tem never actually presents the option of choosing debit instead of credit.

This is not the place to completely redesign the point-of-sale interaction, but we can point out what is missing from the current system and how some basic principles of interaction design can improve it. First and foremost, the system needs to present an accurate picture of which account one’s money is being taken from. “Debit or credit?” should present a choice of accounts, not authorization method. If the industry needs to support multiple authorization methods, it should educate the customer at the point of sale about those choices: the screen should prompt us to “enter PIN or sign below to authorize.” If PIN authorizations are less secure but transfer funds immediately, and signature authorizations carry more protections but take a day or more, the system should present that information in close proximity to the buttons on the screen. If the account the user selects has insufficient funds for the transaction, the system should present that information and present the option of continuing anyway (if the bank permits it), and should indicate how much will be charged for an insufficient-funds overdraft. These modifications improve the visibility of the system, as Norman defined this term: by making the correct controls visible and by making them convey the correct information [ 2]. They enhance the feedback of the system by informing the user of what actions have been taken and what the consequences of further actions will be. By improving the visibility and

feedback of the interaction, they help users build a conceptual model of the entire process that will help them understand when things go wrong, such as when funds are taken from the wrong account, or an unexpected overdraft occurs. Most important, this more robust conceptual model will serve to make future electronic financial transactions more comprehensible.

Some retailers have done a better job than others with their point-of-sale payment systems. Some, for instance, allow the customer to select credit or debit after swiping their card, instead of defaulting to a PIN screen. The Giant Eagle grocery store in my area does this. And to its credit, it replaced the point-of-sale devices as I wrote this essay, and the new system works exactly the same way. My local Lowes, on the other hand, changed from a system that offered the credit-or-debit choice to one that assumed debit/ PIN by default and required the credit customer to press cancel to proceed. Others have eliminated the requirement to authorize payment entirely (and thus to choose an authorization method), typically for transactions below a certain amount. (Panera Bread is an example of a national company that does this.) We can hope that the less desirable interactions soon will be replaced by better ones; indeed, in some areas this transition to understandable interactions is occurring quite rapidly. But this is just another part of the problem: Implementations that are temporary or contingent, that change overnight without warning, make it more difficult for people to become

habituated to the interaction and to build strong mental models to help them understand what is happening in a typical transaction.

It’s Still Too Hard
to Make a Telephone Call

The common cordless home telephone presents another case study in how inattention to the concepts of feedback, visibility, and mental and conceptual models can confound users. A standard analog telephone is already “on” when you lift the handset: The perfectly pitched dial tone provides feedback that the system is ready to receive one or more numbers as input, and a slightly differentiated series of tones provides additional feedback as one enters the numbers. Modern cordless telephones, however, are not “on” in the same way when you pick them up: There is no dial tone. Theoretically, this should not be a problem, as users can begin dialing immediately, just as they would with an older phone, and then “send” the number in some way. But they do not have the audio feedback of the dial tone that the older sets used to indicate that the system was ready to receive a number. The silence of the handset contradicts the user’s mental model of the way a telephone operates, which is carried over from the analog telephone experience.

Most new users in this situation look in vain for an “ON” button and might be encouraged by finding an “OFF” button prominently featured near the top of the button pad. Alas, the corresponding button is usually “TALK,” not “ON.” “TALK” just is not the correct label for these

September + October 2008