The programs in the list are shown in numeric order, so smaller numbers are higher in the list. Pressing “+” will page the list up, so “+” leads to smaller numbers. Similarly, pressing “–” will page the list down, to larger numbers. This follows the same mental model as scrolling in a computer window, including the one you’re reading in, now.

In contrast, when I’m watching one channel (full-screen, so with the program guide hidden), the same two buttons have the inverse effect. The “+” button increases the number of the channel (which is like moving down in the programs list, not up). This follows the same mental model as a spin control in many computer programs.

Imagine using the one button in succession for the two functions:

first as PG to page through the menu
  and then, after selecting a channel,
as CH to step through the channels.

I see in this an excellent problem for a practicum student or as a class assignment that’s combining user research, design, GUI, and handheld devices. Possible questions:

• What research would confirm that this is, in fact, a problem?
• If you confirm the problem, is it entirely on the hardware side? How many people are affected?
• Is there a business case to fix the problem?
• How could you fix it? What design methods and processes would you use? Why?
• How could you demonstrate that your design fixes the problem? Is there a lower-cost way to validate the design, and, if so, what are the trade-offs?