Transcript Human Abilities - Personal Web Pages

Human Abilities
Sensory, motor, and cognitive
capabilities
Outline
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Human capabilities
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Senses
Motor systems
Information processing
Memory
Cognitive Processes
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Selective attention, learning, problem
solving, language
Typical Person
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Do we really have limited memory capacity?
Basic Human Capabilities
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Do not change very rapidly
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Not like Moore’s law!
Have limits, which are important to
understand
Our understanding of human capabilities
does change, ie
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Cognitive neuroscience
Theories of color perception
Effect of groups and situation on how we act
and react
Human Capabilities
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Why do we care?
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Better design!
Want to improve user performance
Knowing the user informs the design
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Senses
Information processing systems
Physical responding
Senses (Our Input System)
Sight, hearing, touch important for
current HCI
Smell, taste ???
Abilities and limitations
affect design
Vision Fundamentals
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Retina has
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6.5 M cones (color
vision), mostly at
fovea (1/3)˚
About 150,000 cones
per square millimeter
Fewer blue sensing
cones than red and
green at fovea
100 M rods (night
vision), spread over
retina, none at fovea
Adaptation
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Switching between
dark and light causes
fatigue
Vision implications (more to come in
visual design)
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Color
Distinguishable hues, optical illusions
 About 9 % of males are red-green
colorblind!
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Acuity
Determines smallest size we can see
 Less for blue and yellow than for red
and green
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Color/Intensity
Discrimination
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The 9 hues most people can identify are:
Color
Red
Red-Orange
Yellow-Orange
Green-Yellow
Yellow-Green
Green
Blue-Green
Blue
Violet-Blue
Wavelength
629
596
582
571
538
510
491
481
460
Color Surround Effect
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Our perception of a color is affected by the
surrounding color
Color Surround
Effect of Colored Text on
Colored Background
Black text on white
Gray text on white
Yellow text on white
Light yellow text on white
Green text on white
Light green text on white
Blue text on white
Pale blue text on white
Dark red text on white
Red text on white
Rose text on white
Effect of Colored Text on
Colored Background
Black text on red
Gray text on red
Yellow text on red
Light yellow text on red
Green text on red
Light green text on red
Blue text on red
Pale blue text on red
Dark red text on red
Red text on red
Rose text on red
Effect of Colored Text on
Colored Background
Black text on dark blue
Gray text on dark blue
Yellow text on dark blue
Light yellow text on dark blue
Green text on dark blue
Light green text on dark blue
Blue text on dark blue
Pale blue text on dark blue
Dark red text on dark blue
Red text on dark blue
Rose text on dark blue
Audition (Hearing)
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Capabilities (best-case scenario)
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pitch - frequency (20 - 20,000 Hz)
loudness - amplitude (30 - 100dB)
location (5° source & stream separation)
timbre - type of sound (lots of instruments)
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Often take for granted how good it is
(disk whirring)
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Implications ?
Touch
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Three main sensations handled
by different types of receptors:
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Pressure (normal)
Intense pressure (heat/pain)
Temperature (hot/cold)
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Sensitivity, Dexterity,
Flexibility, Speed
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Where important?
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Mouse, Other I/O, VR, surgery
Smell
Joseph Kaye, “Making scents:
aromatic output for HCI” ACM
Interactions Volume 10, Number 1
(2004), Pages 48-61
Solenoid-controlled scent bottles
Motor System (Our Output
System)
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Capabilities
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Often cause of errors
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Wrong button
Double-click vs. single click
Principles
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Range of movement, reach, speed,
strength, dexterity, accuracy
Workstation design, device design
Feedback is important
Minimize eye movement
See Handbooks for data
Work Station Ergonomics –
to Facilitate I/O
The Mind
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And now on to memory and
cognition…
The “Model Human
Processor”
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A true classic - see Card, Moran and
Newell, The Psychology of HumanComputer Interaction, Erlbaum, 1983
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Microprocessor-human analogue using
results from experimental psychology
Provides a view of the human that fits much
experimental data
But is a partial model
Focus is on a single user interacting with
some entity (computer, environment, tool)
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Neglects effect of other people
Memory
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Perceptual “buffers”
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Short-term (working) memory
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Brief impressions
Conscious thought, calculations
Long-term memory
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Permanent, remember everything that
ever happened to us
LONG-TERM MEMORY
R = Semantic
D = Infinite
S = Infinite
SHORT-TERM (WORKING) MEMORY
VISUAL IMAGE
STORE
R = Visual
D = 200 [70-1000] ms
S = 17 [7-17] letters
AUDITORY IMAGE
STORE
R = Acoustic
D = 1.5 [0.9-3.5] s
S = 5 [4.4-6.2] letters
R= Acoustic or Visual
D (one chunk) = 73 [73-226] s
D (3 chunks) = 7 [5-34] s
S = 7 [5-9] chunks
PERCEPTUAL
PROCESSOR
COGNITIVE
PROCESSOR
MOTOR
PROCESSOR
C = 100 [5-200] ms
C = 70 [27-170] ms
C = 70 [30-100] MS
R = Representation
D = Decay Time
S = Size
C = Cycle Time
Eye movement (Saccade) = 230 [70-700] ms
Perceptual or Sensory
Memory
Very brief, but accurate representation
of what was perceived
 Physically encoded
 Details decay quickly (70 - 1000 ms
visual; 0.9 - 3.5 sec auditory)
 Limited capacity (7 - 17 letters visual;
4 - 6 auditory)
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Sensory Stores
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Iconic – visual
 7 - 17 letters; 70 - 1000 ms decay
Echoic – auditory
 4 - 6 auditory; 0.9 - 3.5 sec auditory
Haptic - touch
Attention filters information into short term memory
and beyond for more processing
Processors – interpret signal into semantically
meaningful
 Pattern recognition, language, etc.
Short Term Memory
Use “chunks”: 7 +- 2 units of
information
 Symbolic, nonphysical acoustic or
visual coding
 Decay 5-226 sec, rehearsal prevents
decay
 Another task prevents rehearsal interference
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About Chunks
A chunk is a meaningful grouping of
information – allows assistance from
LTM
 4793619049 vs. 704 687 8376
 NSAFBICIANASA vs. NSA FBI CIA
NASA
 My chunk may not be your chunk
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User and task dependent
Long-Term Memory
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Seemingly permanent & unlimited
File system full
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Access is harder, slower
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-> Activity helps (we have a cache)
Retrieval depends on network of
associations
How information is perceived, understood
and encoded determines likelihood of
retrieval
LT Memory Structure
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Episodic memory
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Events & experiences in serial form
• Helps us recall what occurred
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Semantic memory
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Structured record of facts, concepts &
skills
• One theory says it’s like a network
• Another uses frames & scripts (like record
structs)
Memory Characteristics
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Things move from STM to LTM by rehearsal
& practice and by use in context
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Do we ever lose memory? Or just lose the
link?
What are effects of lack of use?
We forget things due to decay and
interference
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Similar gets in the way
Recognition over Recall
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We recognize information easier than
we can recall information
Examples?
 Implications?
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Processes
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Four main processes of cognitive
system:
Selective Attention
 Learning
 Problem Solving
 Language
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Selective Attention
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We can focus on one particular thing
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Cocktail party chit-chat
Salient visual cues can facilitate
selective attention
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Examples?
Learning
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Two types:
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Procedural – How to do something
Declarative – Facts about something
Involves
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Understanding concepts & rules
Memorization
Acquiring motor skills
Automotization
• Tennis
• Driving to work
• Even when don’t want to
• Swimming, Bike riding, Typing, Writing
Learning
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Facilitated
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By structure & organization
By similar knowledge, as in consistency in UI
design
By analogy
If presented in incremental units
Repetition
Hindered
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By previous knowledge
• Try moving from Mac to Windows
=> Consider user’s previous knowledge in
your interface design
Observations
Users focus on getting job done, not
learning to effectively use system
 Users apply analogy even when it
doesn’t apply
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Or extend it too far - which is a design
problem
• Dragging floppy disk icon to Mac’s trash
can does NOT erase the disk, it ejects
disk!
Problem Solving
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Storage in LTM, then application
Reasoning
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Deductive - If A, then B
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Inductive - Generalizing from previous
cases to learn about new ones
 Abductive - Reasons from a fact to the
action or state that caused it
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Goal in UI design - facilitate problem solving!
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How??
Observations
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We are more heuristic than
algorithmic
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We try a few quick shots rather than
plan
• Resources simply not available
We often choose suboptimal
strategies for low priority problems
 We learn better strategies with
practice
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Implications
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Allow flexible shortcuts
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Forcing plans will bore user
Have active rather than passive help
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Recognize waste
Language
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Rule-based
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Productive
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We make up sentences
Key-word and positional
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How do you make plurals?
Patterns
Should systems have natural language
interfaces?
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Stay tuned
Recap
I. Senses
A. Sight
B. Sound
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
III. Motor system
A. Hand movement
B. Workstation Layout
People
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Good
1.
2.
3.
xxx
yyy
zzz
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Bad
1.
2.
3.
aaa
bbb
ccc
Fill in the columns what are people good at
and what are people
bad at?
People
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Good
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Infinite capacity LTM
LTM duration &
complexity
High-learning
capability
Powerful attention
mechanism
Powerful pattern
recognition
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Bad
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Limited capacity STM
Limited duration STM
Unreliable access to
LTM
Error-prone
processing
Slow processing
Class Discussion:
Model Human Processor
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What are the three major subsystems and their functions?
What does it mean to say that certain subprocessors have
“variable rates?”
What are some of the other assumptions underlying the
MHP model?
How good is the model?
Scenarios
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Make sure it is a story with
Actors (at least one person)
 Actions (not just the context)
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Good focus on the negative
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Try to follow through with what the
person does