Consider the example of the gas pump interface pictured above. In the past two years many stations have begun to require that users enter their zip code as part of the payment authorization process. I am sure there are sound information security reasons for making this change (although a little bit of googling “zip safe” uncovers international travelers frustrated because they do not have a U.S. zip code to associate with their credit card; and others who find their cards locked out after a few fill-ups until they enter the store and make a purchase with the same card). But what intrigues me is the additional labeling that has apparently become necessary for users who don’t understand the designers’ (SCREAMING) short hand: “KEY ZIP: ZIP CODE.” Did this additional label solve the problem? Did confused users 1) even read the secondary labeling and, if so, 2) interpret the colon as the word “means”? Or did the label raise more questions than it answered, thus necessitating the additional Zip Safe label with a 3-part (three!) instruction on how to enter the zip code?
Designers should always take a step back when additional labeling is required to help users understand an interaction. Each label increases the users’ cognitive load exponentially, and in an environment such as a filling station, where users have other things to monitor such as weather, children in the car, other cars waiting for the pump, etc., it is simply unlikely that additional layers to the interface will solve an interaction problem. A *possible* solution to the Zip Safe dilemma would be for the interface to offer 4-6 possible zip codes, where the user has to identify the correct one. This would at least clear up the confusion over what kind of information is being asked for, and would also allow for an “International Card” option for visitors from other countries. But like any interaction design, this approach would need to be prototyped and field tested to learn whether it really makes life easier for people at the pump.