Checklist: Heuristic Principles for Usability 1
To conduct an heuristic evaluation of a service offered through the web, travel through the pages of the site, reflecting on each of the listed principles, and recording compliance and violations. The heuristic principles should also be kept in mind during cognitive walkthroughs.
Visibility of system status
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
Match between system and the real world
The system should speak the user's language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
User control and freedom
Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
Recognition rather than recall
Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
Flexibility and efficiency of use
Accelerators - unseen by the novice user - may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
Aesthetic and minimalist design
Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
Help users recognize, diagnose, and recover from errors
Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
Help and documentation
Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.
More detail on each of the principles can be found in be found in an expanded list from Deniese Pierotti of Xerox, which itemizes specific things to look for when evaluating a system with Nielsen's Heuristics. See Heuristic Evaluation - A System Checklist.
Heuristic Principles for Accessibility
The Fluid UX Accessibility Working Group has created a set of protocols for assessing accessibility:
- Simple Accessibility Walkthrough Protocol: This is a set of simple heuristics for evaluating the general accessibility of a web application without need for complex assistive technologies. It provides a simple technique that anyone can learn while doing UX Walkthroughs.
A paper from Claire Paddison and Paul Englefield provides a list of nine heuristic principles for accessibility evaluations:
- Applying Heuristics to Perform a Rigorous Accessibility Inspection in a Commercial Context
(Click on the Full Text PDF link and view pages 129-130.)
Paddison and Englefield include in their paper a general discussion of the heuristic approach. This is recommended reading for all reviewers.
1 The above section lists the original Nielsen and Molich heuristics, as refined by Nielsen.