The term "interactive" seems to have been coined during the first wave of Internet marketing ventures, a decade or so ago. The objective then, reasonably enough, was to encourage the visitor to a website not simply to read it, but to do something -- ideally, something that would lead to making a purchase.
Vending machines, and many other familiar pieces of equipment, are interactive. Unlike a refrigerator or a letterbox, a vending machine invites the user to do something, and the machine does something satisfying in return. It does not just sit there. This is as true of the simplest mechanical bulk vender as it is of a touchscreen-equipped robotic retailer of high-end merchandise.
This is worth keeping in mind when considering proposals to upgrade the vending machine's user interface to something livelier, something more in tune with contemporary enthusiasms.
Vending presents some novel challenges to interface designers, and it has done so for a long time. On the one hand, imaginative observers have recognized the entertainment component of the vending experience. Machines can be fun to watch in action, as demonstrated most dramatically by the early Snapple glassfront machines by ECC ("Watch the bottle drop!") Anything offered to the patron beyond that momentary pleasure may be problematic.
A machine that's fun to interact with will not be the operator's first choice for a large location in which a great many people visit the vending area at the same time. It isn't the best choice if lines tend to form at the machine. Someone fully engaged in an engrossing experience with the interface will delay, and probably annoy, everyone else. For that reason, the entertainment dimension may be more generally appealing as one of several operator-selectable options.
We think any definition of an interactive user interface has to start with the presentation of the offer: something desirable with which the prospect will wish to interact. There are, and always have been, essential elements to the vending machine user interface that engage patrons before they make a purchase, and even before they have decided whether they want to buy something. These long have been recognized, but still are too often overlooked.
For example, the appearance of the machine should invite the passersby to stop and interact. If it is poorly maintained and it looks as though it hasn't been serviced for months, the patron who does not need something badly probably will prefer to wait to buy it somewhere else.
A less tangible attribute is the clientele's confidence in the machine or machines, regardless of what kind they are or what they sell. When the population of an account comes to believe that the machines don't work reliably, this perception will discourage use and degrade sales. Alert operators therefore always have put a premium on getting off to a good start in a new location.
Of equal importance is sustaining that high level of service, and periodically reminding the account and the clientele that the machines are being taken care of. A well-thought-out and professionally executed preventive maintenance program is an ancient method of doing this, and it still works as well as ever. Today, remote machine monitoring can take this to an entirely new level, but only if the operator has procedures in place for prompt, effective (and visible) corrective action.
Complex systems are prone to occasional disruption, and vending machines have no greater immunity than automobiles, nuclear reactors or human beings. People are well aware, from their own experience, that machines can malfunction. What interests them is what happens next. Every vending machine should have a label identifying the operating company and displaying a number to call for service. When someone calls that number, good things should start to happen quickly. We have known operators who pride themselves on handling all service calls within half an hour of receiving them, unless some local disaster makes it impossible to reach the location. But there still are too many who do not.
We think discussions of the eagerness of the younger generation to participate in social networks should include some consideration of the possible use of text messaging to report malfunctioning vending machines -- and of the new networking media as a potential means of thanking and reassuring the individual making such a report.
Above all, the vending interface should be comprehensible, even intuitive. More than four decades ago, we used an aging postmix cup machine on a New York City subway platform. The machine was protected by heavy steel mesh, but it was clean and attractive, and a little backlit panel over the payment system displayed the illuminated invitation "Insert coin." We did, and the display told us to make a selection. After we did, the message changed to "Preparing drink; please wait." When the cup was full, the message changed to "Thank You," and then reset.
This all might be done more attractively today, but we don't think it can be done any better.