The Context of Use for POS Systems
Cashiers use POS systems in high-pressure, real-life settings. The challenge for operators is that they must very quickly check out customers’ purchases or queues will form and customers will become dissatisfied. Efficiency is more than an aspiration. Most cashiers that we have interviewed describe how genuine anxiety builds up with every new customer waiting in line. After all, the POS app is just a tool they use in human-to-human interactions.
But being quick is not the only requirement. Cashiers must be exact in their operation of the system because all of the data the system generates gets fed into complex accounting routines. Mistakes are not permissible and accounting rules are inflexible. Consequently, correcting a minor mistake may require a big effort and come back to haunt cashiers with little time on their hands.
Design Goals for the POS Context
While speed and accuracy are two objectives that every cashier tries to work toward, the contexts in which POS systems are used can differ significantly—from a small store with little traffic to a gas station that experiences sudden onslaughts of dozens of customers to a large store such as a supermarket, in which checkout points experience a constant flux of customers and cashiers must handle a stream of products that comes to them on a conveyor belt. These varied contexts generate very different specifics around the common tasks cashiers must perform, as well as common mistakes and necessary policies.
Many cashiers must both scan the products and operate the POS system’s user interface. Designers must consider what shortcuts the POS app’s user interface can provide, the user journeys, and the amount of information to display at each step. User interface designers should be mindful of all these factors, including the physical setup at the locations where cashiers will use the system.
One of the most important factors affecting the design of POS systems is the set of policies that are in place within the organization the POS system serves. These policies relate to issues such as whether and how a cashier can reverse a transaction—that is, cancel an item—how to apply discounts, and what currencies to accept. Ultimately, all of these elements impose limitations on a design because, most of the time, they are less than ideal from a UX perspective. They are usually devised for the benefit of the business, not the good of the user.
Clearly, the design parameters for a POS system differ greatly from those of a typical consumer app. Therefore, a few less common design principles are useful in guiding the efforts of designers to deliver great products that reconcile user needs with business needs.