User Interface Guidelines
Guidelines and best practices to keep in mind when designing interfaces for interactive applications.
Many people have developed guidelines (a.k.a. “heuristics”) for interactive applications — general rules of thumbs for how interfaces should look and behave. Some of these are based on scientific user research while others are based on years of experience developing interfaces.
We have summarized the some of the most important guidelines below.
These guidelines are high-level and they are not set in stone. Every interface project is different: the tasks its users need to perform vary; the specific goals of the application (such as task efficiency, learnability, or enjoyment) dictate the direction the interface takes; and the users’ background and environment have a huge bearing. So, network management software designed for systems administrators in the workplace will look and act very different than shopping list software designed for general use on a mobile device, or a knowledge base for medical researchers. The practical constraints of budget, time, and available technology will also impact what is and is not doable in an interface.
The guidelines also evolve over time, as users grow accustomed to new interface conventions and as technology changes.
Jakob Nielsen’s 10 Usability Guidelines
Our summary:
- Visibility of system status
Keep users informed about what is going on - Match between system and the real world
Speak the user’s language; use familiar conventions - User control and freedom
Support undo and redo; provide emergency exits - Consistency and standards
- Error prevention
Design the system to minimize the amounts of errors that could occur - Recognition rather than recall
Minimize what the user needs to remember, from screen to screen - Flexibility and efficiency of use
Design the system to work both for novice and expert users - Aesthetic and minimalist design
Eliminate elements that are not necessary - Help users recognize, diagnose, and recover from errors
- Help and documentation
Provide help as needed; make sure the help system itself is usable — focused on the user's tasks and easy to peruse.
Details:
www.useit.com/papers/heuristic/heuristic_list.html
Shneiderman & Plaisant’s 8 Golden Rules
These guidelines are very similar to Nielsen’s.
Our summary:
- Strive for consistency
- Cater to universal usability
Users vary in their abilities, in their domain knowledge, and in how they process information. Where possible, provide features for your diverse range of users. - Offer informative feedback
When user or system take an action, show appropriate feedback (modest or pronounced, depending on the situation) - Design dialogues to yield closure
Sequences of actions should have a clear start and end - Prevent errors
Design the system to minimize the amounts of errors that could occur. When errors occur, make it easy for the user to recover. - Permit easy reversal of actions
Wherever possible, support undo and redo - Support internal locus of control
Make the user feel like they are in control — not the system. The interface should respond to their actions; the system should not perform surprising actions or make it difficult to get tasks done or find information. - Reduce short term memory load
Minimize the amount of information your users need to remember from screen to screen
Details:
Shneiderman, B., & Plaisant, C. (2005). Designing the User Interface: Strategies for Effective Human-Computer Interaction (4th, pp. 74-76). Boston: Addison-Wesley.
Fitts’ Law
Fitts’ Law says that the time for hand movements is dependent on distance and target size. The farther your cursor currently is from the next place you want to move it to, the longer it will take you to perform that action. And the smaller the target, the more difficult it will be to click on it. Fitts’ Law provides a model to measure that performance.
For example, if the submit button is very far away from the last entry field in the form or it is very small, it will take longer for people to submit the form. Fitts’ Law is important to keep in mind if your goal is to decrease task time for repeat users.
Hick’s Law
Before you move your cursor or take any an action, you must first choose the target or action — and this takes time. Hick’s Law provides a model to measure that decision time.
To summarize:
- Making decisions takes time
- Making complex decisions will take more time than simpler ones
- Large number of choices will take more time than a small number
- Giving the user many choices simultaneously is usually faster than organizing the same choices into hierarchical groups
Of course, you need to balance this against other guidelines. Simplifying the choices to speed up your user’s task time might result in more errors. Showing a huge list of choices up front might overwhelm the user.
Jef Raskin’s 3 Cardinal Rules
- A computer shall not harm your work or, through inaction, cause your work to come to harm
- A computer shall not waste your time or require you to do more work than is strictly necessary
- Users should set the pace of interaction
Details: Raskin, J. (2005). The Humane Interface: New Directions for Designing Interactive Systems. Boston: Addison-Wesley Professional. (Original work published 2000).
Usability.gov’s Research-Based Guidelines
These guidelines are more specific than the other guidelines we have mentioned. They apply mostly to informational Web-based sites (as opposed to interactive software or sites viewed on mobile devices). The guidelines were compiled by the federal government; they were supported by usability research findings and prioritized by a group of experts.
Their top guidelines:
- Provide useful content
- Establish user requirements
- Understand and meet user’s expectations
- Involve users in establishing user requirements
- Do not display unsolicited windows or pop-up graphics
- Comply with Section 508 (the government’s accessibility guidelines)
- Design forms for users using assistive technology
- Do not use color alone to convey information
- Enable access to the home page
- Show all major options on the home page
- Create a positive first impression of your site
- Avoid cuttered displays
- Place important items consistently
- Place important items at top center
- Eliminate horizontal scrolling
- Use clear category labels
- Use meaningful link labels
- Distinguish required and optional data entry fields
- Label pushbuttons clearly
- Make action sequences clear
- Organize information clearly
- Facilitate scanning
- Ensure that necessary information is displayed
- Ensure usable search results
- Design search engines to search the entire site
More guidelines and complete details:
www.usability.gov/pdfs/guidelines.html
Also available in a printed book.
