代写代考 COSC2628 User

COSC2628 User
Centred Design
Week 3: Usability and Design Principles, Heuristic Evaluation

RMIT University acknowledges the people of
the Woi wurrung and Boon wurrung
language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University.
RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians
and their Ancestors of the lands and waters across Australia where we conduct our business.
Ngarara Place

User interface hall of shame: What’s wrong with this picture?
5 minute breakout groups

User interface hall of fame: What’s right with this picture?
5 minute breakout groups

Learning objectives
Understand Nielsen’s principles
Learn the basics of heuristic analysis
Understand some design principles based on Nielsen

User Centered Design:
• https://www.youtube.com/watch?v= 90yW0vQpKVs

Part 1: Nielsen’s Principles

Who is Nielsen?
• Developed the most used heuristics for interface design in 1990 with .
• main heuristics released in 1994.
• Has a consulting group for usability: http://www.nngroup.com/articles/te n-usability-heuristics/

Why ‘heuristics’?
These are not specific rules
More like rule of thumb
Not mutually exclusive
Usability issues can’t be pigeonholed

Nielsen’s 10 principles
Visibility of system status
Match between system and the real world
Error prevention
Recognition rather than recall
User control and freedom
Flexibility and efficiency of use
Consistency and standards
Aesthetic and minimalist design
Help users recognize, diagnose and recover from errors
Help and documentation

1 Visibility of system status
• User should always be informed of what is happening behind the scenes, when appropriate.
• For example, when uploading a file there should be a progress bar.
• In general always tell the user what is happening if they have no control.
• Keyword here is when appropriate and necessary. No need to bombard your users with your servers’ CPU cycles.

1 Visibility of system status
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2 Match between real world and system
• The system should speak users’ language
• Use familiar metaphors, e.g. envelope for email
• If a niche product make sure to use words that your market recognises
• Use logical and instinctive phrases and graphics.

2 Match between real world and system
Which is better? Why? (5 minutes)

3 User control and freedom
Escape hatches for users are important.
Allow users to exit state without extended dialogue, but do warn of consequences (e.g. shopping cart)
Supporting redo and undo functions.

4 Consistency and standards
• Use the same words to mean the same thing • Example: ‘Exit’ and ‘Log out’ or even ‘Leave’
• Navigation should be consistent • Follow platform conventions.

4 Consistency and standards

5 Error prevention
• Anticipate common mistakes and prevent them
• Example: number keypads for entering phone numbers.
• Confirmation dialogues may be useful before users do anything irreversible

5 Error prevention
From Seminara, Gonzales, & Parsons, 1977. Photograph courtesy of . Seminara.

5 Error prevention
Picture: Frankfarm (Creative Commons)
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6 Recognition rather than recall
Instructions to use your system should be easily visible and followed.
What is possible should be readily visible Don’t expect users to memorise functions
Use layout, graphics and design to ensure that functions are easily identified.

6 Recognition rather than recall

6 Recognition rather than recall
• What do you type?

6 Recognition rather than recall
What do you say to these?

7 Flexibility and efficiency of use
Shortcuts for expert users
Functionality based on user skills
Help for novice users, accelerators for experts
User accounts and settings drive experience

7 Flexibility and efficiency of use

8 Aesthetics and minimalist design
Do not clutter!
Every element should be vital Avoid overwhelming your users
Funnel your users, don’t blanket them with functions.

8 Aesthetic and minimalist design
Google 2015 and now

Design is cultural! Shanghai Jiao-

9 Recognize, diagnose and recover
• Error messages should be: –phrased in clear & natural
–constructive: offer alternatives
–polite; do not intimidate or blame the user

9 Recognize, diagnose and recover
• Good error messages help the user to
–resolve their problem
–learn more about the system

Bad error messages
WinSCP error message
RMIT University©2020 CS&IT 34
Remmina Remote Desktop, Ubuntu

10 Help and documentation
Help is the last resort
If help is needed, the user is already frustrated, help must be: • Easy to locate
• Contextual where possible.

10 Help and documentation

Heuristic Evaluation
“Heuristic evaluation (Nielsen and Molich, 1990; Nielsen 1994) is a usability engineering method for finding the usability problems in a user interface design so that they can be attended to as part of an iterative design process. Heuristic evaluation involves having a small set of evaluators examine the interface and judge its compliance with recognized usability principles (the ‘heuristics’).”
https://www.nngroup.com/articles/how-to-conduct-a-heuristic-evaluation/

Heuristic Evaluation
• No single set of Heuristics. Nielsen famous, but there are also others:
–Bastien and Scapin created a set of 18 Ergonomic criteria –Gerhardt-Powals’ 10 Cognitive Engineering Principles
–Connell & Hammond’s 30 Usability Principles
–Smith & Mosier’s 944 guidelines for the design of user-interfaces (from 1986)
(http://www.measuringu.com/blog/he.php )

Applying Heuristics
• Usability violation of heuristic(s)? Assign a severity. • 0 = no problem to
• 4 = usability catastrophe
• Table of issues and severity.
• Issues fixed according to ease of fix and severity

Effectiveness
From: Nielsen, J., & Molich, R. (1990). Heuristic evaluation of user interfaces. In Proc CHI (pp. 249-256)
• 5 analysts trap
• 75% of all problems
• >90% of serious problems
• Same results for 2 domain expert analysts

Pros and Cons
• Inexpensive
• Early feedback
• Requires multiple experts
• May require additional usability testing

More Heuristics: Shneiderman’s Eight Golden Rules
“Designing the User Interface: Strategies for Effective Human-Computer Interaction”,
• Strive for consistency
• Enable frequent users to use shortcuts
• Offer informative feedback
• Design dialogue to yield closure
• Offer simple error handling
• Permit easy reversal of actions
• Support internal locus of control
• Reduce short-term memory load https://www.interaction-design.org/literature/article/shneiderman-s-eight-golden-rules-will-help-you-design-better-interfaces

How Shneiderman’s 8 Golden Rules
Consistency

How Shneiderman’s 8 Golden Rules

How Shneiderman’s 8 Golden Rules
Informative Feedback

How Shneiderman’s 8 Golden Rules

How Shneiderman’s 8 Golden Rules
Permit reversal of actions

How Shneiderman’s 8 Golden Rules
Error Handling

How Shneiderman’s 8 Golden Rules
Support internal locus of control

How Shneiderman’s 8 Golden Rules
Reduce short-term memory load

Evaluating your interface using Schneiderman’s 8 Golden Rules
Worksheet PDF: https://public- media.interaction- design.org/pdf/Shneiderman.s.Eight. Golden.Rules.Worksheet.pdf

Quiz time: Code is to Quizzes in Canvas, and complete Quiz 2

Part 2: Design Principles

Design Principles? Heuristics?
Heuristics
Abstract Focus on cognition
Design Principles
Specific Concrete Focus on interaction

How to use
Understand context
• Type of system
• Type of user
• Context of use
Guidelines, not rules!

Principle of proximity
Also known as the grouping principle.
Objects near each other do related things
Navigation particularly affected
e.g. “no” will be next to “yes”

Proximity example

Visibility and visual feedback
Prominence
Colour/contrast

Often used to bring items into focus without losing context

Colours/contrast
Higher contrast or brighter colours will draw more attention.
You’ll read this
Before this
RMIT University©2020 CS&IT

Affordance
Cues for use

Doors again

What is the system doing? • Waiting for input?
• Processing?

Consistency
Internal consistency: Ensuring like things in your interface look similar
• Position of functions
• Style/font/colours
• Language (log in vs. sign in)
External consistency: employing the conventions of similar interfaces
• Design patterns
• Interface element placement
• Language

What’s wrong with this picture?

Hick’s law
• Amathematicalformula describing how long it will take users to choose the item from a set of items.
• More items to choose from -> longer time.
• Time increases logarithmically

Hick’s Law

Fitts’ law
A mathematical formula that models how accurate users will be when moving the cursor between objects (e.g. buttons) on screen.
▪ Further apart -> less accurate.
▪ It’s faster to hit larger targets closer to you than smaller targets
further from you.
▪ Found to work with touch interfaces

Fitts’ law

• Nielsen’s 10 principles
• How to do a Heuristic Analysis • Shneiderman’s 8 golden rules • Design principles

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