Usability Heuristics

Usability Heuristics CMPT 281

Outline Usability heuristics Heuristic evaluation

Usability heuristics • Heuristics: • rules of thumb that describe features of usable systems • As design principles: • broad usability statements that guide design efforts • derived by evaluating common design problems across many systems • As evaluation criteria: • the same principles can be used to evaluate a system for usability problems • becoming very popular • user involvement not required • catches many design flaws

Usability heuristics • Advantages • the minimalist approach • a few guidelines can cover many usability problems • easily remembered, easily applied with modest effort • discount usability engineering • cheap and fast way to inspect a system • can be done by usability experts and end users • Problems • principles are at the ‘motherhood’ level • can’t be treated as a simple checklist • there are subtleties involved in their use

Nielsen’s Ten Heuristics • Visibility of system status • Match between system and the real world • User control and freedom • Consistency and standards • Error prevention • Recognition rather than recall • Flexibility and efficiency of use • Aesthetic and minimalist design • Help users recognize, diagnose, and recover from errors • Help and documentation

Visibility of system status • The system should always keep users informed about what is going on • Appropriate feedback within reasonable time

Visibility of system status What mode am I in now? What did I select? How is the system interpreting my actions?

Visibility of system status

Match between system and real world • The system should speak the users' language • Words, phrases and concepts familiar to the user • Not system-oriented terms • Follow real-world conventions • Put information in a natural and logical order

Match between system and real world

User control and freedom • Users often choose system functions by mistake • They need clearly marked “emergency exits” • Let them get back without extended dialogue • Support undo and redo

User control and freedom

Consistency and standards • Users should not have to wonder whether different words, situations, or actions mean the same thing. • Follow platform conventions

Consistency and standards Ok Cancel Cancel Ok Done Never Mind Accept Dismiss

Consistency and standards

Error prevention • Even better than good error messages is a careful design which prevents a problem from occurring in the first place. • Two options: • Eliminate error-prone conditions • Check for them and present users with a confirmation option before they commit

Error prevention

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

Recognition rather than recall

Flexibility and efficiency of use • Accelerators can speed up interaction for expert users • Accelerators are unseen by the novice user • The system can cater to both inexperienced and experienced users • Allow users to tailor frequent actions.

Flexibility and efficiency of use

Aesthetic and minimalist design • Dialogues should not contain information that is irrelevant or rarely needed • Every extra unit of information in a dialogue competes with relevant units, and diminishes their visibility

Help users recognize, diagnose, and recover from errors • Error messages: • Should be expressed in plain language (no codes) • Should precisely indicate the problem • Should constructively suggest a solution

Help users recognize, diagnose, and recover from errors

Help and documentation • Best if the system can be used without help! • May be necessary to provide help and documentation • Help should be: • Brief • Easy to search • Focused on the user's task • Concrete

Help and documentation

Neilsen’s Nine Heuristics • 1. Simple and natural dialog • 2. Speak the user’s language • 3. Minimize user’s memory load • 4. Be consistent • 5. Provide feedback • 6. Provide clearly marked exits • 7. Provide shortcuts • 8. Deal with errors in a positive manner • 9. Provide help

1. Simple and natural dialogue • Use the user’s conceptual model • Match the users’ task in a natural way • minimize mapping between interface and task

1. Simple and natural dialogue • Present exactly the information the user needs • less is more • less to learn, to get wrong, to distract... • information should appear in natural order • related information is graphically clustered • order of accessing information matches user’s expectations • remove or hide irrelevant or rarely needed information • competes with important information on screen • use windows frugally • don’t make navigation and window management excessively complex

2. Speak the users’ language • Terminology based on users’ language for task • e.g. withdrawing money from a bank machine

2. Speak the users’ language • Use meaningful mnemonics, icons, and abbreviations • eg File / Save • Ctrl + S (abbreviation) • Alt FS (mnemonic for menu action) • Open folder (toolbar icon)

2. Speak the users’ language

3. Minimize user’s memory load • Promote recognition over recall • Computers good at remembering things, people aren’t! • menus, icons, lists vs. command lines, field formats • relies on visibility of objects to the user (but less is more!)

3. Minimize user’s memory load • Input formats • Indicate required format • give example and default entry

3. Minimize user’s memory load • Small number of rules applied universally • generic commands • same command can be applied to all interface objects • interpreted in context of interface object • copy, cut, paste, drag and drop • for characters, words, paragraphs, circles, files

4. Be consistent • Consistency of effects • the same words, commands, and actions should always have the same effect in equivalent situations • increases predictability • Consistency of language and graphics • same information and controls in the same location • forms should follow boiler plate • use the same visual appearance across the system • e.g. icons, UI widgets • Consistency of input • consistent syntax across system Ok Cancel Cancel Ok Done Never Mind Accept Dismiss

> Doit > Doit This will take5 minutes... 5. Provide feedback • Continuously inform the user about: • what the system is doing • how the system is interpreting the user’s input • The user should always know what is going on What’s it doing? Time for coffee.

5. Provide feedback What mode am I in now? What did I select? How is the system interpreting my actions?

5. Provide feedback • Be specific, based on user’s input • Interpretation of feedback: • Simpler when in the context of the action

5. Provide feedback • Response time • how users perceive delays • 0.1 second: perceived as instantaneous • 1 second: user’s flow of thought stays uninterrupted, but delay noticed • 10 seconds: limit for keeping user’s attention focused on the dialog • > 10 seconds: user will want to perform other tasks while waiting

5. Provide feedback • Dealing with long delays: • Cursors/Throbbers • for short transactions • Percent done dialogs • for longer transactions • how much left • estimated time • what it is doing… • Random animation/Throbber • for unknown times Contacting host (10-60 seconds) cancel

6. Provide clearly marked exits How do I get out of this?

6. Provide clearly marked exits • Users don’t like to feel trapped by the computer! • offer an easy way out of as many situations as possible • Strategies: • Cancel button (for dialogs waiting for user input) • Universal Undo (can get back to previous state) • Interrupt (especially for lengthy operations) • Quit (for leaving the program at any time) • Defaults (for restoring a property sheet)

Usability Heuristics