cognitive aspects - university of rochester · 2013-02-05 · cognitive aspects chapter 3 anna...
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Cognitive aspects
Chapter 3
Anna Loparev Intro HCI
University of Rochester
01/31/2013
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What is cognition?
• Set of mental processes relevant to knowledge
• Ex:
Thinking
Remembering
Learning
Daydreaming
Decision Making
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What is cognition?
Seeing
Reading
Writing
Talking
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According to Norman
• Two modes
• Experiential
– Perceive, act, and react to external events
– Requires expertise and engagement
– Ex:
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According to Norman
• Reflective
– Involves thinking, comparing, decision making
– Leads to new ideas and creativity
– Ex:
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For the future…
• Remember these words:
Ball
Critter
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Mental processes
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Attention
• Selecting things to concentrate on
• Allows focus on relevant info
• Involves audio and/or visual senses
• Easy or hard? – Goals
– Info Presentation
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Attention: Goals
• Weak – Hard
– Allow info to guide attention
– Ex: Amazon – MP3 player
• Strong – Easy
– Match goal with available info
– Ex: Amazon – Cowon iAUDIO 9 (16GB)
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Attention: Information presentation
• Digikey vs Adafruit
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Information presentation: Find price of double room at Holiday Inn in Bradley
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Information presentation: Find price for double room Quality Inn in Columbia
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Multitasking and attention
• Effects on memory and attention
– Depends on tasks
– Depends on attention demands
• Ex:
– Gentle music tunes out background noise
– But loud music is distracting
• Light multitaskers better at allocating attention
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Attention: Design implications
• Make important info noticeable
• Make things stand out
– Color
– Ordering
– Spacing
– Underlining
– Animation
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Attention: Design implications
• Avoid cluttering with too much info
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Attention: Design implications
• Avoid using too much just cuz
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Over-use of graphics
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Perception
• How info acquired and transformed into experiences
• Complex; involves
– Memory
– Attention
– Language
• Vision > Hearing > Touch
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Perception: Gestalt laws
• Mind tends to perceive patterns
• Groupings based on certain rules
• Relative strength not really known
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Perception: Gestalt laws
• Core principle:
• Pragnanz
– Regular, simple, orderly
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Perception: Gestalt laws
• Proximity – Close together
• Too much whitespace can be detrimental
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Perception: Gestalt laws
• Similarity
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Perception: Gestalt laws
• Similarity
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Perception: Gestalt laws
• Closure – Incomplete shapes
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Perception: Gestalt laws
• Symmetry
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Perception: Gestalt laws
• Common fate – All moving same way
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Perception: Gestalt laws
• Continuity– Continuous direction
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Perception: Gestalt laws
• Past experience
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Perception: Gestalt laws
• Convexity
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Perception: Gestalt laws
• Common region
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Perception: Gestalt laws
• Element connectedness
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Perception: Is color contrast good?
Find Italian
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Perception: Borders and white space?
Find French
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Perception: Which is easiest to read?
What is the time?
What is the time?
What is the time?
What is the time?
What is the time?
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Perception: Design implications • Icons
– Enable users to distinguish meaning
• Bordering and spacing are effective
• Sounds – Audible and distinguishable
• Speech output – Space out words
• Text – Legible
– Distinguishable from the background
• Tactile feedback – Allow users to recognize and distinguish meanings
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Memory • Includes creating and retrieving memories
• Don’t remember everything
• During creation, affected by:
Attention Context (when, where)
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Memory
• Recall – Remember something without clues
– Can be hard to do • Passwords
• Recognition – Remember via reencounter
– Easier to do than recall
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Recognition versus recall
• Command-based interfaces – Require recall
• GUIs – Provide visually-based options
– Users browse through until they recognize one
• Web browsers, MP3 players, etc. – Support recognition memory
– Provide lists of visited URLs, song titles etc.
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Memory: Search • Start with recall
• Move on to recognition
• Can improve via – Multiple encodings
– Autofill
– Searchbox AND history list
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Memory: Activity
• Do you remember the words?
• Can you identify them in this list? – Basket
– Milk
– Ferret
– Ball
– Soda
– Shirt
– Coffee
– Staple
– Critter
Ball
Critter
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Memory: Activity
• Grandparents’ birthdays
• Cover of last two bought DVDs
• Which easiest? Why?
• Good at remembering visual cues – Color
– Location
– Marks
• Harder to remember arbitrary material – Birthdays
– Phone numbers
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Memory: The classic ‘72’
• George Miller’s (1956)
• How much info people can remember
• Short-term memory capacity is limited
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Memory: What not to do
• Only 7 menu options
• Display only 7 tool bar icons
• No more than 7 bullets in a list
• Only 7 items on pull down menu
• Only 7 tabs at the top of a webpage
• Wrong because recognition, not recall!
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Memory: Design implications
• Don’t require complicated procedures
• Promote recognition rather than recall
• Provide various ways of encoding info – Categories
– Color
– Flagging
– Time stamping
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Learning
• How to learn to use an application
• Use an application to understand a topic
• Hard to learn via manual
– Prefer to learn by doing
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Learning: Design implications
• Encourage exploration
• Constrain and guide learners
• Dynalinking
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Reading, speaking, and listening
• Sentences or phrases mean same thing
• Many prefer listening to reading
• Written is permanent, spoken is transient
• Reading quicker than speaking or listening
• Listening requires less cognitive effort
• Written grammatical, spoken not so much
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RSL: Design implications
• Speech-based interfaces
– Short menus and instructions
– Accentuate intonation of artificial speech
• Allow text to be enlarged
– Zoom
– Actual change in size
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Problem-solving, planning, reasoning and decision-making
• Reflective cognition:
What to do Options
Consequences
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Problem-solving, planning, reasoning and decision-making
• Often involves
– Conscious processes
– Discussion with others (or oneself)
– Use of artifacts
• May involve analyzing different scenarios
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Problem-solving, planning, reasoning and decision-making
• Extent depends on level of expertise
– Novices
• Make assumptions
• Similar situations
• Trial and error
• Slow and error prone
– Experts
• Optimal strategies
• Think ahead
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Problem-solving, planning, reasoning and decision-making
• Overwhelming choice
– Simple heuristics
– Fast decisions that are ‘just good enough’
– Influences product packaging
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PS,P,R,DM: Design implications
• Additional info/functions for those who care
• Support rapid decision-making and planning
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Cognitive Frameworks
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Framework
• Set of interrelated concepts
• Advice in the form of
– Steps
– Challenges
– Principles
– Etc.
• Help constrain and scope
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Mental models
• Includes:
– How to use the system
– How the system works
• Use to infer how to carry out tasks
• Best if matches conceptual model
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Mental models: Examples
• More is more
– The more you turn/push, the greater the effect
Thermostat Oven Elevator
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Mental models: Transparency
• Useful feedback
• Facilitate simple, intuitive interaction
• Clear, easy to follow instructions
• Appropriate help/tutorials
• Context-sensitive guidance
• Two types of users – Those who care about how system works
– Those who don’t
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Gulfs of execution and evaluation
• Gaps between the user and the interface
• Bridge to reduce required cognitive effort
Norman, 1986; Hutchins et al, 1986
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Gulfs of execution and evaluation
• The gulf of execution – Input: Distance from user to system
• The gulf of evaluation – Output: Distance from system to user
Norman, 1986; Hutchins et al, 1986
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Information processing model
• Done to mental representations
– Images
– Mental models
– Rules
– Other forms of knowledge
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Human processor model
• Card et al. (1983)
• Cognition = series of processing stages
• Three types of processes
Perceptual Cognitive Motor
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Human processor model: Pros and Cons
• The Good
– Predicts which processes involved
– Can calculate how long user will take
• The Bad
– Does not account for interactions in real world
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External cognition
• Cognitive processes involved when interact with external representations
• Interaction includes
– Representations
– Tools
• Main goal is to analyze
– Cognitive benefits
– Processes involved
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External cognition: Reduce memory load
• Recall hard – Especially non-visual
• Recognition easy
• Individual notes – Many times with relevant or prominent location
• Note aggregates
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External cognition: Reduce memory load
• Remind need to do something – Buy something for Christmas
• Remind what to do – Buy llamas
• Remind when to do – Order llamas by certain date
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External Cognition: Computational offloading
• Tool + external representation for computation
• Ex:
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External Cognition: Annotation
• Modifying existing representations
• Ex:
– Underlining
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External Cognition: Cognitive tracing
• Manipulate into different orders or structures
• Ex:
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External Cognition: Design implication
• Provide external representations that
– Reduce memory load
– Facilitate computational offloading
• Ex:
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Distributed cognition
• Nature of cognitive phenomena across
Individuals
Artifacts
Internal Representations
External Representations
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Distributed cognition
• Propagation across representational state
• Info transformed through different media
• Ex:
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• Different from other frameworks – More extensive than external cognition
– Focus on system of people and artifacts
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Distributed cognition
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Distributed cognition analysis: What’s involved
• Distributed problem-solving
• Role of verbal and non-verbal behavior
• Coordinating mechanisms that are used – Rules
– Procedures
• Communication
• How knowledge shared and accessed