Don't Count Button Presses

When designing a Point of Sale system, it's easy to count the number of times the user must touch the screen to accomplish a particular goal. For instance, the process of tendering an order with a credit card requires the user to interact with the computer (e.g., through touching) a countable number of times.

Working to reduce the number of button presses is certainly a worthy goal. The problem comes when designers or well-meaning company representatives use that count as a measure of speed. And things go from bad to worse when button press counts—and the desire to minimize them—becomes one of the primary drivers of the design.

When designers start letting button press counts drive the design, it invariably results in a host of undesirable side effects, many of which actually slow things down. Here are a few side effects I've observed::

  • Too many buttons on the screen, making it harder to learn and harder to find what you're looking for.
  • Buttons and other controls that are too small (and too close together), making the user have to slow down to avoid touching a nearby button.
  • An inflexible design that requires shifting of on-screen elements when company offerings change.

It's critical to remember that speed of service is driven by many, many factors. I did some keypress analysis for one fast-food company and discovered that the number of screen touches accounted for less than 10% of the variance in order times. That means that over 90% of what made an order faster or slower came from factors other than the number of keypresses. It's attention to these factors that will do the most to increase speed of service.