In psychology, heuristics are simple, efficient rules which people often use to form judgments and make decisions. They are mental shortcuts that usually involve focusing on one aspect of a complex problem and ignoring others.
Jakob Nielsen defined 10 general principles for interaction design. These were;
1. Visibility of system status:
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
One good example is the “egg timer logo” which displays while a system action is being run in the background and the user is waiting for a response.
2. Match between system and the real world
The system should speak the users’ 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.
A bad example of this is where a website displays a message that simply says “Error 404 Page not Found”. Most people won’t understand what this means!
3.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.
Example – display a “back” or “undo” button to allow users to easily correct a mistake they have made, or present a dialogue box to explain the effect of a requested action and re-confirm the action requested, e.g. ” this will delete all of the files – are you sure you wish to proceed? Yes / No.
4. Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
Example – if people are used to the colour RED signifying “danger” and the colour GREEN signifying “safety”. Don’t use the colours in teh wrong context.
5. Error prevention
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.
6. 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.
7. 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.
Example is use of “Control” and “Z” keys to undo an action or “Control” and “S” keys to save.
8. 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.
Quite often, “Less is More”.
9. 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.
A good example is the auto correct tool used by word processing packages which can identify incorrect spelling or possible grammatical errors and offer alternatives.
10. 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.
Many packages will have a “?” or an “i” button to indicate the availability of support and documentation.