UI Guidelines vs. Usability Testing
Summary: This paper defines UI guidelines and describes the problems inherent in only following guidelines, as well as the danger in being too focused on consistency in your design. It also discusses how usability testing should be used to find out if your product meets the needs of your users and allows them to do their jobs effectively. (4 printed pages)
During the development of software, the main source of recommendations for designers and developers are user interface guidelines. The first and second parts of this paper describe what UI guidelines are, and the problems inherent in only following guidelines, as well as the danger in being too focused on consistency in your design, especially if poor usability is the result. The final section of the paper describes how usability testing should be what you use to find out if your product meets the needs of your users and allows them to do their jobs effectively.
UI guidelines are collections of recommendations that designers and developers follow when creating the user interface for applications. Guidelines can include:
- General design principles derived through research. These principles can include the expression of a fundamental design philosophy, assumptions about human behavior, a design methodology, and concepts embodied in the interface.
- Standards. Most, if not all, major software platforms have published guidelines for user interface design. One example is the Microsoft® Windows® User Experience, which is subtitled the Official Guidelines for User Interface Developers and Designers.
- Local rules or style guide. Many individual companies and organizations have their own set of documented UI rules or styles for interface design that developers in that company use. This is common in large companies especially, where a suite of applications is created internally.
As an application designer, following UI guidelines might help ensure that the product you give your users allows them to apply skills they’ve already learned to common tasks and learn new tasks more easily. However, you cannot rely solely on guidelines to ensure the usability of your product. UI guidelines are often too general. On the one hand, to be guidelines they must be somewhat general. Yet it’s that very generality that makes them difficult to apply. When you are trying to make specific decisions within the context of your product, a general set of guidelines might not give you enough information for you to make a decision. An example is when you’re trying to decide between method A and method B of presenting information in a dialog box.
On the other hand, guidelines can be too specific. For example, a guideline might specify having no more than seven items on a menu. However, adding additional menus might be more confusing to users than having more than seven choices on any one menu. Additionally, guidelines may conflict with one another. For example, one guideline might specify having no more than seven items on a menu, and another might specify keeping similar items grouped together on menus. Which guideline takes precedence? How would you know?
Nevertheless, when designing an application, visual consistency can be helpful. Consider the consistency you find in Microsoft Word and Microsoft Excel. The user interfaces in these software products are very similar in the basic elements such as menus, toolbars, and placement of buttons in dialog boxes—the surface-level interface. In addition, they are consistent in how they handle many common tasks: formatting text, saving files, and so on. Consistency in these and other elements can make it easier for users to transfer skills when learning different applications. Specific UI guidelines help maintain consistency across different products, but consistency by itself is not the ultimate goal.
Moreover, consistency in itself doesn’t ensure usability. It is a mistake to think that consistency in the surface properties of the interface will lead to good design.
These problems really boil down to context: You need to be able to design the user interface for your specific users, goals, and tasks. Guidelines may be a reasonable starting point, but they are only a starting point. The value in UI consistency lies in effective learning, by making it easy to transfer knowledge from another product. However, sometimes ease of learning can get in the way of ease of use.
You must test your product with users to make sure that your initial design decisions are the best for your users and the work for which they are using your product.
Usability testing is the gold standard by which you can determine if the design of an application meets the needs of its intended users and allows them to work productively. Only by gathering empirical data can you find out how well the user interface for a product fits your users’ needs and expectations. There are two scenarios for usability testing:
- If you are a software product vendor, testing real users of your product means you are evaluating for design. Based on how you have designed the application, can users complete the tasks they need to do? Testing real users doing real tasks can also point out if the UI guidelines you are following are working within the context of your product, and when consistency helps or hinders the users’ ability to do their work.
- If you are a software product purchaser, you can do usability testing to evaluate a product for purchase. For example, your company might consider buying a product for their twenty thousand employees. Before the company spends its money, it wants to make sure that the product in question will really help employees do their jobs better. Usability testing can also be useful to see if the proposed application follows published UI style guidelines (internal or external). It’s best to use UI guidelines as an auxiliary, rather than primary, source of information for making purchase decisions.
Articles and Books
- Grudin, Jonathan. "The Case Against User Interface Consistency." Communications of the ACM, October 1989.
- Microsoft Windows User Experience, Official Guidelines for User Interface Developers and Designers. Redmond, WA: Microsoft Press, 1999. (USBN: 0735605661)
- ACM Special Interest Group on Computer-Human Interaction (SIGCHI): The largest organization of UI practitioners.
- British HCI Group: A specialist group of the British Computer Society. See the consultancy listing for contract resources.
- Human Factors and Ergonomics Society.
- Usability Professionals Association: See their consultant directory for contract resources.