1. General Principles Of Human-computer-interaction

2. Outline Foundations and theories of HCI
Understanding the User Experience
Design principles & guidelines
UX engineering processes
Conclusion

3. Foundations and theories of HCI
Relationship between human users and digital technology
Models: How does a user work, so we can predict how they interact with the UI?
Design new, effective ways for technologies of all purposes
Interaction techniques:
In 2D: standardized
In 3D: ???
There is NO optimal design  tradeoffs
Low-level human processor model Considers also mediation between multiple people through computers
Work and entertainment
Interaction techniques: methods by which a user accomplishes a task
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4. Understanding the User Experience

5. Human Processor Models Basic Idea
Understanding the User Experience
Human Processor Models Basic Idea
Long-Term Memory
Working Memory
Visual Image Store
Auditory Image Store
Perceptual Processor
Cognitive Processor
Motor Processor
Low-level atomic events, transfer & processing of data
Each processor has:
Estimated cycle time
Associated memory
Estimated capacity
Decay time
 Used to estimate human limitations
Human analogous to computers
3 Processors
Perceptual stores sensory stimuli in working memory, Cognitive uses info from working and long-term to make decisions, the motor carries out the decision
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6. Human Processor Model Keystroke-Level Model
Understanding the User Experience
Human Processor Model Keystroke-Level Model
R – respond to motor operator, M – mentally prepare 1+ motor operator, H – home hands, K – perform motor skills, P – point to a target, D – draw a set of straight lines
Easy to use
Task times can be predicted
Evaluation of designs prior development
Only measure time
Considers expert users
Considers error-free executions
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7. Human Processor Model Touch-Level Model (TLM)
Understanding the User Experience
Human Processor Model Touch-Level Model (TLM)
Extensions of KLM to touchscreen and mobile devices, X – naturally occurring distraction, additional: tap, swipe, zoom….

8. Human Processor Model GOMS
Understanding the User Experience
Human Processor Model GOMS
Goals: What does the user want to accomplish? Operators: all actions required to accomplish a goal Methods: specific sequences of actions Selection: method of choice, if more than one option
For 3D UIs: still to be developed
Goal
Selection
Method A
Method B
Operator A1
Operator A2
Operator A3
Operator B1
Operator B2
Takes low-level activities and puts them in four components
Mental workload and fatigue are not addressed
KLM and GOMS include M-like operators for substantial time-consuming mental actions
Human processor models have been used to design and analyze 3D interactions
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9. User Action Models Basic Idea
Understanding the User Experience
User Action Models Basic Idea
High-level interactions between human and system
User’s goal
User’s execution of physical actions
Outcomes of those actions within the system
User’s evaluation of the outcome
Move object
Action plan: reach out and grab
System attaches object to movement of user’s hand
User sees that object moves
Focus on higher –level interactions like forming goals for interaction and perceiving if the goals have been achieved or not
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10. User action model Seven Stages Of Action (User-centric)
Understanding the User Experience
User action model Seven Stages Of Action (User-centric)
Gulf Of Execution
Action Plan
Execution
Perception
Interpretation
Evaluation
Intention
Goal
Gulf Of Evaluation
User determines goal, how is it done (intention), what do I need to do to use the tool (action plan), will use the tools (execution - User affects system
SYSTEM gets input and determines outcome
User sees outcome (perception), tries to understand it (interpretation) and rates it if true/false (evaluate)  System informs User about its state
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11. User action Model User Action Framework (USer-centric)
Understanding the User Experience
User action Model User Action Framework (USer-centric)
Based on Seven Stages
How to do it?
Partitions seven stages into five phases
Planning: Goal + Intention
Translation: Action Plan
Physical Actions: Execution
Outcomes: Internal to system, Outcomes
Assessment: Perception, Interpretation, Evaluation
Do it.
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12. User Action Model User-System Loop (system-centric)
Understanding the User Experience
User Action Model User-System Loop (system-centric)
For 3D UIs!!!
perceived by
create
manipulate
Sends commands to
Adaption of seven stages (2015)
updates
alter
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13. Conceptual Models and Affordances
Understanding the User Experience
Conceptual Models and Affordances
Conceptual models: understanding of the information and tasks that constitute a system
Designer’s model: how the designer understands the system
User’s model: how the user understands the system, based on experience
If designer model = user model  high level of usability
Affordance:
Increases the likelihood of user model = designer model
Cognitive, physical, functional & sensory
3D UIs: importance of physical affordance
Action models portray interactions between user & system
Conceptual models: how do the users expectations match the systems expectations?
understanding of the information and tasks that constitute a system
Affordance: something that helps the user to do something
Cognitive: erase with an eraser tool, physical: eraser tool in reach?, functional: eraser tool affords the functionality of removing the object, sensory: haptic feedback when object touched
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14. Activity Theory Activity theory: S (activity) O Object-oriented
Understanding the User Experience
Activity Theory
Interactions occur in real world, including other humans, systems, objects & activities
“ecological perspective” of UX
Tool for analyzing user interactions in VR
Activity theory:
S (activity) O
Object-oriented
Subject: person/group in activity
Object: motive, that needs the meet of S
Activity system model:
Community as 3rd element
VR as tool to mediate the user’s ability to accomplish goal
Activities carried out by collective subjects
User (subject) uses a visual display (object) to view a virtual world (activity).
Activity system models: extension
Look at intruments, rules in communities change the relationship of user-object activity
Tool for designing and evaluating 3D UIs
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15. Embodied Interaction Tangible Computing:
Understanding the User Experience
Embodied Interaction
Familiar real-world aspects
computer systems interacting in our physical and social reality
“the creation, manipulation, and sharing of meaning” – Dourish (2011)
Tangible Computing:
Users interacting with digital information through the physical environment
Social Computing:
Any type of system that serves as a medium or focus for social relation
Related to activity theory
3D UIs: Telepresence
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16. Design Principles and guidelines

17. Aspects Goal-Oriented Execution-Oriented Outcome-Oriented
Design Principles and Guidelines
Aspects
Goal-Oriented
Execution-Oriented
Outcome-Oriented
Evaluation-Oriented
Four aspects from the User Action Model
Organized by the four distinct aspects of the user action models
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18. Goal-Oriented Design Principles and Guidelines Simplicity Structure
Simple and task focused
Eliminate extraneous or redundant information (use filters)
Structure
Organized in a meaningful and useful way
Break down complex tasks into subtasks
Visibility
Self-explaining function of control
Employ familiar and recognizable visual icons and symbols
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19. Execution-Oriented Design Principles and Guidelines Affordance
Self-explanatory use of control
Leverage familiarity with common UIs
Direct manipulation
Consistency
Ergonomics
Clearance, Reach, Posture, Strength
Error Prevention
Permit only valid actions
Confirm irreversible actions
Offer common outcomes (autocomplete)
How does the user specify and execute action plans?
Prevent difficulties
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20. Outcome-oriented Design Principles and Guidelines Automation Control
Offer common outcomes (autocomplete)
Avoid tedious interactions
Interaction methods to complete series of similar actions in parallel
Control
Too much automation  too little automation
Confirm feature for autocomplete
Provide features for novices & experts
Keep creativity of users in mind (avoid missing or incorrect functionality)
System should need as little input as possible for common tasks
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21. Evaluation-Oriented Feedback Error Recovery
Design Principles and Guidelines
Evaluation-Oriented
Feedback
Prominent for infrequent or major actions
Provide informative feedback (simple, comprehensible error messages)
Error Recovery
Help user to recognize, diagnose & recover from errors
Provide easy-to-reverse actions
Controls to reverse the outcome
Outcome has to be shown in a way that the user can see if it is right or wrong
Also make it ease to quickly recover from wrong outcomes
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22. General Rules Design Principles and Guidelines Accessibility
For disabled persons (vision-, hearing, and/or mobility-impaired)
Vocabulary
Use vocabulary of intended user
Recognition
UI should provide knowledge required for operating the UI
Recalling is much more difficult!
Let users know what their options are
Use pictures and visual representations
Important at every stage of interaction
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23. Ux eNGINEeRING

24. Revisit previous activity
UX Engineering
Aspects
Goal?
System Goals and Concepts
Requirements Analysis
The Design Process
Prototyping
Evaluating Prototypes
Analyze
Design
Implement
Evaluate
Revisit previous activity

25. System Goals and Concepts
UX Engineering
System Goals and Concepts
Improving Usability
Effectiveness, efficiency, satisfaction
Learnability, Retainability, Ease of Use, Speed of performance, Rate of errors, User comfort
Usefulness
System that provides functionality and serves a purpose
Emotional Impact
 especially powerful in 3D UIs
What is the reason behind developing the UI???
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26. Requirements Analysis
UX Engineering
Requirements Analysis
Inquire & analyze the context
Extract the requirements
Functional (what?)
Performance (how?)
Interface (which characteristics?)
What are the needs of the intended user?
Interface requirements: What characteristics should it have?
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27. The Design Process Design Tools Design Perspectives Design Approaches
UX Engineering
The Design Process
Design Tools
Ideation, Sketching, Critiquing
Design Perspectives
Interaction, ecological, emotional
Design Approaches
Activity, Information, Interaction
Design Representations
Metaphors, design scenarios, storyboards, physical mockups
Identify good design ideas
Design tools to explore design options
Design perspectives: interaction ( user action model), ecological ..how used in its surrounding environ… (activity theory), emotional (basic human processor model)
Approaches: activity design (focus on system functionality & supported activities)
information design (focus on representing & arranging the UI, evaluation)
interaction design (focus on mechanisms for accessing and controlling the UI)
Design scenarios: story about people using it, storyboard: sequence of drawings, mockup: tangible 3D prototype
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28. Prototyping Communicate planned functionality and design
UX Engineering
Prototyping
Communicate planned functionality and design
Number & functionality of features  different combos  different prototypes
Level of fidelity
Level of interactivity
Fidelity: how close to reality?
Interactivity: : video demonstration or fully programmed and usable?
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29. Evaluating Prototypes
UX Engineering
Evaluating Prototypes
Formative (during the process) Rapid (cognitive walkthroughs & heuristic methods) Analytic (analyzing inherent attributes of design)
Summative (during final iteration)
Rigorous (formal, systematic methods)
Empirical (observing users)
vs.
Methods to evaluate the prototype
Rapid: fast & Easy
Rigorous: expensive in time and resources, more informative
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30. Conclusion What we learned: Applied to 3D UIs:
Models to understand the user
Designs and guidelines to make user- friendly UIs
Engineering the UX
Applied to 3D UIs:
 most 2D UI models applicable to 3D UIs, still research potential
 no standardized way of doing things
 more focus on emotional and physical impact
 Iterative process, also for 3D UIs