Universal-Design Principles and Heuristic Guidelines

Heuristic evaluation is a usability inspection technique during which one or more usability experts use established heuristics, design principles, or rules of thumb to review and assess a product user interface during an independent walkthrough, then report issues and share the resulting insights to help design teams enhance the product’s usability and user experience. A heuristic evaluation can provide a thorough assessment of a product or application’s user interface, detect usability issues that might occur during user interactions, identify user experience issues, and quickly and relatively inexpensively provide useful feedback to UX designers that helps them identify ways to resolve issues. However, a heuristic evaluation should not replace usability testing. Instead, use heuristic evaluation in combination with usability testing to obtain the best information about the usability and accessibility of a product or application.

The Seven Principles of Universal Design

At NCSU, Ronald Mace’s working group of architects, product designers, engineers, and environmental-design researchers developed the Principles of Universal Design in 1997. The purpose of UDP is to help designers and consumers understand the characteristics of products and environments. These universal-design principles comprise the following:

1. Equitable use
2. Flexibility in use
3. Simple and intuitive use
4. Perceptible information
5. Tolerance for error
6. Low physical effort
7. Size and space for approach and use

By following these principles, you can design systems for use by everyone, under all conditions. Our modern digital world has expanded the horizons of UX design to encompass multimodal systems that provide more than one input channel to users, enabling them to interact with devices through speech, nonspeech sounds, touch, gestures, and handwriting. Augmented reality (AR) and virtual reality (VR) are new technologies that require an amalgamation of universal-design principles and usability heuristics.

In this article, I’ll focus on how universal-design principles enable UX designers to design for diverse sensory, physical, and cognitive impairments; as well as different age groups and cultural backgrounds. You can apply these principles to physical products and software applications for desktop computers, the Web, and mobile devices.

Mapping UX Design Principles and Usability Heuristics to Universal Design Principles

In the following sections, I’ll describe the UX design principles and usability heuristics that map to specific universal-design principles and guidelines.

Principle 1: Equitable Use

Principle 1 requires that design solutions be useful and accessible to people with diverse abilities. Guidelines that support this principle include the following:

• Providing the same user interactions for all users whenever possible—preferably identical, but at least equivalent interactions.
• Avoiding segregating or stigmatizing users with disabilities.
• Making privacy, security, and safety features equally available to all users.
• Ensuring that design solutions are equally appealing and aesthetically pleasing to all users.

Mapping UXD Principles to UDP 1: Equitable Use

As UX designers, we must strictly adhere to these universal-design principles when defining interactions for digital applications. The following UXD principles map to UDP 1:

• User control and freedom—This principle informs the design of interactions, regulates the amount of freedom to give to users, and better enables users to recover from their mistakes.
• Aesthetic and minimalistic design—Simplicity and an aesthetically pleasing design increase users’ trust in a product and make it easier to use.
• Creating user personas—By conducting user research early on, you can understand your users’ abilities and design for the inclusion of users with disabilities.
• Linguistic clarity and cultural propriety—By capturing users’ demographics, language, and needs during research, you can ensure that interactions accommodate them.
• Forgiveness and responsiveness—This principle ensures that users with all abilities can seamlessly access and safely use software applications.
• Reducing cognitive load—Minimizing cognitive load enables users with cognitive disabilities to use your product. For example, use labels that relate conceptually to functionality.
• Simplifying data-driven tasks—Represent data visually wherever possible, using colors and graphics or icons consistently to improve aesthetics and reduce cognitive load.
• Balancing ease of installation and ease of use—Reduce barriers of entry and simplify common tasks.
• Design trends never trump usability—You can make enormous visual and even behavioral design changes that not only don’t hurt productivity, but can markedly increase it.

“A brilliant solution to the wrong problem can be worse than no solution at all; solve the correct problem.”—Donald A. Norman, The Design of Everyday Things

Principle 2: Flexibility in Use

Principle 2 calls for accommodating a wide range of preferences and abilities. The personas you derive from user research are complete only when they include users with disabilities. Guidelines that support this principle include the following:

• Provide optional methods of interaction.
• Accommodate both right-handed and left-handed access and use.
• Facilitate the accuracy and precision of users’ interactions.
• Adapt to users’ pace of work.

Mapping UXD Principles to UDP 2: Flexibility in Use

The following UXD principles map to UDP 2:

• Flexibility and ease of use—This principle relies on the design of flexible interactions that guide the user and result in simple design solutions.
• Visibility of system status—Convey information about the system’s status to users through stateful user-interface elements that use colors and secondary cues to help communicate state.
• Accuracy and precision—Use clear information displays and precise language to accurately convey information to the user.
• Empowering the user—Ensure that the system functions at the user’s pace.
• Informing the user—Ensure that the user always knows what is happening.

“We must design for the way people behave, not for how we would wish them to behave.”—Donald A. Norman, Living with Complexity

Principle 3: Simple and Intuitive Use

Principle 3 requires creating design solutions whose use is easy to understand for all users, regardless of their experience, knowledge, language skills, or current ability to concentrate. Guidelines that support this principle include the following:

• Eliminate unnecessary complexity.
• Create designs that are consistent with users’ expectations and intuitions.
• Accommodate a wide range of users’ literacy and language skills.
• Arrange information according to its importance.
• Provide effective prompts and feedback to users—both as they complete their tasks and after they’ve completed their tasks.

Mapping UXD Principles to UDP 3: Simple and Intuitive Use

The following UXD principles map to UDP 3:

• Modeling systems on the real world—This lets you define interactions that are simple and easily recognizable to users.
• Reducing uncertainty—Display data in a manner that is clear and obvious to users. This reduces the user’s cognitive load.
• Minimalistic design—Display interactions in ways that keep them handy for users.
• Internationalization—Make careful decisions about what interactions can accommodate multilingual users.
• Consistency and standards—Define interactions that are consistent throughout an application to reduce the user’s cognitive load and improve the user experience.
• Help and documentation—Presenting instructions that help users understand the steps for completing tasks is crucial.
• Reducing complexity—However, any attempt to hide necessary complexity could actually serve to increase an application’s complexity.
• Avoiding the illusion of simplicity—Accept the fact that some application domains must be complex. Do not deceive users about an application’s level of complexity.
• Providing all essential capabilities—Do not simplify an application by eliminating necessary capabilities.
• Allowing feedback—Providing a feature to obtain feedback from users is often essential to improving the user experience of a product or application.

“What makes something simple or complex? It’s not the number of dials or controls or how many features it has; it is whether the person using the device has a good conceptual model of how it operates.”—Donald A. Norman

Principle 4: Perceptible Information

Principle 4 demands that a design clearly and effectively communicate all information necessary for the user, regardless of ambient conditions or the user’s sensory abilities. Guidelines that support this principle include the following:

• Use different modes of communication—including pictorial and verbal information and tactile feedback—to ensure the redundant presentation of essential information.
• Maximize the legibility of essential information by ensuring adequate contrast between essential information and its background.
• Differentiate elements in ways that make it easy for people to describe them—for example, when giving instruction or directions.
• Provide compatibility with a variety of techniques and devices that people with sensory limitations use.

Mapping UXD Principles to UDP 4: Perceptible Information

The following UXD principles map to UDP 4:

• Effective presentation—Presenting information in meaningful ways aids users’ comprehension of that information.
• Thorough testing—Test the usability and accessibility of your visual designs as thoroughly as you do your interactive designs.
• Reporting status—Keep status information up to date and within view.
• Following standards—Consistently adhere to standards such as the Web Content Accessibility Guidelines (WCAG).
• Providing secondary visual cues—Whenever you use color to convey information in a user interface, always provide clear, secondary cues that convey the same information to users who cannot see the colors.
• Conveying information—Precisely conveying information in a user interface to users of all abilities improves usability and enables all users to access that information.

“The design of everyday things is in great danger of becoming the design of superfluous, overloaded, unnecessary things.”—Donald A. Norman, The Design of Everyday Things

Principle 5: Tolerance for Error

Principle 5 requires that design solutions minimize hazards, as well as the adverse consequences of users’ accidental or unintended actions. Guidelines that support this principle include the following:

• Arrange physical elements to minimize hazards and user-interface elements to reduce user errors—especially for those elements that users use most frequently and that are most accessible. Eliminate, isolate, or shield hazardous elements.
• Provide warnings of hazards and potential user errors.
• Provide fail-safe features that protect users from suffering the consequences of errors.
• Discourage unconscious user actions during tasks that require vigilance.

Mapping UXD Principles to UDP 5: Tolerance for Error

The following UXD principles map to UDP 5:

• Forgiveness—Define interactions that make it easy for users to correct their errors or recover lost data.
• Helpful error messages—Messages should be meaningful to users and tell them how to handle the problems they encounter.
• Error recovery—Help users recognize, diagnose, and recover from their errors.
• Error prevention—Even better, prevent users from making errors in the first place.

“The problem with the designs of most engineers is that they are too logical. We have to accept human behavior the way it is, not the way we would wish it to be.”—Donald A. Norman, The Design of Everyday Things

Principle 6: Low Physical Effort

Principle 6 demands that you ensure users can use your design solutions efficiently and comfortably, with a minimum of fatigue. Guidelines that support this principle include the following:

• Ensure that users can maintain a neutral, natural body position when using a product.
• Ensure that users can interact with a product using reasonable operating forces.
• Minimize repetitive actions.
• Minimize sustained physical effort.

Mapping UXD Principles to UDP 6: Low Physical Effort

The following UXD principles map to UDP 6:

• Tempering realism—Model the system after the real world wherever appropriate, but don’t take this too far, making interactions awkward or overly difficult.
• Automation—Automate the user’s workload whenever this would be helpful and the system could perform work more efficiently than the user.
• Providing user assistance—Ensure that the more the user does something, the easier it is to do.
• Minimizing steps—The best user journey is one with the fewest steps. Shorten the distance between users and their goals.
• Minimizing information—Include on a device’s display only the information that the user currently needs.
• Predictability—Provide consistent interactions that help users learn a user interface.
• Efficiency—To maximize the efficiency of a business or other organization, you must maximize everyone’s efficiency, not just the efficiency of the IT department or a similar group.

“Rule of thumb: If you think something is clever and sophisticated, beware—it is probably self-indulgence.”—Donald A. Norman, The Design of Everyday Things

Principle 7: Size and Space for Approach and Use

Principle 7 requires that you provide the appropriate size and space for approach, reach, manipulation, and use, regardless of the user’s body size, posture, or mobility. Guidelines that support this principle include the following:

• Provide a clear line of sight to important elements for any seated or standing user.
• Allow the user to reach to all components comfortably, whether seated or standing.
• Accommodate variations in hand size and grip strength.
• Provide adequate space for the use of assistive devices or personal assistance.

Mapping UXD Principles to UDP 7: Size and Space for Approach and Use

The following UXD principles map to UDP 7:

• Recognition over recall—It’s much easier for users to recognize what they need on a device’s screen rather than trying to recall a command from memory.
• Flexibility and ease of use—Accommodate reduced motor skills, especially those involving gestures.
• Accuracy—Ensure that system-status information is always accurate—especially for VR applications.
• Consistency with standards—This rule improves usability, reduces the coding effort for an application—especially when extending its capabilities—and eases its adaptation to assistive technologies.
• Fitts’s law—The time it takes to acquire a target is a function of the distance to and the size of that target. The time it takes to acquire multiple targets is the sum of the time it takes to acquire each target.
• Legibility—Use font sizes that are large enough to be readable on standard displays.
• Contrast—Text that users must be able to read must have adequate value contrast and, preferably, high contrast.
• Font size—Use a larger font size for the actual data you’re displaying rather than for labels and instructions.
• Clear labeling—In menu commands and button labels, always place the key words first. This usually results in your creating unique labels.
• Usability testing—Be sure to test all of your designs on your oldest target user population.

Conclusion

In this article, I’ve mapped UX design principles to universal-design principles to help you realize both. Following these universal-design principles makes it possible to create physical products or software applications that are accessible to all users, regardless of their different abilities. It is essential that these universal-design principles be implemented in operating systems and user-interface design frameworks for desktop computers, tablets, and mobile devices.

UX designers need to keep an open mind. They must learn to dedicate time during user research to understanding users with disabilities and create personas for the disabled users among their target audience, along with their other target users. User Experience is at its best when it leverages universal design. Many countries are defining specific accessibility guidelines. They are formulating these guidelines with the view of making their country’s services accessible to all users.

As UX designers, we must ensure that our user interfaces are accessible to and easy for users with disabilities to use and enable them to experience the positive emotions that a well-designed user experience provides. Universal-design principles and research have helped the World Wide Web Consortium (W3C) develop and continually revise the WCAG, which shares guidelines for designing accessible user interfaces. But remember: WACG compliance alone is not enough to ensure a complete design solution for people with different abilities. You must learn to empathize with those users during design by conducting early user research. Only achieving full inclusiveness through universal design can ensure your designs meet the needs of all people.