizontally, minimizing the amount of touching required to manipulate the system, and providing a straightforward interface. You use the scrolling disc to reach a desired item, and then use a touchscreen to get more information and place an order.

While a touchscreen-only system may seem like the ideal interface solution, CID's design process revealed a notable drawback to such a system. "You don't want someone pounding on your seat back when you're on a trans-Atlantic flight," explains Cooper.