ITSD 4303 HumanComputer Interaction

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ITSD 4303Human-Computer Interaction

• Principles of User-Centered Design
• DET (187-207)

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Agenda

• Usability defined
• Mental Models revisited
• Software Development Users
• Learnability Paradox
• Unfolding

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Three Words

• Utility
• Capability
• Usability

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Three Words

• Utility - does it fulfill a need?
• Capability - does it do it?
• Usability - ???

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Usability Defined

• Is the system easy to learn?
• Learnability
• Rememberability
• Is the system easy to use?
• Efficiency
• Reliability
• Satisfaction with experience

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When Mental Models Collide

• Youre writing software
• Youve got a vision of how it should work
• It makes sense to you

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When Mental Models Collide

• Youre using software
• Youve got a vision of how it should work
• What was the programmer thinking?

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When Mental Models Collide

• Youre maintaining/supporting software
• Youve got a vision of how it should work
• What was the designer thinking?
• What is this idiot user thinking?

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Bridging the Gap
The Designer
The User
The System
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Bridging the Gap
The Designer
The User
The System
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A Simple Exercise in Requirements Gathering

• Group into 3-4 people
• Come up with a transportation system
• Describe
• What to transport
• Number of items transported
• Speed
• Cost
• Power Source

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The Alternative

• Avoid the customer
• They just keep making my job harder
• Assume that you know whats needed
• You know what they say about assuming?

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Interface vs. Implementation
TheUser
TheDesigner
TheImplementation
TheInterface
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What Users See Design
TheUser
TheDesigner
TheImplementation
TheInterface
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Needful Things

• Users dont care about
• Nifty algorithmic solutions
• All the work it took to create the software
• Users do care about
• Getting their job done
• The interface that the software presents

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What Users See Models
TheUser
TheDesigner
TheImplementation
TheInterface
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Needful Things 2

• Users dont care about
• Complex visual models
• All the work it took to create the model
• Users do care about
• Clear models
• Multiple views of the system (zooming)
• Speaking a common language

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Precedence

• It would be natural to shape the users mental
  models to conform to the system
• But better is a system designed to work with
  existing mental models
• Leverage whats there already!

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Mental Model Example

• E-mail - is it like a fax machine or the
  traditional postal system?

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Usability Rules

• Establish a compass, or guidelines which will
  help lead to better usability
• They dont guarantee success
• In the hands of the inept, all can still go wrong

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Usability Rules

• Access
• Efficacy
• Progression
• Support
• Context

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Access

• Usable, without help or instruction
• Assumes knowledge and experience in the
  application domain
• No prior experience with the system
• The Holy Grail - intuitive
• Help manuals on-line?
• Handle wrong actions gracefully

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Efficacy

• Dont hold back experienced users
• Shortcut keys, for example
• Often in conflict with the rule of accessibility

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Progression

• Make learning the system easy
• Move users from beginners to experts
• Modify UI as the user gains proficiency
• The helpful paperclip, for example
• Smooth, self-paces progression needed

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Support

• Make real work
• Easier
• Simpler
• Faster
• More fun
• More possibilities
• Dont miss the forest for the trees

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Context

• Make the system usable in the environment in
  which it will be used
• Run the software on the users machines
• Sound, color, etc. come into play here

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UI Design Principles

• The rules specify a course to take
• The principles are more focused and deal with
  details

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UI Design Principles

• Structure
• Simplicity
• Visibility
• Feedback
• Tolerance
• Reuse

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Structure

• Organize the UI
• Clear consistent models
• Put related things together
• Make related items look similar
• Separate unrelated items

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Structure Example
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Simplicity

• Make common tasks easy
• Talk the users talk
• Provide shortcuts
• Assumes you know which tasks are common!
• Defaults Wizards help here

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Visibility

• Show whats needed
• Hide redundant/unneeded info
• WYSIWYN
• Customized toolbars
• Self-hiding menus

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Feedback

• Inform the user appropriately
• Progress meters
• Animations
• Mouse cursors
• Status bars, window titles
• Informative error messages

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Tolerance

• Reduce the cost of mistakes
• Provide undo/redo capability
• Requires more work on the designer/implementer
• Parsing page numbers, for example

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Reuse

• Maintain consistency with standard interfaces
• Makes tasks more easy to remember
• Makes tasks faster
• This is one of the secrets to Microsofts success
  - standard dialogs and widgets

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Benefits of Reuse

• Cost reduction
• Improved interface
• This is different from standards or consistency
  as a rule b/c reuse forces these without the
  repetitive implementation

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Putting it into Practice

• Use of the system is tell-tale
• Users will discover minor, yet critical details
• The users are the customers see your job as
  being their advocate

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Wanna Move Your Money?

• Major bank designing web site
• Months of development
• Site was horribly designed
• Users complained
• Then the bright idea
• Why not talk with the users!

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More than Communication

• Theres more to developing software than talking
  with the customer
• What about all the other parts
• Learn more in TQA
• Well focus on testing

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Types of Testing

• Implementation/module
• Integration
• System
• Beta
• Alpha
• Usability

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The Trouble with Traditional Testing

• Lacks maneuverability
• Comes late in the game
• Architectural changes often not possible
• Cost is increased

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Cost of Changes
Cost
Deployment
Time
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Too Early?

• Can testing even be done earlier?
• Code isnt implemented yet
• System isnt completed
• So is it possible?

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Enter RAD

• Rapid Application Development
• Modern APIs such as VCL and MFC
• IDEs like Delphi, VB, and Visual C
• Prototype your way to success

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Prototype, You Say?

• Some warn against this approach
• Rightly so - it can fail
• But it offers promise if done correctly

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The MS/AOL Philosophy

• Always have something to show
• The softwares success is defined by the users
  experiences
• So easy to use, no wonder theyre 1

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The Best Approach

• Involve the user at all phases of the project
• From the beginning, focus on the use of the
  product
• Get over the technology!

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Usage-Centered Design

• Shift of focus from technology to people, from
  user interfaces to users.
• Focus on the work that users are trying to
  accomplish and on what the software will need to
  supplyto help them accomplish it

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Tools of the Trade

• Abstract models
• Stay away from implementation details
• Similar to brainstorming
• Multiple views

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The Learnability Paradox

• Weve got to make our system easy to learn
• Novices need help
• Novices need handholding, examples, etc.
• Weve got to make our system productive from day
  one
• Experts want complete access control
• Experts dont want distractive help pop-ups

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Manuals?

• Do the help?
• Sometimes a well-written manual can help a new
  user
• Reference cards help experts
• Most users arent willing to read pages of text
  before using the software, though!

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Common Solutions

• First-time hints window
• Provides helpful clues for system use
• Can be disabled
• Wizards
• Provides a way of quickly filling in defaults
• Help complete complex tasks

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FIN