Consider User Context

"Context" is a broad concept, and one that can play a broad role in usable Point of Sale design. On one side is the context or environment in which employees are using the system—the sum of their experiences, into which the POS is supposed to fit. On the other side, we talk of "context" as pertaining to the experience the user has when using the POS itself. It's this second concept of context I'd like to focus on.

User goals change at many points through the use of the POS. But many Point of Sale designs seem to forget that as user goals change, the set of options needed will change as well. Instead, very many Point of Sale systems I've reviewed aim to maximize the number of options available on the screen—even if those options don't make sense given the user's current goals or context.

By way of example, I recently worked with a client whose existing system tried to support all primary user goals on a single base screen. By trying to be all things at all points, designers had necessarily made the buttons small and had provided no space in between them. This led to slowdowns and accuracy issues as employees would inadvertently "fat finger" the button next to the one they were targeting.

Field studies with this client revealed that a very strong separation along the lines of primary goals would help solve several issues, including the problems created by inattention to user context. Correspondingly, my design mirrored the way the typical employee already thought about things, creating a very clear delineation in the UI between the processes of ordering, tendering, and manager functions. This provided the foundation for additional, "gentler" segmentations of the interface at higher levels—but at each level, presenting only those options which the user was likely to need. Options that were unlikely but still possible were still available, of course, but they were relegated to a sub-process.

Here's something to remember: When trying to find an appropriate balance, don't forget about hardware limitations. Presenting only those options that make sense given the current goals typically means that you're increasing the number of times the screen must refresh in the course of a transaction. If the hardware is old and/or slow, it's possible that the side effects might be undesirable if you take the concept of context too far.

One more thing: Every situation is different, and research is critical to designing a system that works optimally for the target client and target user. POS designs that truly make a difference will be based on a solid understanding of (a) the way users think, (b) the environment in which they work, and (c) how these might change over time.