HCI Frameworks
How we conceptualize users of
computing systems
Human Role
• How is human viewed in HCI
– What is human role?
• Different roles engender different frameworks
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Human Roles
Human considered to be a…
• 1. Sensory processor
– Experimental psych, sensory psych
• e.g. Model-Human Processor (Card, Moran & Newell)
• 2. Interpreter/Predictor
– Cognitive psych, AI
• e.g. Distributed cognition (Hutchins)
• 3. Actor in environment
– Activity theory, ethnography, ecol psych
• e.g. Situated action (Suchman)
• e.g. Activity theory (Vygotsky, Nardi)
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What Makes a System Usable
Human considered
to be a…
Usability results when the
system…
Sensory processor
Fits within human limits
Interpreter/Predictor
Fits with knowledge
Actor in environment
Fits with task and social
context
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Evaluation Methods
Human considered
to be a…
Evaluation methods…
Sensory processor
Quantitative experiments
Interpreter/Predictor
Task analysis, cognitive
walkthrough
Actor in environment
Ethnographic field work,
participatory design
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Two Views of Interaction
• Interaction with
– Software system is a tool or machine
– Interface is a usability-engineered membrane
– Human-as-processor & -interpreter models
• Interaction through
– Software is a medium used to interact with task objects or
other people
– Interface plays a role in social context
– Human-as-interpreter & -actor models
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What are Humans Really Like?
• Models of behavior are only part of the
information we need for successful design
• Need to know how users really are
• Abilities, needs, preferences
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Human Abilities 1
Understanding the user
Typical Person
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Human Capabilities
•
•
Why do we care? (better design!)
Want to improve user performance
Time and effort expended
to complete tasks
•
Knowing the user informs the design
1. Senses
2. Information processing systems
3. Physical responding
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Overview
I. Senses
A. Vision
B. Hearing
C. Touch
D. Smell?
TODAY’S
CLASS
II. Information processing
A. Perceptual
B. Cognitive
1. Memory
a. Short term
b. Medium term
c. Long term
2. Processes
a. Selective attention
b. Learning
c. Problem solving
d. Language
C. Motor system
III. Motor system
NEXT
CLASS
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I. Senses
• Sight, hearing, touch important for current
HCI
– smell, taste ???
• Abilities and limitations
affect design
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Vision
• Visual System
– Eye
– Retina
– Neural pathway
~ 80% of brain’s operation
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• Sensitivity
Visual Abilities
– luminance: 10-6~107 mL (see notes)
• Acuity
– detection, alignment, recognition (visual angle)
– retinal position: fovea has best acuity
• Movement
– tracking, reading, vibrations
• Note: Vision decreases with age
• Implications (??)
– Font size & location depends on task
– Much done by context & grouping
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Color Vision
• Color & the retina
– 380 (blue) ~ 770nm (red)
– Problems with cones or ganglion cells
causes problems with color
perception
– (not really “color blindness”)
– 8% males, 0.5% females
• Implications (??)
– avoid saturated colors
– color coding should be redundant
when possible
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Perception Matters in Usability
• Read-flow principle:
– Action items (buttons, links) should support the flow of the
user in the same way as reading occurs.
– The last action should be the most-likely action to avoid
backtracking.
– Left=back, stop, quit, cancel, previous
– Right=next, continue, submit
<< Previous Slide
Next Slide >>
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Read flow…
FLOWS
DOES NOT FLOW
Hearing
• Capabilities (best-case scenario)
– pitch - frequency (20 - 20,000 Hz)
– loudness - amplitude (30 - 100dB)
– location (5° source & stream separation)
– timbre - type of sound (lots of instruments)
• Implications (??)
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Touch
• Three main sensations handled
by different types of receptors:
– Pressure (normal)
– Intense pressure (heat/pain)
– Temperature (hot/cold)
• Sensitivity, Dexterity,
Flexibility, Speed
• Where important?
– Mouse, Other I/O, VR, surgery
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Overview
I. Senses
A. Vision
B. Hearing
C. Touch
D. Smell?
II. Information processing
A. Perceptual
B. Cognitive
1. Memory
a. Short term
b. Medium term
c. Long term
2. Processes
a. Selective attention
b. Learning
c. Problem solving
d. Language
C. Motor system
III. Motor system
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III. Motor System
• Capabilities
– Range of movement, reach, speed,
strength, dexterity, accuracy
• Often cause of errors
– Wrong button
– Double-click vs. single click
• Principles
– Feedback is important
– Minimize eye movement
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Project (P1)
• Part 1 - Understanding the problem
– Discovery process
– In UCD terms, determine Context/Domain, Users, Tasks,
and their design implications
– Who is it, what do they need to do, and where?
– Interpretive evaluation of current interface, if it exists
– Establish objectives, requirements for (re)design
• Feel free to use Wiki space for sharing, coordination
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Reminder: UCD 9 Steps
1.
2.
3.
4.
5.
6.
7.
8.
9.
Define the Context
Describe the User
Task Analysis
Function Allocation
System Layout / Basic Design
Mockups & Prototypes
Usability Testing
Iterative Test & Redesign
Updates & Maintenance
PROJECT
PART 1
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1. Define the Context
• Context: the “type” of uses, applications
– Life critical systems, applications
– Industrial, commercial, military, scientific,
consumer
– Office, home, entertainment
– Exploratory, creative, cooperative
• Market
• Customer (not the same as the User)
…Design Impacts?…
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2. Describe the User (!!)
• Physical attributes
(age, gender, size, reach, visual angles, etc…)
• Physical work places
(table height, sound levels, lighting, software version…)
• Perceptual abilities
(hearing, vision, heat sensitivity…)
• Cognitive abilities
(memory span, reading level, musical training, math…)
• Personality and social traits
(likes, dislikes, preferences, patience…)
• Cultural and international diversity
(languages, dialog box flow, symbols…)
• Special populations, (dis)abilities
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3. Task Analysis
• Talk to and observe users doing what they do;
find out what they want/need to do
• Explore the PROBLEM SPACE
• List each and every TASK and component
STEPS
 ABSTRACT into standard tasks
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DELIVERABLES
•
•
•
Writeup with your results in HARDCOPY form. Here is how you might structure your project:
Title, team name, team members
Project description
–
•
Context
–
–
–
•
Describe the context in which you expect your application to be used. This isn’t just where it will be used, but also the
implications of that context.
Who would be the customers for your application (may be the same as the users, but may not be)? What impact does
the customer have on the context?
What are the design implications for an application that will be used in this context? Be specific.
Users
–
–
–
•
Give a description of the system you’re working toward and what you expect it will do. This will still be fairly high-level
at this point.
List and define at least three types of stakeholders you’d expect to use your system.
Indicate what characteristics you expect to be relevant to these stakeholders
What are the implications for your design that arise from these characteristics?
Task Analysis
–
–
Describe how you did your task analysis: what methods, what users, how did you do your data collection?
Formal task analysis for your system. Choose the representations you’ll use (e.g., Task Outlines, Narratives,
Hierarchies and Network Diagrams, Flow Charts). Present your task analysis, as well as a justification for the chosen
representations
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Upcoming
•
•
•
•
More on human abilities (cognition)
Task Analysis
Requirements Definition
Evaluation without users
– Heuristic evaluation
– Ethnography
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